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Characterisation of Medium Resolution NMR Spectrometers by Instrumental Functions via Reference Deconvolution
Nicolai Zientek1, Franz Dalitz2, Matthias Kraume3, Gisela Guthausen2,
Michael Maiwald1
1 BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489 Berlin, Germany
2 Institute of Mechanical Process Engineering and Mechanics, SRG10-2, KIT, Adenauerring 20 b, 76131 Karlsruhe, Germany
3 Department of Chemical Engineering, Technische Universität Berlin, Straße des 17. Juni 136, MA 5-7, 10623 Berlin, Germany
The development of innovative medium resolution NMR spectrometers (MR NMR) is
remarkable due to their possible applications in quality control, education, or process
monitoring.[1] The use of compact permanent magnets allows to employ NMR devic-
es in an industrial environment without high maintenance requirements and without
the need for cryogenic liquids.[2]
Established tests to evaluate the performance of high resolution (high field) spec-
trometers with cryo-magnets like the line shape test are not sufficient. The reason for
this is the deviation from the Lorentz-Gaussian line shape due to the imperfect mag-
netic field and other distortions. Moreover, high resolution performance tests using
expensive deuterated solvents or standards and are difficult to handle in open sys-
tems.
Our approach is to deconvolute the spectrum of an appropriate sample with an ideal
line shape in order to obtain the instrumental function in the time domain. The instru-
mental function provides maximum possible information about the line shape distor-
tion and is therefore particularly suitable as a characterization method. In addition,
readily available fluids like acetone, water, etc. can be used for these tests. In this
study, common line shape distortions, e.g., field drifting, asymmetric line shapes, or
line broadening was simulated and deconvolution with the ideal line shape was used
to receive the corresponding instrumental functions. Herein, the disturbing signal
components of the FID (free induction decay, original NMR signal) could be retrieved
and demonstrate the potential of this approach.
[1] F. Dalitz, M. Cudaj, M. Maiwald, G. Guthausen, Process and Reaction Moni-
toring by low-field NMR spectroscopy, Prog. Nucl. Magn. Reson. Spectrosc.
60 (2012), 52–70.
[2] J. Mitchell, L.F. Gladden, T. Chandrasekera, E. Fordham, Low-Field Perma-
nent Magnets for Industrial Process and Quality Control, Prog. Nucl. Magn.
Reson. Spectrosc. (in press).
Observation Stops Motion: �e Quantum Zeno E�ect
Max Strauß ∗, Janik Wolters, Simon Schönfeld, Oliver BensonAG Nano-Optik,Humboldt-Universität zu Berlin, Germany
�e quantum Zeno e�ect is one of the most intriguing phenomena predicted by quantumme-chanics. It describes the inhibition of coherent evolution by measurements. We demonstrate thisphenomenon using single nitrogen vacancy centres in diamond.
Nitrogen vacancy (NV) centres in diamond exhibit some remarkable properties singling themout among the many solid state quantum systems. �e NV centre is a stable emitter of singlephotons and boasts spin coherence times on the order of milliseconds even at room temperature.As a consequence, their optical and magnetic properties have been in the focus of very intense andactive research in recent years [1].
Figure 1: Illustration of the experiment. Initially, the electron spin of a single NV centre is pre-pared in the state “up”. Now, application of a microwave π-pulse �ips the spin “down”. Undernormal circumstances, a subsequent measurement would yield the result “down” with unity prob-ability. However, if the spin state is measured during the microwave pulse, a second measurementperformed a�erwards shows an increased probability that the spin did not �ip. From [2].
Using optically detected magnetic resonance (ODMR), we are able to coherently manipulatethe electronic spin of single NV centres. Our experiments show that by optically measuring thespin state during a microwave induced coherent transition, the coherence between spin states canbe destroyed. �ereby, further evolution is suppressed (see �gure 1) [3]. Furthermore, our stud-ies allow to thoroughly characterise the NV centre with respect to coherent as well as incoherentprocesses. �ese insights will prove useful in future experiments where the NV centre is used as ascanning quantum emitter probe for lifetime or decoherence microscopy [4].
References
[1] Oliver Benson. “Assembly of hybrid photonic architectures fromnanophotonic constituents.”In: Nature 480.7376 (Dec. 2011), pp. 193–9.
[2] “Durch Beobachten bewegen”. In: Humboldt 58.1 (Oct. 2013), p. 5.
[3] Janik Wolters et al. “Quantum Zeno phenomenon on a single solid-state spin”. In: PhysicalReview A 88.2 (Aug. 2013), p. 020101.
[4] AW Schell, P Engel, and O Benson. “Probing the local density of states in three dimensionswith a scanning single quantum emitter”. In: arXiv:1303.0814 (2013).
EMIL The Energy Materials In-situ Laboratory: Tools for Energy Research
Starr, D. E.1; Reichardt, G.
1; Bär, M.
1, 2; Lauermann, I.
1; Schulze, T.
1; Bahrdt, J.
1; Hendel, S.
1;
Schäfers, F.1; Hävecker, M.
1, 3; Knop-Gericke, A.
3; Lips K.
1
1Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
2Institute for Physics and Chemistry, Brandenburgische Technische Universität Cottbus, Cottbus,
Germany
3Fritz-Haber Institute of the Max Planck Society, Berlin, Germany
In a joint effort, the Helmholtz-Zentrum Berlin (HZB) and the Fritz-Haber-Institute of the Max-Planck-
Society will construct EMIL, the Energy Materials In-situ Laboratory, at the HZB’s BESSY II synchrotron
radiation facility. EMIL will combine innovative and industrially relevant thin-film deposition clusters
with synchrotron-based X-ray analysis to study photovoltaic and (photo-)catalytic materials. The
ultimate goal of EMIL is to provide a scientific foundation for the development of next-generation
solar energy conversion devices.
EMIL will have two end-stations, one focusing on investigating catalytic materials (CAT) and the other
on photovoltaic materials (SISSY). These end-stations will receive light from two undulators in the
BESSY II storage ring covering an energy range of approximately 80 eV to 10 keV. The CAT end-station
will focus on near ambient pressure hard X-ray photoelectron spectroscopy (NAP-HAXPES) while the
SISSY end-station will provide a range of X-ray analysis techniques to study the chemical and
electronic structure of materials at a variety of depths at ultra-high vacuum conditions. These
techniques will include X-ray emission and absorption spectroscopies (XES and XAS), X-ray
fluorescence (XRF), as well as soft and hard X-ray photoelectron spectroscopy (XPS and HAXPES). This
poster will provide an overview of the analytic capabilities of the EMIL facility, their connection to
thin-film deposition facilities and an overview of the scientific themes to be investigated at EMIL.
A Ruler for the Nanoworld: EUV and GISAXS Scatterometry
Victor Soltwisch, Jan Wernecke, Anton Haase, Christian Laubis,
Michael Krumrey and Frank Scholze
Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin
The continuous shrinking in feature size of integrated circuits in the semiconductor industry is a huge technical challenge. The predicted technical switchover to EUV photo-lithography with wavelengths at 13.5 nm will replace the 192 nm lithography systems. Beside the well-known technical issues, there exist also a absolute failure in critical dimen-sion (CD) metrology. Most actual development focus on in-situ mask defects detection and repair, which is a critical issue for the high-volume manufacturing. In- and ex-situ metro-logy solutions are needed which are fast enough, non-destructive and have capabilities for 3D structures. EUV scatterometry (see Fig. 1), a part of the optical scatterometry (OCD) solutions, could complete the existing metrology tools.
Angle resolved scatterometry is based on the analysis of light scattered from a periodic structure (e.g. grating). For complex structures the inverse problem could not be solved analytically. However, for this purpose finite-element Maxwell solver are used often (FEM). They allow exact geometric modeling (by using unstructured meshes) and high accuracy at low computational cost. In the EUV scatterometry with an incident angle close to normal, the constructed model shows a good agreement with other direct measurement methods like CD-AFM.EUV scatterometry is also very sensitive for imperfections of the multilayer. Accurate know-ledge of the multilayer is important for the recon-struction of diffracted intensities from a grating structure which lies on top of the multilayer. To increase the sensitivity we extend this scattero-metric approach to grazing incidence small angle X-ray scattering geometry (GISAXS) and study the influence of the multilayer (see Fig 2). We show first results of preliminary GISAXS and FEM studies of the reconstruction of a silicon grating with a nominal critical dimension of 50 nm which was fabricated with electron beam lithography.
contact: [email protected] Adlershofer Forschungsforum | 12.11.2013
Fig. 1. Sketch of near normal incidence scattering from EUV photomask. Geometric dimension of the grating e.g. line widths, line height or sidewall angles, can be derived from the scattering pattern (blue).
Fig. 2. Simulation of the specular reflectance from EUV multilayer mirror in grazing incidence scattering geometry.
Agnieszka Siwek
Humboldt-Universität zu Berlin
Institut für Chemie
Brook-Taylor-Straße 2
12489 Berlin
Mail: [email protected]
Phone: 030 20937233
Activation of Halogenated Methanes by Lewis-Acidic Aluminum Fluoride Surfaces
The environment is highly polluted by the release of chlorofluoro ar ons CFC’s which are
environmentally relevant due to their "super greenhouse gas" behavior. These halogenated
compounds are ubiquitous and persistent because of their C-X bonds (X= Cl, F) which are difficult to
cleave. Hence, the activation and depletion of such compounds under moderate reaction conditions
is of major industrial and academic interest. Moreover the conversion of C-X bonds would open up
new reaction pathways for chemical synthesis. Recently, a new approach was developed for the
cleavage of C-X bonds which involves an electrophilic activation. The C-X bonds activation occurs on
the surface of strong Lewis-acidic nanoscopic aluminum fluorides in the presence of Et3SiH. The
strong Lewis-acidic sites on the surface can generate silylium-like species from Et3SiH which promote
the cleavage reaction of the C-X bonds. The C-X bonds can be converted catalytically into C-H or
C-C bonds via hydrodehalogenation or Friedel-Crafts type reactions, respectively. A first insight on
the aluminum fluoride surfaces and crucial reaction steps of the mechanism was obtained by 1H- and
19F-MAS NMR spectroscopy, TA (thermal analysis) as well as by PulseTA® experiments.
In-situ Studies of the Lithium Incorporation into Lithium-Ion Batteries ModelSystemsBeatrix-Kamelia Seidlhofer, Bujar Jerliu, Erwin Hüger, Roland Steitz, Harald Schmidt
Abstract In the field of automotive transportation lithium-ion batteries with highcharge/discharge rates and high power densities are required. The latter factors are dependenton the diffusion and/or interface controlled insertion of Li into solid hosts. To this end it isnecessary to understand the kinetic processes going on at the electrodes to optimize chargingtimes and to increase power density. We conducted neutron reflectometry studies on theintercalation of Li into amorphous silicon during galvanostatic charging/discharging at roomtemperature. By the concurrent changes in reflectivity of the electrode/electrolyte interface wewere able to monitor the formation and movement of the LixSi phase in the working electrodein-situ. The obtained results give important information on the lithiation mechanism, which isthe first step in enhancing the properties of Lithium-ion batteries.
Contact DataDr. Beatrix-Kamelia SeidlhoferF-ISFM Soft Matter and Functional MaterialsHelmholtz-Zentrum Berlin für Materialien und Energie GmbHHahn-Meitner-Platz 1D-14109 Berlin
Office: 030 / 8062 43069Fax: 030 / 8062 - 43094Email: [email protected]
LASER BASED SEPARATION OF SHUNTS WITHIN SILICON AND CHALCOPYRITE BASED SOLAR
CELLS
C. Schultz1, S. Kühnapfel2, R. Mayerhofer3, M. Schüle1, K. Stelmaszczyk1, M.Weizman1, F. Friedrich4
B. Rau5, R. Schlatmann1,5, V. Quaschning1, B. Stegemann1 , F. Fink1
1 HTW Berlin - University of Applied Sciences, Wilhelminenhofstr. 75a, 12459 Berlin, Germany
2 Helmholtz-Zentrum für Materialien und Energie, Institut für Silizium-Photovoltaik, 12489 Berlin, Germany
3 ROFIN-BAASEL Lasertech GmbH & Co. K, Petersbrunner Str. 1b, 82319 Starnberg, Germany
4 Technical University Berlin, FG HLB /PVcomB, Einsteinufer 19, 10587 Berlin, Germany 5 PVcomB - Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Schwarzschildstr. 3, D-12489 Berlin,
Germany
ABSTRACT: In industrial thin film solar cell production point-like defects can occur due to material impurities or by
”rough” substrate handling between the different processing steps. Such defects can cause disproportionate power
losses or even local shortcuts in the solar cells. The removal of these defects would increase the solar cell
performance as well as the overall manufacturing yield. In our study we present a technique for identification of
shunted regions by means of lock-in thermography and subsequent successful laser based removal of shunts in silicon
and chalcopyrite (CIGSe) solar cells. These results show that the removal of point-like defects increases the overall
device performance significantly.
Keywords: Laser Processing, Shunts, Thin Films, Silicon, Cu(In,Ga)Se2
Laser patterning of CIGSe solar cells using nano- and picosecond
pulses - possibilities and challenges
Manuel Schülea*, Christof Schultza, Valdemaras Juzumasb, Kamil Stelmaszczyka, Moshe
Weizmana, Björn Raub, Rutger Schlatmanna,b, Volker Quaschninga, Bert Stegemanna, Frank Finka
a HTW Berlin - University of Applied Sciences, Wilhelminenhofstr. 75a, D-12459 Berlin, Germany
b PVcomB / Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Schwarzschildstr. 3, D-12489 Berlin,
Germany
*Corresponding author:
[email protected], Phone: +49 30 8062 18156, Fax: +49 30 8062 15677
In solar cell manufacturing it is essential to interconnect single solar cells into one solar module in
order to gain a high voltage output with a relative low current in order to minimize the losses. In thin
film solar cell technology this interconnection can be achieved by alternating layer deposition and
removal of very small lines in order to isolate or connect adjacent cells.
In this study different approaches of successful laser scribing/material ablation of CIGSe thin film
solar cells were examined concentrating on the second and third patterning step. These two
patterning steps consist of the ablation of the absorber layer (P2) for creating a direct connection
between front and back contact. The ablation of the front contact (P3) is for isolating adjacent cells.
Different to Silicon thin film module manufacturing, in CIGSe technology it is still common to use
mechanical tips for carrying out the above mentioned scribing steps. Nevertheless, this mechanical
scratching has some disadvantages, e.g. cracking and chipping of the absorber and TCO layer,
maintenance and hence machine downtime for replacing and adjusting the tips. By using a laser for
the patterning these undesired affects can be minimized. However, other negative effects may occur,
for example, shunting of the absorber layer due to the heat input of the laser beam which is still the
most challenging problem when using laser sources for patterning CIGSe thin film solar cells [1].
In this paper we show that it is possible to carry out the patterning of CIGS solar cells with a laser and
achieve high efficiency solar modules. This is demonstrated for different kinds of samples as well as
varying laser types. The lasers differ in the wavelength of their radiation (532 and 1064 nm) and also
in the pulse widths which are at pico- or nanosecond timescale. Consequently, using different kinds
of laser types requires different ablation approaches. Short laser pulses, for instance, are
advantageous if an ablation of specific layers is intended. Longer pulse durations are beneficial when
melting and recrystallization of the absorber layer is desired [2]. Therefore, a thorough study and
understanding of the correlation between laser parameters and ablation behavior is essential. The
results obtained were analyzed and evaluated via optical and scanning electron microscopy, energy
dispersive X-ray spectroscopy and electrical measurements such as determination of contact
resistances and I-V-curves. With this knowledge we were able to set up a suitable laser based scribing
process for CIGS thin film solar cells.
[1] G. Eberhardt, H. Banse, U. Wagner, T. Peschelb. In: SPIE Proceedings Vol. 7585 (2010)
[2] C. Schultz, M. Schüle, M. Richter, H.-U. Pahl, H. Endert, J. Bonse, I. Dirnstorfer, B. Rau, R. Schlatmann, V.
Quaschning, F. Fink, B. Stegemann. In: Proc. 26th EU-PVSEC (2011) p. 2540
Synthesis and Characterization of nano-SrF2 and -YbF3 for Dental
Applications
Larisa Schmidt, Erhard Kemnitz*
Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor-Str. 2, 12489 Berlin, Germany
Nanoscopic metal fluorides are nowadays of great interest in different application fields like optics,
catalysis, material science and medicine. Due to its optical properties e.g. its low refractive index
(nD= 1.439 @ 589 nm), the high transmission in the IR and UV spectral range (0.13-11 µm) and
the low solubility in water (120 mg.L-1) SrF2 is an ideal material for optical applications and is often
used as a coating material for high-quality optical windows and lenses. Furthermore, SrF2 and YbF3
are used in medicine for maintaining healthy bones and teeth.[1] They are of significant interest in
dentistry as inorganic fillers in dental composites and therefore can improve the mechanical and
chemical properties of dental materials.[2] Moreover, by introducing SrF2 and YbF3 nanoparticles
into dentinal tubules and caries infected areas, respectively, they may act as a fluoride reservoir
providing a long-term fluoride release that is ascribed to their low solubility. This potential to
increase the fluoride level in dental hard tissues is of great interest in caries prevention.
Figure 1. Fluorolytic sol-gel synthesis of metal fluoride nanoparticles.
Nanoscopic metal fluorides MFn (M = Sr, Yb) have been successfully synthesized via the fluorolytic
sol-gel synthesis.[3] The reaction of the metal precursors with alcoholic HF solution in organic
solvents yields in transparent, low viscous metal fluoride sols. The investigation by dynamic light
scattering (DLS), X-Ray powder diffraction (XRD), transmission electron microscopy (TEM) and N2
adsorption/desorption measurements (BET) confirmed the existence of sol particles in lower
nanometer ranges. Utilizing spectroscopical and crystallographic methods (solid state NMR, XRD
and WAXS) allowed us to gain more chemical and structural information during the aging process
as well as the long-time behavior of the sols.[4]
Furthermore, the fluorolytic sol-gel synthesis has been modified for the preparation of transparent
inorganic-organic nanocomposites with a high amount of inorganic nanoparticles (13 wt% SrF2 and
40 wt% YbF3) in a polymer matrix commonly used in dental materials.
[1] D. S. Bauer, N. Karpukhina, G. Kedia, A. Bhat, R. V. Law, I. Radecka, R. G. Hill, J. R. Soc. Interface, 2012,
1742-5662.
[2] L. Ling, X. Xu, G. Choi, D. Billodeaux, G. Guo, R.M. Diwan, J Dent Res, 2009, 88(1), 83-88.
[3] E. Kemnitz, U.Groß, S. Rüdiger, C.S. Shekar, Angew. Chem. Int. Ed. 2003, 42, 4251.
[4] L. Schmidt, F. Emmerling, H. Kirmse, E. Kemnitz, RSC Adv., DOI:10.1039/C3RA43769H.
From Synchrotron to the Laboratory – X-ray Absorption Spectroscopy for the Determination of Chemical States
L. Anklamm1, T. Bidu
1, W. Malzer
1, C. Schlesiger*
1, S. Schuh
1, J. Stark
1 and B. Kanngießer
1
1Institute for Optics and Atomic Physics, Technical University Berlin, Hardenbergstr. 36, 10623
Berlin, Germany
Analytical Sciences are at the core of many of today’s fundamental and applied scientific problems. Analytical Sciences are also indispensable in high technology production. Analytics is a cross-sectional science and the School of Analytical Sciences Adlershof, SALSA is a response to the increasing demand for it. Against this background, we present one of our developments, which transfers a well-established Synchrotron method, X-ray Absorption Near Edge Structure Spectroscopy (XANES), to the laboratory.
XANES is a method which is suitable for obtaining information about the chemical state of various types of samples. This includes the elemental analysis as well as the oxidation state and bond lengths. A high spectral resolving power in combination with a brilliant source is required for these kinds of experiments.
We nevertheless were able to develop a highly efficient wavelength-dispersive spectrometer based on a newly developed graphite mosaic crystal. The special spectrometer geometry and the crystal used allow us to perform XANES measurements in the laboratory with acquisition times of about 30 min. The spectral resolving power we achieve is ca. E/ΔE ≈ 2000. With this spectrometer we can handle solid state samples like powders as as fluids. The sample thickness ranges from microns to millimeter depending on the investigated element and the matrix.
In this contribution we will present our setup including an example for determining the oxidation state and the mixture by means of the ratio of area densities for Fe/Fe2O3. Additionally the capability to obtain the bonding lengths for a liquid sample containing Nickel is shown.
* [email protected], TU Berlin, Sekr. EW 3-1, Hardenbergstr. 36, 10623 Berlin
Fig. 1: Comparison of XANES spectra measured at the
synchrotron as well as in the laboratory at the Nickel K-
edge.
Development of a HPLC-MS-Method for the Quantification of Enniatin B in Fermented Feed
S. Schloß, Berlin/D, S. Kutscha, Berlin/D, M. Koch, Berlin/D, M. Proske, Berlin/D, R. Maul, R., Berlin/D
Svenja Schloß, Federal Institute for Material Research and Testing (BAM), Richard-Willstätter-Str. 11, 12489 Berlin/D
Within the chemical class of cyclic depsipeptides, the enniatins (ENN) are becoming increasingly significant. As secondary metabolites of various Fusarium species, they represent a common food and feed contamination mainly affecting cereal products
[1]. Due to the antimicrobial and cytotoxic effects of ENN, an increased intake of ENN-contaminated feed might have an impact on the microbiota in the rumen of farm animals. Microbial metabolism may lead to a degradation or conjugation of ENN resulting in modified physiological effects. In contrast, any alteration or reduction in metabolic activity of ruminal microorganisms due to the presence of ENN might exert a (negative) influence on the performance of farm animals.
The purpose of the present investigation was to develop a sensitive method suitable for the quantification of ENN B in fermented feed samples. Due to the complexity of these matrices, the detection of ENN B at trace levels (µg kg-1) is a challenge.
The investigated feed sample consists of wheat pellets and hay; therefore, it has a high content of proteins and polysaccharides like starch and cellulose. During the ruminal fermentation process, the substrate is processed by microorganisms, resulting in a formation of soluble substances – e.g. glucose, fatty acids, and peptides.
Mass spectrometry was found to be a suitable method for the quantitative determination of ENN B in complex fermented feed samples. However, coelution of matrix components may lead to ion suppression or ion enhancement effects in HPLC-MS-analysis, which requires the use of isotope-labeled internal standards.
In order to ensure that the moist and fibrous sample material is completely chopped and blended, a freeze-drying step was included. Subsequently the samples were ground to a fine powder with a laboratory mixer. Aliquots of the sample were spiked with a 15N-labeled internal standard
[2], reconstituted to a water content of 80 % to support soaking, and extracted with acetonitrile. For purification of sample extracts, an approach modified from the QuEChERS method was applied. The purified extracts were analyzed by using HPLC-ESI-(+)-MS/MS. For MS-based quantification the precursor−product ion transitions monitored at SRM mode were m/z 640,3 → 196,0 m/z for native ENN B and m/z 643,4 → 197,0 for 15N-labeled ENN B.
The limits of detection and quantification were determined to be 13 µg kg-1 and 49 µg kg-1 ENN B respectively. Therefore, the developed method is applicable for the determination of ENN B in complex fermented feed samples and results of our investigation will be outlined and discussed.
[1] A. Malachova et al., Journal of Agricultural and Food Chemistry 2011, 59 (24), 12990-7. [2] L. Hu et al., Journal of Agricultural and Food Chemistry 2012, 60 (29), 7129-36.
Structure-property relationships in thin-film solar cells by scanning electron microscopy Norbert Schäfer
1, Daniel Abou-Ras
1, A.J. Wilkinson
2, Melanie Nichterwitz
1, Holger Kropf
1, T. Rissom
1
1. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany 2. Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
[email protected] Keywords: EBSD, FIB, EBIC, strain measurements
Chalcopyrite-type solar cells based on Cu(In,Ga)Se2 absorber layers have shown power-
conversion efficiencies of more than 20 % on glass and polyimide substrates [1,2,3]. The analysis of the microstructure of the Cu(In,Ga)Se2 absorber layer and of the corresponding structure-property relationships is essential for further improvement of the photovoltaic performance.
Scanning electron microscopy (SEM) offers several techniques for investigating the microstructure of the Cu(In,Ga)Se2 absorber layers. Focused ion beam (FIB) was used to prepare the cross-sectional specimens for SEM imaging and analysis by slicing and polishing of the ZnO/CdS/Cu(In,Ga)Se2/Mo/glass solar-cell stacks without delamination of the individual layers. This allowed us to perform electron backscatter diffraction (EBSD), electron-beam-induced current (EBIC) and energy-dispersive X-ray spectroscopy measurements on identical positions of the specimens, in order to correlate microstructural and electrical properties as well as elemental distributions to the performances of the solar cells.
The investigated Cu(In,Ga)Se2 layers showed average grain sizes of 0.5-1.5 µm, depending on their compositions [4] (see figure 1a for an example). EBSD also allowed the first evaluation of microstrain variations within individual grains in CuInSe2 layers using CrossCourt3 analysis software (see Fig. 1b for an example). Small shifts of features within the measured EBSD patterns can be related to variations in microstrain, which were found to be of the order of 10
-3.
1. P. Jackson et al, Prog. Photovolt.: Res. Appl. 19 (2011), p. 894. 2. See press release at http://www.empa.ch/plugin/template/empa/*/131441 3. http://www.zsw-bw.de/uploads/media/pi18-2013-ZSW-WorldrecordCIGS.pdf 4. D. Abou-Ras, S.Schorr and H.W. Schock, J. Appl. Cryst. 40 (2007), p. 841. 5. Special thanks are due to B. Bunn, C. Kelch, M. Kirsch, T. Münchenberg, and J. Schniebs for solar-cell processing. Financial support by the Helmholtz Virtual Institute Microstructure Control in Thin-Film Solar Cells, VI-520, is gratefully acknowledged.
Figure 1: (a) EBSD orientation map of CuInSe2 layer. (b) Strain distribution inside individual grain.
(a)
(b)
substrate side
capping layers
Preparation of core-shell particles for FRET-based detection in suspension arrays using
flow cytometry
Dominik Sarma, Knut Rurack
Fachbereich 1.9 Sensormaterialien
BAM Bundesanstalt für Materialforschung und -prüfung
http://www.bam.de/div-19.htm
Suspension arrays play a major role in recent developments of multiplexed proteomic and
genomic assays. Using cytometry, this microparticle-based analytical method features several
advantages compared with flat array technologies such as facile fabrication of the analytical
platform, high analytical surface area, fast reaction kinetics and a high analytical throughput.1
Since the first immunoassay for soluble antigens employing flow cytometry was developed in
1982 by Lisi et al.,2 enormous improvements were made concerning the assay chemistry and
multiplexing capabilities of this technique.3
However, major drawbacks for reliable quantitative measurements with such assays are a
strong dependence of the fluorescence intensity signal on environmental changes and the
demand for improved analytical standards and reference materials of high purity, which are not
straightforward to prepare and in many cases very costly. The latter limit the accessibility and
economic benefit of the method. A way to circumvent these drawbacks is ratiometric signaling
that comprises a built-in correction for environmental effects.4 Moreover, measuring the ratio
of fluorescence intensities at two wavelengths (or detectors in flow cytometry) provides a self-
referenced signal, which renders single particle analytics intrinsically more reliable.
Figure 1: Left – Core-shell particles with donor dye-containing shell and DNA-labeled model probe; right – spectral
overlap (J) of donor and acceptor dye.
This contribution presents micron-sized core-shell particles with a donor dye-containing shell
and an acceptor dye-labeled DNA model probe (Figure 1). Förster resonance energy transfer-
(FRET) type interactions between the two dyes is characterized with steady-state fluorescence
in a conventional spectrometer and with flow cytometry at the single-particle level.
This proof-of-concept illustrates the possibility of ratiometric signaling in particle-based
suspension arrays with flow cytometry.
Literature:
[1] J. P. Nolan, L. A. Sklar, Trends Biotechnol. 2002, 20, 19.
[2] P. J. Lisi et al., Clin. Chim. Acta 1982, 120, 171.
[3] M. Han et al., Nat. Biotechnol. 2001, 19, 631.
[4] W. de Jager et al., Clin. Vaccina Immunol. 2003, 10, 133.
Fabrication and Characterisation of disk-shaped Microresonators
Christoph Pyrlik1*
, Daniel Bremer1
, Oliver Neitzke2
, Oliver Benson2
, Andreas Thies1
, and Andreas Wicht1
1. Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany
2. Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin, Germany
* [email protected], Tel: 030 6392-2763
Optical resonators with high photon storage times and corresponding narrow linewidth have
widespread applications in a diverse field from scientific research to industrial applications.
Recently, optical microresonators with diameter smaller than 1 mm have garnered attention.
The common trait of those devices is a radial geometry (spheres, discs, toroids etc) which
results in whispering-gallery modes along the perimeter of the structure. The unique feature
of those modes is the combination of an ultra-high quality-factor with high optical power
densities due to a very small mode volume. At the FBH, we are developing a technology
platform based on disk-shaped SiO2 microresonators to enable this technology for micro-
optical integration in complex optical systems.
Figure 1: REM cross-section of an optical microdisc (left); space-resolved coupling
to microresonators (right).
We report on the development of a fabrication process for SiO2-based optical
microresonators and the optical characterisation of the realised structures. Disk-shaped
resonators with varying oxid thickness and diameters have been processed. We present the
experimental setup that is used for the optical characterization and the automated
measurement schemes that have been implemented.
We achieved a maximum quality-factor of 6.7*1E6 for a disk resonator with a diameter of 300
µm at a resonance wavelength of 780nm. The resulting free spectral ranges vary from 0.2 to
1.3 THz and match well with the theoretical model. Furthermore we present research on the
space-resolved coupling to optical microresonators. This measurement show the areas in
which the coupling between the coupling device and the microresonator are optimal.
Acknowledgements. This work is supported by the Europian Union with funds provided by the Investitionsbank
Berlin under grant number 10147034.
The Joint Lab for Structural Research (JLSR) - Combining Electron Microscopy, Scanning
Force Microscopy and more for Advanced Nanostructural Analysis
F. Polzer,1 N. Severin,
1 F. Chu,
2 M. Ballauff,
2 J. P. Rabe
1
1 Department of Physics, Humboldt-Universität zu Berlin, Newtonstr.15, 12489 Berlin
2 Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien and
Energie, Hahn-Meitner-Platz 1, 14109 Berlin
Abstract
Complex colloids have become important model system for studying the fundamental principles of
crystallization processes as well as for advanced applications in drug delivery, modern diagnostics and
many others. These particulate systems often possess a very well-defined, complex structure on the
nano-scale that affords state-of-the-art characterization techniques to reveal their real nature. The Joint
Lab for Structural Research Berlin (JLSR) that has been established in 2011 by the Humboldt-
Universität zu Berlin, the Helmholtz-Zentrum Berlin and the Technische Universität Berlin offers a
broad variety of characterization methods ranging from electron microscopy and force microscopy to
X-Ray experiments and more to cover the needs of complementary characterization as requested in
numerous scientific fields.
We herein demonstrate how a combination of transmission electron microscopy (TEM), cryogenic
TEM and different methods of scanning force microscopy (SFM) can be used to fully characterize the
morphology of well-defined hollow, thermoresponsive colloids.
Figure 1. Schematic representation of the synthesis and structure of thermosensitive, hollow PNIPAM
particles in cross-sectional view of the particles (upper panel). CryoTEM micrograph (lower left) and
SFM (lower right) height and phase images showing their structure in solution and on solid substrate.
These colloids have a poly(N-isopropyl acrylamide) (PNIPAM) shell that shows a lower critical
solution temperature (LCST) in water. The structure of such hollow microgels in solution as well as
their LCST behavior can be elucidated by cryogenic TEM. In addition, SFM is capable to provide high
resolution images of the capsules’ topography as well as a quantitative mapping of their nano-
mechanical characteristics. Furthermore, SFM imaging allows gaining insight onto interactions
governing self-assembly of the capsules on solid substrates. Therefore, we demonstrate that a
combination of both microscopy techniques is able visualize the complex morphology including
thermo-responsive properties in solution and interactions on solid substrates of these capsules.
Fluorescence Polarization Immunoassays for Caffeine
L. Oberleitner1,2, J. Grandke1,2, F. Mallwitz3, L.-A. Garbe2, R. J. Schneider1
1 BAM Federal Institute for Materials Research and Testing, Berlin, Germany 2 Technische Universität Berlin, Berlin, Germany
3 aokin AG, Berlin, Germany
Caffeine is one of the most frequently consumed behaviorally active substances in the world [1]. It is present in coffee, tea, cocoa, soft drinks, and energy drinks; there are even beers and cosmetics containing caffeine. Besides the instrumental meth-ods, e.g. LC-MS/MS, there are enzyme immunoassays for the quantification of caf-feine in beverages [2]. These methods are characterized by a very high sensitivity, a wide quantification range, and a good applicability to many different sample matrices [3]. Another advantage of immunoassays over instrumental methods is that sample preparation is not necessary. The fluorescence polarization immunoassay (FPIA) is a homogeneous assay, which offers the same advantages as the other immunoassays [4]. In contrast to the above mentioned assays, the FPIA does not require any washing steps. Additionally, only one incubation step of a few minutes is required. Kinetic FPIAs do not need any in-cubation step. Therefore, this assay is significantly faster and easier automatable than enzyme immunoassays. We developed a FPIA for caffeine determination and compared the performance of this assay on microtiter plates (MTPs) and in cuvettes. With the assay in cuvettes the kinetics of the degree of polarization can be measured and therefore no incubation step is required. The FPIA on MTPs requires an incubation time of 10 min. Calibra-tion curves were determined and the quantification ranges of the formats were calcu-lated based on precision profiles. Both caffeine FPIAs showed test midpoints in the lower microgram per liter range. These values can be seen as a parameter for sensi-tivity. Comparing these values with those obtained for the caffeine ELISA (test mid-point 95 ng/L) [3], the FPIAs show lower sensitivities. Due to the high caffeine con-centrations in beverages, this is not necessarily a disadvantage for this application. The FPIA in cuvettes showed a broader quantification range, while the MTP-based assay led to a slightly lower quantification limit. Both FPIAs were used to determine the caffeine concentrations of several beverag-es. The results obtained on MTPs showed coefficients of variation (CVs) of up to 50%. Therefore, this format is not suitable for the caffeine determination in real sam-ples. The FPIA performance in cuvettes showed very low CVs for all tested matrices, including decaffeinated coffee. The FPIA performed in cuvettes is a fast, semi-automatic tool for the caffeine quantification with a widespread applicability. Literature: 1. Fredholm, B. B.; Battig, K.; Holmen, J.; Nehlig, A.; Zvartau, E. E., Pharmacol. Rev. 1999, 51, 83-133. 2. Carvalho, J. J.; Weller, M. G.; Panne, U.; Schneider, R. J., Anal. Bioanal. Chem. 2010, 396, 2617-2628. 3. Grandke, J.; Oberleitner, L.; Resch-Genger, U.; Garbe, L.-A.; Schneider, R. J., Anal. Bioanal. Chem. 2013, 405, 1601-1611. 4. Gutierrez, M. C.; Gomez-Hens, A.; Perez-Bendito, D., Talanta 1989, 36, 1187-1201.
Contact: [email protected]; phone: +49 30 8104-5528
SPRITE Work Package 3
Extending Analysis – High Resolution PIXE
S. H. NowakIfG - Institute for Scientific Instruments GmbH, 12489 Berlin, Germany
J. BuchrieglerHelmholtz-Zentrum Dresden–Rossendorf e.V., 01328 Dresden, Germany
SPRITE is a multi-disciplinary European training network which brings together Europeʼs premier research institutes in technology and applications of ion beams. SPRITE addresses the urgent European need - to train the next generation of researchers in this multi- and supra- disciplinary emerging field. "Extending Analysis – High Resolution PIXE" – the 3rd work package of SPRITE – aims to develop a new high-speed PIXE tool for spatially resolved PIXE analysis, employing a broad proton beam and a parallel beam wavelength-dispersive spectrometer for micro PIXE analysis (SLcam®). The project work is directed to qualify such systems for routine PIXE measurement. A second strand to this project is to develop a digital pulse processor to improve the resolution of gas detectors. SPRITE is a part of EUʼs Marie Curie Initial Training Networks action with a project no 317169.
In situ characterization of crystallization processes
Yen Nguyen Thi1, Tanja Gnutzmann
1, Klaus Rademann
2, Franziska Emmerling
1
1BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Straße 11, 12489 Berlin, [email protected],
[email protected]; 2Department of Chemistry, Humboldt-University of Berlin, Brook-Taylor-Straße 2, 12489 Berlin
Polymorphism is the property of many inorganic and organic molecules to crystallize in at
least two different crystal structures. Different structures lead to different physicochemical
properties, which are often sought for applications in chemistry or pharmacy. The selective
isolation of a distinct crystalline form remains challenging as the polymorphs vary only
marginally in their values of free enthalpy.[1]
In situ methods allow to detect and identify
transient metastable polymorphs and to elucidate their crystallization mechanism in detail.
Since in situ investigations require sufficient time resolution, we apply X-ray diffraction using
high-energy synchrotron radiation. Combining this technique with Raman spectroscopy
enables to trace the complete crystallization progress promoted by the evaporation of the
solvent. Information about the molecular structure and intermolecular interactions between
the molecules in solutions, amorphous, and crystalline state was obtained.[2]
An ultrasonic
levitator was applied as sample holder to eliminate influences from any solid surfaces on the
crystallization processes.[4]
The setup was used to investigate the crystallization of
paracetamol[3]
and ROY (5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile),[5]
a
precursor of olanzapine. Both substances are known for their distinctive property to form
numerous polymorphic modifications.
[1] J. Bernstein, R. J. Davey, J.-O. Henck, Angew. Chem. Int. Ed. 1999, 3440-3461.
[2] M. Klimakow, J. Leiterer, J. Kneipp, E. Rössler, U.Panne, K. Rademann, F. Emmerling,
Langmuir, 2010, 26, 11233-11237.
[3] P. Espeau, R. Ceolin, J. L. Tamarit, M. A. Perrin, J. P. Gauchi, F. Leveiller, J, J. Pharm.
Sc. 2005, 4, 524-539.
[4] M. C. Schlegel, K. Wenzel, A. Sarfraz, F. Emmerling, Rev. Sci. Instrum., 2012, 83.
[5] L. Yu, G. A. Stephenson, C. A. Mitchell, C. A. Bunnell, S. V. Snorek, J. J. Bowyer, T. B.
Borchardt, J. G. Stowell and S. R. Byrn, J. Am. Chem. Soc., 2000, 122, 585-591.
Surface and optical studies of thin In0.11Ga0.89N SQW layers
S. Alamé
1, A. Navarro-Quezada
1,*, T.Wernicke
2, C. Reich
2, D. Skuridina
2, P. Vogt
2,
M. Kneissl2,3
and N. Esser1
1 Leibniz-Institut für Analytische Wissenschaften - ISAS e.V,
Albert-Einstein-Str. 9, 12489 Berlin 2 Institut für Festkörperphysik, Technische Universität Berlin,
Hardenbergstr. 36, 10623 Berlin
Thin In0.11Ga0.89N single quantum wells (SQW) buried in GaN have been studied by x-ray
photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED),
photoluminescence (PL) and vacuum-UV(VUV)-ellipsometry. The studied thin QW’s are
capped with thin GaN layers of 1 and 3 nm. Careful surface preparation by thermal annealing
between 500°C and 670°C, to obtain clean surfaces without affecting the underlying SQW,
has been performed. It is found that annealing up between 600°C and 670°C in nitrogen
plasma removes the excess of oxygen and carbon from the as-grown surface, while the PL
emission of the SQW is maintained, indicating no indium diffusion out of the QW-layer.
Additionally, measurements with spectroscopic ellipsometry and synchrotron VUV-
ellipsometry in the energy range between 1.5 and 10 eV have been acquired (fig.1), in order
to obtain the optical properties of the thin buried In0.11Ga0.89N-SQW layers as a function of the
cap thickness. The challenges encountered for the interpretation of the acquired spectra on
these complex heterostructures are discussed.
Fig.1. VUV-ellipsometry spectra showing the imaginary part of the pseudo-dielectric function of GaN
and two buried InGaN-SQW layers with 1 nm and 3 nm cap thickness.
5 6 7 8 9 102
3
4
5
6
7
8
9
10
E3
E2
GaN
InGaN-SQW (3nm cap)
InGaN-SQW (1nm cap)
< 2
>
Energy (eV)
E1
Flip-Chip Assembly for Terahertz Electronics
S. Monayakul.*, C. Wang, O. Krüger, N. Weimann
1Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str.4, 12489 Berlin, Germany
* E-mail: [email protected]
For high-frequency applications, miniaturized flip-chip technology is a very attractive packaging solution compared to the wire bonding method because it offers wider bandwidth due to smaller parasitic inductances, good thermal management, better mechanical stability and a smaller package size. In this paper, we describe the development of process technology for small-size (< 10 µm bump diameter) AuSn bump flip-chip transitions. 80/20 AuSn is selected as the bump material due to its proven bonding stability and reliability. Coplanar waveguide lines (CPW) were fabricated by Au electroplating on both quartz or aluminum nitride (AlN) chips and the AlN carrier substrate. The 6 µm thick multilayers of AuSn bumps, with the 80% wt. Au and 20% wt. Sn summary composition, were evaporated on top of the CPW lines of the chip side. The AuSn bumps were structured in an i-line stepper-defined lift-off process. The chip and substrate were bonded by means of an FC-150 commercial flip-chip bonder as illustrated in Figure1 a). The maximum chuck temperature during bonding was 350°C. On-wafer S-Parameter measurements were carried out from DC to 110 GHz with coplanar wafer probes. At 110 GHz an insertion loss of -2dB and a return loss of -15dB were recorded for a device with a total of four transitions in series, as shown in Figure 1a). The simulation shown in Figure 1b) excludes the ohmic losses in the transmission line. A thru-line of equal length as the device (2 mm) yielded approximately 1dB loss. As a result, we can give an upper bound to the insertion loss of less than 0.5dB per transition.
Figure 1: a) cross section the structure measured
b) S21 of the structure in Fig.1a) as a function of frequency: comparison between measurement and simulation results
Risikorouting
Marko Woelki, Ronald Nippold, Michael Bonert und Sten Ruppe
Institut für Verkehrssystemtechnik, Deutsches Zentrum für Luft- und Raumfahrt e. V.
Rutherfordstraße 2, 12489 Berlin-Adlershof
E-Mail: [email protected]
Abstract
The computation of an optimal route for given start and destination in a static transportation
network is used in many applications of private route planning. In this work we focus on route
planning for emergency cars, such as for example police, fire brigade and ambulance. While for
private route planning typical quantities that are minimized are travel time or the length of the path,
the idea is to minimize the risk of a travel time exceeding a certain limit. This is inspired by the fact
that in Germany the emergency cars have to reach the destination within a legal time. We consider
mainly two approaches. The first one takes into account a weekly updated set of floating-car data for
each minute of the week along with current data. Comparing those travel-time data shows the
(historic) variance the associated risk for traveling certain edges of a graph. The second approach
takes into account relevant information to determine the weight, i.e. the desirability of certain edges
of a graph during the minimization procedure. One possible risk factor to be aware of would be a
suddenly jammed single-lane road on which the emergency car has no chance to make use of the
benefits of the siren for instance. The same holds for full-closure situations and railroad crossings.
We present a catalogue of risk factors along with an appropriate algorithm for practical route
planning in emergency situations. Due to the fact that German firemen do not use any automatic
routing, we expect our algorithm to be a major advancement especially for destinations that lie
outside the typical region travelled weekdays. In this case the automatic route planning naturally
goes along with an additional gain of time.
Quantitative NMR-Spektroskopie für die Gasanalytik
Klas Meyer, Michael Maiwald, Ulrich Panne
BAM Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Str. 11, 12489 Berlin
Neben den fest mit der Analytik gasförmiger Proben assoziierten Methoden wie der Gaschromatographie und optisch-spektroskopischen Techniken konnte bereits in frühen Versuchen gezeigt werden, dass auch die NMR-Spektroskopie prinzipiell für die Gasanalytik einsetzbar ist.[1,2] Sie wird jedoch in diesem Bereich selten praktiziert aufgrund der geringen Empfindlichkeit der Methode und der geringen Dichte von Gasen bei Atmosphärendruck.[3] Hier kann durch die Betrachtung bei erhöhten Drücken eine Verbesserung erzielt werden, wofür allerdings über das Routinemaß hinausgehende Ausstattung erforderlich ist. Mit druckfesten Probenröhrchen und Messzellen ist es außerdem möglich Komponenten mit hohen Dampfdrücken im kondensierten Zustand zu untersuchen. Es wurden Verunreinigungen in flüssigen bzw. verflüssigten Kohlenwasserstoff-isomeren von C3 bis C6 mittels quantitativer NMR-Spektroskopie (qNMR) bestimmt. Diese hat als direkte Quantifizierungsmethode den Vorteil Aussagen zur Reinheit der untersuchten Komponenten zu erlauben, ohne das eine Kalibrierung erforderlich ist. Ziel der Untersuchung ist die Anpassung gravimetrischer Herstellungsprozesse von primären Referenzgasgemischen durch genaue Kenntnis des Verunreinigungs-spektrums. Diese Primärnormale werden von der Arbeitsgruppe Gasanalytik der BAM zur Zertifizierung von Sekundärstandards eingesetzt, welche wiederum bei Kalibrieraufgaben in Industrie und Technik Verwendung finden. Weiterhin wurde ein Versuchsaufbau entwickelt um gasförmige Proben mit Drücken bis zu 3 MPa in eine Durchflusszelle im NMR-Spektrometer einzubringen. Dank der gerätetechnischen Entwicklungen zur Verbesserung der Empfindlichkeit ist die moderne NMR-Spektroskopie auch für die quantitative Analytik von Gasgemischen geeignet. Dies konnte durch Bestimmungen von Nachweisgrenzen gezeigt werden. Literatur: [1] A. D. Buckingham, T. Schaefer, W. G. Schneider, J . Chem. Phys. 1960, 32, 1227-1233. [2] W. T. Raynes, A. D. Buckingham, H. J. Bernstein, J. Chem. Phys. 1962, 36, 3481-3488. [3] G. Govil, Appl. Spectrosc. Rev. 1973, 7(1), 47-78.
DNA
- MOLEKÜL MIT STRUKTUR UND STRUKTURGEBENDES MOLEKÜL
Antje D. Mertsch
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH | Institut für Nanometeroptik und Technologie (INT)
Tel. 030 8062-15032 | [email protected]
Das Institut für Nanometeroptik und Technologie (INT) am Helmholtz-Zentrum Berlin für Materialien und
Energie ist international anerkannt für die Berechnung, Herstellung und Metrologie von hochentwickelten
Optiken im Kurzwellenbereich. Erfahrung, Infrastruktur und die hochwertige wissenschaftlich-technische
Ausstattung bilden die Basis für die interdisziplinäre Forschung in den Bereichen Mikro- und
Nanostrukturierung, Oberflächentechnologie, Entwicklung von diffraktiven Optiken und Gittern sowie
Metrologie. In diesem Beitrag werden zwei Patente vorgestellt, die im Zuge der mikro- und
nanotechnologischen Untersuchungen angemeldet wurden und auf der Manipulation geladener
Makromoleküle basieren.
Das Erbgut von Lebewesen ist in Desoxyribonukleinsäuren (DNA) verschlüsselt. Das sind langkettige
Makromoleküle, deren Struktur durch die Kombination der vier Basen Adenin, Thymin, Guanin und Cytosin
charakterisiert ist. Ein im INT entwickeltes Mikro- und Nanofluidiksystem1 ermöglicht die dynamische
Strukturanalyse solcher Moleküle. Kernkomponente ist dabei ein periodisch angeordnetes nanoskaliges
Säulenfeld in einem Mikrofluidikkanal, das zum einen für die Linearisierung des Makromoleküls als
entropische Barriere und zum anderen für die Analyse der DNA als photonischer Kristall wirkt.
Informationen über die strukturelle Zusammensetzung eines einzelnen DNA-Moleküls können auf diesem
Wege ohne aufwendige Vervielfältigungs- und Auftrennungsverfahren gewonnen werden.
Während im ersten Patent die Primärstruktur (Einzelstrangsequenz) der DNA von Interesse ist, wird im
zweiten Patent die Sekundär- und Tertiärstruktur genutzt, um Nanokanäle2 zu erzeugen. Mit einer
entfalteten, in wässriger Lösung negativ geladenen DNA-Doppelhelix wird innerhalb einer entropischen
Barriere und unter Einsatz elektrischer Felder der Verlauf des Nanokanals definiert. Das Gebilde wird
anschließend in SU-8, einem Negativ-Fotolack auf Epoxidharzbasis, eingebettet. Durch Prozessierung des
SU-8 – Belichtung und Temperierung – werden Protonen in Form einer Säure freigesetzt, die die
Vernetzung und Aushärtung der Schicht anregt. Die in dem Einflussbereich des negativ geladenen
Makromoleküls gebildeten Protonen werden durch die Phosphatreste im DNA-Rückgrat gebunden,
wodurch die Polymerisation des Fotolacks in diesem Bereich verhindert wird. Durch Entfernen des nicht-
vernetzten SU-8 und der strukturgebenden DNA aus der ausgehärteten Matrix bleiben Nanokanäle zurück,
die verschieden Einsatzmöglichkeiten als fluidische Strukturen, als optische Wellenleiter oder Luft-/Wasser-
Barrieren bieten.
Die vorgestellten Patente zeigen die Vielfältigkeit der wissenschaftlichen Arbeit des INT. Durch die
interdisziplinäre Verknüpfung und das technologische Know-How in dem Bereich der Mikro- und Nanooptik
ist eine Basis gegeben, um innovative Ideen für ein breites Anwendungsfeld zu entwickeln und umzusetzen.
1 A. Mertsch et. al, Mikro- und Nanofluidsystem zur dynamischen Strukturanalyse von linearen Makromolekülen und
Anwendungen davon, DE 10 2007 027 414 B3 (2007); WO 2008/151611 A1 (2008); EP 2 434 344 A1 (2010) 2 A. Mertsch, O. Mertsch, Molekulares Lithographieverfahren, DE 10 2009 037 011 B3 (2009)
Extract weak Raman signals from huge disturbing backgrounds- Dual wavelength diode lasers for Shifted Excitation Raman
Difference Spectroscopy
Martin Maiwald, Bernd Sumpf, Götz Erbert, Günther Tränkle Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik
Gustav-Kirchhoff-Str. 4 12489 Berlin, Germany
Corresponding Address: [email protected]
Mobile sensor systems for the analysis of materials and substances in application fields such as food safety, medicine, and environmental monitoring become more and more important. Raman spectroscopy based on inelastic optical scattering process generates “fingerprint-like” spectra. This spectroscopic technique is a non-destructive and contactless powerful laboratory tool. Since compact and efficient diode lasers are well-established excitation light sources handheld sensors have rapidly grown, thus bringing Raman spectroscopy out of the laboratory.
However, there are still challenges. The Raman signals are quite weak and often covered by huge disturbing background such as fluorescence, especially generated by organic and biological samples. Moreover ambient light can disturb Raman signals during outdoor measurements. To overcome this drawback the Raman signals had to be extracted from a disturbing background. Here, Shifted Excitation Raman Difference Spectroscopy (SERDS) is a promising technique. Two slightly shifted excitation wavelengths are used, so two slightly shifted Raman spectra are generated. However, the background light remains mainly constant and the signal can be separated by subtract both spectra.
For SERDS, a laser light source is necessary that provides two excitation wavelengths 1 and 2 with a spectral distance of about 10 cm
-1, sufficient for the investigation of most solid and liquid samples.
In this contribution we present dual-wavelength diode lasers with emissions in the visible and near infrared spectral range such as 488 nm, 671 nm, and 785 nm for SERDS. These hybrid and monolithic devices reaches optical output powers up to several hundred milliwatts. Electro-optical and spectral properties are discussed with respect to the requirements for Raman spectroscopy and SERDS. The laser power can be adjusted according to the properties of the substance under study. Raman spectroscopic experiments are presented and demonstrate the suitability of these diode lasers for SERDS. Their compact size, reliable operation and electro-optical efficiencies enable an integration of these devices into portable Raman sensor systems.
Fig.1: Microsystem based dual-wavelength diode laser at 671 nm for SERDS.
Fig. 2: Scheme of a monolithic distributed Bragg reflector (DBR) dual-wavelength diode laser for SERDS.
Online‐Analysenverfahrens mittels XRF zur Bestimmung von Elementgehalten bei der Rückgewinnung von Wertstoffen aus Klärschlammaschen
A. Kühn a, A. Schmalstieg
a, T. Nitsche a
, V. Arkadiev a, R. Gubzhokov b
, und R. Wedell a
a IAP Institut für angewandte Photonik e.V., 12489 Berlin, E‐mail: kuehn@iap‐adlershof.de b IFG Institute for Scientific Instruments GmbH.,12489 Berlin
Der weltweite Abbau von Rohphosphor dient zu 90% der Düngemittelproduktion. Es handelt sich beim Phosphor um eine in Zukunft knapp werdende und nicht erneuerbare Ressource. Phosphor, als für alle Organismen essentieller Bestandteil, kommt in kommunalen Klärschlämmen vor, so dass die Möglichkeit der Rückgewinnung des Phosphors entsprechend eines ressourceneffizienten Urban‐Mining‐Konzeptes nahe liegt. Für Klärschlammaschen aus Monoverbrennungsanlagen stehen heute nasschemische und thermochemische Verfahren zur Verfügung, die Schadstoffe wie Schwermetalle, aus den Klärschlammaschen zu entfernen und die Phosphoranteile im gleichen Prozess in pflanzenverfügbare Verbindungen umzuwandeln. Nur wenn die Konzentrationsparameter entsprechend der Grenzwerte der Düngemittelverordnung erfüllt sind, steht dem Einsatz als Dünger in der Landwirtschaft nichts entgegen. Im Rahmen eines Verbundprojektes konzentrieren wir uns gemeinsam mit der Firma LTB GmbH und der BAM auf einen im BAM‐Technikum etablierten thermochemischen Entfrachtungsprozess. Die Realisierung eines XRF‐Online‐Analysenverfahrens zur Bestimmung von Elementgehalten in Klärschlammaschen ist keineswegs auf diese beschränkt, sondern eignet sich ebenfalls für Prozesse, bei denen die Rückgewinnung von Wertstoffen aus Recyclingströmen im Mittelpunkt steht (z.B. Glasrecycling, Elektroschrott, Rückgewinnung von Seltenen Erdmetallen...), als auch Wareneingangs‐ oder ausgangskontrollen in einer Produktionskette. Der Einsatz der Röntgenfluoreszenzanalyse (XRF) ist für viele Produktionsprozesse die Kontrollmethode der Wahl. Das XRF ‐ Messprinzip besteht in der Identifizierung des relativen Gehalts verschiedener Elemente in einem Material entsprechend der Intensität ihrer Fluoreszenzlinien und der Matrixeinflüsse.
Harte Anforderungen an das Online‐Analysensystem ergeben sich aus den industriellen Einsatzbedingungen hinsichtlich der Prozessatmosphäre, der Temperatur, des Stoffgefüges des Materials (feinpulvrig bis klumpig), der Übertragung von Vibrationen der bewegten Teile, Staubbelastung und elektromagnetische Einflüsse z. B. durch Motoren und Förderbänder. Das Analysesystem wird sowohl modular als auch robust gestaltet sein und erfüllt somit ein wichtiges Kriterium um auch über die Anwendung der Klärschlammaschenanalytik hinaus anwendbar zu sein. Als Ergebnis steht ein Prototyp für die XRF‐Online‐Prozessanalytik für das Verfahren zur thermochemischen
Behandlung von Klärschlammaschen und ähnlichen Stoffströmen zur Verfügung.
IR spectroscopy on mixed functional polymer interfaces to
characterize their switching behavior
Annika Kroning1, Andreas Furchner1, Michael Seeber2, Igor Luzinov2 and Karsten Hinrichs1
1 Leibniz Institut für Analytische Wissenschaften – ISAS – e.V., Albert-Einstein-Str. 9, 12489 Berlin
2 School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634-0971
Functional polymer interfaces are thin layers (<30 nm) of responsive polymers and have been
studied intensively over the past years [1]. The functionality is based on the fact that the
polymer chains are densely end-grafted to the substrate, forcing them to stretch away from the
substrate like bristles on a brush. In this system, the chains respond collectively to an external
stimulus, e.g. a change in temperature (Figure 1).
In this study, a temperature-responsive polymer – Poly(N-isopropylacrylamide) [PNIPAAm] – is
used. Its response takes place around the lower critical solution temperature (LCST) of 32°C,
therefore it is of special interest for biomedical applications. The brushes were synthesized by
the “grafting to” method. A copolymer consisting of PNIPAAm and an anchoring polymer
(Polyglycidylmethacrylate, [PGMA]) was grafted in one step instead of the traditional 2-step
synthesis, where the anchoring layer is grafted first, followed by the polymer.
Infrared Spectroscopic Ellipsometry (IRSE) is used to study the structure and responsive
behavior of these interfaces. We are particularly interested in the polymer-polymer and polymer-
water interactions and how these interactions change when the stimulus is applied. A specially
designed in-situ cell enables us to probe the solid-liquid interface of the polymer in contact with
solution [2].
T > LCST
T < LCST
Substrate Substrate
Figure 1: Scheme of the switching behavior of a PNIPAAm brush in water.
[1] Chen et al., Progress in Polymer Science 2010, 35, 94-112. [2] Furchner et al., Thin solid films 2013, 541, 41-45.
M. Kost; Prof. J.-C. Freytag, Ph.D.; ({kost, freytag}@informatik.hu-berlin.de)
PRECIOSA PeRA: Practical Enforcement of Privacy Policies in Intelligent
Transportation Systems
POSTER-ABSTRACT
Designing and implementing co-operative mobile systems that comply with current
and future privacy regulations is a great challenge. Evolving Intelligent Transportation
Systems (ITS) provide co-operative applications which implement an improved
functionality such as enhanced travel services, driving support, and transportation
optimization. These applications exchange information about participating individuals
(e.g., vehicle owners and drivers); thus, impacting the privacy of persons.
Uncontrolled information flows potentially allow for privacy infringements (e. g.,
generating movement profiles).
In order to address privacy issues in ITS we must incorporate mechanisms providing
the individual for controlling his/her privacy. Existing approaches only consider
controlling the event of data access using a central instance. In contrast, we consider
implementing individual privacy requirements for the complete data flow of distributed
systems. We analyzed and applied domain independent privacy principles on the ITS
domain; especially the functional requirements and processes. Thereby, one of the
identified challenges, which we address, is to prevent an attacker from circumventing
the defined privacy requirements within a distributed system. For instance, if we
apply a policy enforcement mechanism we have to guarantee that the policies, which
describe the privacy requirements of the individuals, as well as the application code
will not be manipulated. Additionally, we have to guarantee the privacy-compliant
execution of applications that consists of (standard and user-defined) operations.
Based on approaches such as Hippocratic databases, we designed and implemented
the privacy middleware PRECIOSA Privacy-enforcing Runtime Architecture (PeRA).
With PeRA we provide a holistic privacy protection approach, which implements
user-defined privacy policies. A data-centric protection chain ensures that ITS
components process data according to attached privacy policies. PeRA instances,
which are deployed on ITS nodes, constitute a distributed privacy middleware, which
evaluates privacy policies to mediate data access by applications. The PeRA
architecture includes an integrity protection layer to create a distributed policy
enforcement perimeter between ITS nodes. We implemented the PeRA architecture
as a proof-of-concept prototype.
Abstract for Adlershofer Forschungsforum (AFF)2013
IPA-free textured a-Si:H/c-Si heterojunction solar cells
exceeding 20% efficiency
Jan Kegel1,2
, Heike Angermann2 , Uta Stürzebecher
3, Erhard Conrad
2, Lars Korte
2, Bert
Stegemann1
1 HTW Berlin - University of Applied Sciences, Wilhelminenhofstr. 75a, 12459 Berlin, Germany
2 Helmholtz-Zentrum Berlin (HZB), Institut für Silizium-Photovoltaik, Kekuléstraße 5, 12489 Berlin, Germany
3 CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt,
Germany
High-efficiency silicon heterojunction solar cells are composed of thin amorphous silicon
layers deposited on crystalline silicon wafers. This configuration enables excellent surface
passivation and thus high open-circuit voltages. Further improvement can be achieved by
proper texturization of the Si wafer leading to increased short-circuit current densities and
thus higher energy conversion efficiencies [1].
A systematic step by step comparison of amorphous/crystalline heterojunction (a-Si:H/c-Si)
solar cells textured in isopropanol(IPA)-free KOH solution and in IPA-containing KOH
solution was performed in order to investigate the potential and limitations of IPA-free solar
cell processing for reaching high efficiencies. As a result, a-Si:H/c-Si solar cells on n-type
substrate, textured in IPA-free solution and in IPA-containing solution, both with conversion
efficiencies exceeding 20 % are obtained. These values represent a considerable improvement
over our previously reported best cell efficiencies for cells with a-Si:H(i) buffer layer. They
were achieved by thorough optimization of the surface texture [2], the pyramid morphology
[3], the a-Si:H/c-Si interface passivation [4,5], and the thickness of the intrinsic a-Si:H front
layer [6,7], resulting in improved open-circuit voltages and fill factors. Thus, solar cells
fabricated on IPA-free textured wafers can compete with those processed on wafers textured
in conventional IPA-containing alkaline solution and are an attractive alternative for industrial
production due to their better process control, lower environmental impact and lower costs
[6,7].
[1] http://panasonic.co.jp/corp/news/official.data/data.dir/2013/02/en130212-7/en130212-7.html
[2] B. Stegemann, J. Kegel, O. Gref, U. Stürzebecher, A. Laades, K. Wolke, C. Gottschalk, H. Angermann: Proc.
27th European Photovoltaic Solar Energy Conference, 2012, pp. 547 – 551.
[3] J. Kegel, H. Angermann, U. Stürzebecher, B. Stegemann: Energy Procedia 38 (2013) 833–842
[4] B. Stegemann, J. Kegel, M. Mews, E. Conrad, L. Korte, U. Stürzebecher, H. Angermann: Energy Procedia
38 (2013) 881–889
[5] M. Mews, TF.Schulze, N. Mingirulli, L. Korte: Applied Physics Letters 102 (2013) 122106
[6] J. Kegel, H. Angermann, U. Stürzebecher, E. Conrad, L. Korte, B. Stegemann: Proc. 28th European Photo-
voltaic Solar Energy Conference (2013), contribution 2BV.1.17
[7] J. Kegel, H. Angermann, U. Stürzebecher, E. Conrad, M. Mews, L. Korte, B. Stegemann: submitted to
Applied Surface Science (2013).
Probing the optical mode density with nanometer resolution
Günter Kewes, Andreas W. Schell, Philip Engel, Thomas Aichele, Oliver Benson, Humboldt Universität zu Berlin,
Newtonstrasse 15, 12489 Berlin, Germany, [email protected]
Tobias Hanke, Albert Leitenstorfer Universität Konstanz, 78457 Konstanz, Germany
Rudolf Bratschitsch, WWU Münster, 48149 Münster, Germany
One of the most important numbers in optics is the local density of states (LDOS). It is present in Planck’s formula of black body radiation and in Fermi’s Golden Rule. Essentially the LDOS describes the lifetime of the excited state of quantum emitters or in other words the number of virtual photons interacting with the emitter.
However, the measurement of the LDOS is still demanding. Scanning near field microscopes (SNOM) collect light
through a small aperture or scatter light out of the near field to detect it in the far-field. This approach has the drawback
that it is not independent of the illumination of the measured sample, whereas the LDOS is independent. In principle
black body radiation would be needed for illumination, in other words: all possible modes have to be populated by real
photons.
In order to circumvent this problem we make use of the effect of lifetime changes associated with LDOS changes more
directly:
Due to its stability at ambient conditions, long (and easy to measure) lifetime and small dimensions we use single
nitrogen vacancy (NV) centers in nanodiamond as a quantum probe to map out the LDOS of nanostructures.
In a first basic experiment nanodiamonds with only one NV-center are nano-manipulated via atomic force microscope
to designated positions on a plasmonic nanoantenna. On each position the lifetime is measured. By this a rough map of
the LDOS is produced. Recently we even realized an automated version of this approach by gluing a nanodiamond onto
a tip of an AFM.
Raman micro-spectroscopy in combination with scattering methods to study silica
in plant materials
Maike Joester1,2
, Janina Kneipp1,Franziska Emmerling
2
1Department of Chemistry, Humboldt Universität zu Berlin, Germany
2Federal Institute for Materials Research and Testing, Berlin, Germany
To plants, silica is available due to its presence in soil and dust. This inorganic component is known
to increase yields of crops and to mitigate biotic and a-biotic stresses by improving plant fitness.
The absorption of silica might involve the transport from the roots through the transpiration stream
to the epidermis and epidermal features.[1]
Although there are many studies about silica bodies [2]
and the presence of silica in biochemical and biophysical processes in general, most of the
mechanisms leading to silicification are not fully understood. Therefore, we focus on the
investigation of plant cells from cell cultures and pollen as a model system to find a connection
between the molecular composition and the microscopic and macroscopic structure of a plant cell
during the silicification process. To achieve this, we combine physiological experiments with cells
and pollen with different techniques that provide data on molecular structure of the inorganic silica,
the complex organic plant material, and the cellular morphology. The challenge of our project is to
combine the information from spatially resolved optical microspectroscopy, specifically Raman
scattering with X-ray scattering techniques such as Wide and Small Angle X-Ray Scattering
(WAXS and SAXS) to study inorganic material in a complex biomatrix. Up to now a combination
of both methods was only possible for very well-defined molecules [3]
.
In our poster, we present experiments with germinated pollen grains from different species. We
discuss imaging results of the germination process that we obtained by Raman scattering, thereby
extending the information of previous data [4]
. Furthermore, we present first data of our WAXS
experiments with horsetail done at µ-Spot beamline of BESSY II, Berlin. These results demonstrate
that our proposed experimental approach is feasible. References:
[1] P. Bauer, R. Elbaum, I. M. Weiss, Plant Science: An International Journal of Experimental
Plant Biology, 180, 746-756 (2011).
[2] C. J. Prychid, P. J. Rudall, M. Gregory, The Botanical Review, 69, 377-440 (2003).
[3] M. Klimakow, J. Leiterer, J. Kneipp, E. Rossler, U. Panne, K. Rademann, F. Emmerling,
Langmuir, 26, 11233-11237 (2010).
[4] F. Schulte, U. Panne, J. Kneipp, Journal of Biophotonics, 3, 542-547 (2010).
[1] S. Nakamura et al., Jpn. J. Appl. Phys. 35, L74 (1996)
[2] D. Scholz et al., Opt. Express 16, 6846 (2008)
[3] Vurgaftman et al., IEEE J. Sel. Top. Quantum Electron. 3, 475 (1997)
Lateral near field filamentation of violet broad area (Al,In)GaN
laser diodes J. Jeschke
1, U. Zeimer
1, L. Redaelli
1, S. Einfeldt
1, M. Kneissl
1,2 and M. Weyers
1
1Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin
2Institut für Festkörperphysik, Technische Universität Berlin, 10623 Berlin
Following the first demonstration by Nakamura et al. [1] in 1995, today (Al,In)GaN-based laser diodes
(LDs) have found their way into various commercial applications. In order to achieve high optical
powers broad area laser structures are required to limit the current density and prevent catastrophic
optical mirror damage. However, if the cavity width exceeds 2 µm, the beam quality is deteriorated
due to the formation of several irregular intensity maxima and minima in the lateral near field, called
filaments. These are caused by refractive index variations due to inhomogeneous carrier density,
heating or spatial hole burning [2]. In this study we examine the correlation between basic laser
parameters (e.g., threshold current density, slope efficiency, etc.), filamentation and homogeneity of
the active region.
Measurements were carried out on gain-guided edge emitting laser diodes with a lasing wavelength of
410 nm and light output powers of up to one Watt. Six laser bars from different regions of the same
wafer, each bar with several LDs with different stripe widths, ranging from 5 µm to 40 µm, were
compared. Threshold current density, slope efficiency, wavelength, spectral linewidth and lateral near
field were measured under pulsed current operation (300 ns, 1 kHz). The near field was projected on a
CCD array. Furthermore, the cathodoluminescence
(CL) of four bars was mapped over an area of
50x50 µm² at 80 K.
LDs from the same bar were found to have similar
near fields with comparable numbers of filaments
per stripe width. In contrast, LDs from different
bars differed significantly in number and width of
filaments (cf. Fig. 1). Bars with stronger
filamentation (more filaments per stripe width)
showed a higher threshold, lower slope efficiency,
a redshifted emission and broader linewidth.
CL maps revealed much higher fluctuations of the
quantum well band gap energies for bars that
showed stronger filamentation in their near field.
Vurgaftman et al. studied theoretically the
influence of band gap energy fluctuations on
threshold, slope efficiency and emission
wavelength and predicted the same trends as
observed in this work [3]. On the other hand, band
gap inhomogeneities can explain stronger filamentation since composition or thickness fluctuations
enhance refractive index variations, variations of the injected carrier density and gain variations, which
are the main driving forces of filamentation.
Therefore, homogeneity of the active region is a very important aspect for optimization of both basic
laser parameters and beam quality.
0 20 40 60 80
lateral position (a.u.)
inte
nsity (
a.u
.)
D4
D8
D12
D16
D20
D24
0 20 40 60 80lateral position (a.u.)
inte
nsity (
a.u
.)
D4
D8
D12
D16
D20
D24
Fig. 1: Lateral near fields of LDs from (a)
bar 1 (many small filaments) and (b) bar 2
(fewer, broader filaments)
Verfolgung mechanochemischer Synthesen durch in situ Röntgendiffraktometrie
Manuel Wilke1, Franziska Fischer1, Lisa Tröbs1, Klaus Rademann
2, Franziska Emmerling
1
1BAM Bundesanstalt für Materialforschung und ‐prüfung, Berlin 2Institut für Chemie, Humboldt Universität zu Berlin, Berlin
Die Entwicklung neuer Materialien, die mit interessanten Eigenschaften neue Anwendungsfelder erschließen, ist eine der Hauptaufgaben der Festkörperchemie. Zwei populäre Beispiele stellen die metallorganischen Hybridsysteme und Cokristalle dar. In metallorganischen Verbindungen sind organische Moleküle meist über polare, funktionelle Gruppen an ein oder mehrere Metallionen koordiniert. Sie besitzen außergewöhnliche magnetische und konduktive Eigenschaften und finden Anwendung in den Gebieten des Wirkstofftransports, der Katalyse, der Gasspeicherung und ‐reinigung sowie als Nanoreaktoren.[1] Die Synthese pharmazeutischer Cokristalle eröffnet die Möglichkeit, die Löslichkeit, die Bioverfügbarkeit oder die Stabilität des pharmazeutisch aktiven Bestandteils (API, active pharmaceutical ingredient) zu erhöhen.[2,3] Auch wenn es üblich ist, metallorganische Verbindungen und Cokristalle auf solvothermalem Weg herzustellen, stellt die Mechanochemie eine aussichtsreiche Alternative für die Synthese solcher Materialien dar. Bei dieser Methode werden hohe Ausbeuten erzielt und nur wenig oder sogar kein Lösungsmittel verbraucht. Trotz einiger, plausibler Vorschläge gelten die der mechanochemischen Synthese zu Grunde liegenden Mechanismen als nicht aufgeklärt.[4]
Für die Entwicklung rationaler Synthesen ist es notwendig, die Bildung der Produkte zu verstehen. Dafür werden Methoden benötigt, mit denen man den Bildungsprozess in situ verfolgen kann. Die Röntgendiffraktometrie stellt für kristalline Festkörpermaterialien eine ausgezeichnete Methode dar, da Reaktionsverläufe zeitaufgelöst verfolgt werden können. Somit ist es möglich, amorphe und kristalline Intermediate zu identifizieren. Vor diesem Hintergrund wird eine Methode präsentiert, bei der mechanochemische Reaktionen pseudo in situ mittels Synchrotron Röntgendiffraktometrie verfolgt werden können. Als Modellsysteme wurden Übergangsmetallphosphonate und Cokristalle von Theophyllin untersucht.
[1] G. Ferey, Chem. Soc. Rev. 2008, 37, 191‐214. [2] D.R. Weyna, T. Shattock, P. Vishweshwar und M.J. Zaworotko, Cryst. Growth Des. 2009, 9,
1106‐1123. [3] A. Delori, T. Friscic und W. Jones, Crystengcomm 2012, 14, 2350‐2362. [4] P. Balaz, Mechanochemistry in Nanoscience and Minerals Engineering, Springer‐Verlag, Berlin
Heidelberg, 2008.
Blick in die Kammer, die die Proben
Proben im Synchrotronstrahl positio-
niert.
ReferenzprobenfreieMaterialanalytik nano- undmikroskaliger Systememit
verschiedenen Verfahren der Röntgenspektrometrie
P. Hönicke, I. Holfelder, C. Streeck, A. Nutsch, M. Gerlach, J. Lubeck, M. Müller,
B. Pollakowski, R. Unterumsberger, J. Weser and B. Beckhoff
Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587 Berlin, Germany
E-mail: [email protected]
Die Arbeitsgruppe Röntgen- und IR-Spektrometrie der PTB bietet
Dienstleistungen, Forschung und Entwicklung für röntgenspektros-
kopische Messtechnik mit Synchrotronstrahlung an. Die entwickel-
ten analytischen Methoden und die kalibrierte Instrumentierung
ergänzen die derzeitigen Ausstattungen aus der Industrie und kom-
merzieller Laborbereiche.
Es werden verschiedene Strahlrohre im PTB-Laboratorium und die
BAMline bei BESSY genutzt. Photonenenergien zwischen 78 eV und
60 keV stehen für die verschiedenen Verfahren zur Untersuchung
von Fragestellungen aus der Nanotechnologie, der Oberflächen– und
Grenzflächenanalytik, der Forschung zu Energiematerialien und der
Medizindiagnostik zur Verfügung. Die zu bestimmenden physikali-
schen und chemischen Eigenschaften wie Dimensionen, Zusammen-
setzung und Verunreinigungen werden durch verschiedene röntgen-
spektrometrische Verfahren und unter Verwendung kalibrierter
Instrumentierung zugänglich gemacht.
Für die Forschungsvorhaben wird eine neue Generation von Instrumentierung in den Laboratorien
der PTB verwendet. (siehe Abb.) Die Instrumentierung wurde und wird erfolgreich mittels Technolo-
gietransfer in andere Forschungseinrichtungen etabliert so zum Beispiel an das BLIX der TU Berlin.
A multiplex microarray for environmental analysis
Robert Höhne, Stefanie Gärtner, Rudolf J. Schneider
BAM Federal Institute for Materials Research and Testing, D-12489 Berlin, Germany
Water quality is an issue with relevance for the whole society, making it necessary to routinely
monitor contaminants and micropollutants in water samples. The chief advantage of
microarray technology, one of the fastest growing fields in analytical science, is the possibility
to detect multiple analytes in parallel. Protein microarrays for environmental analyses have
demonstrated their potential in various studies1-3
. Especially developments of biological and
chemical technologies in the last decade have made these analytical tools become miniaturized,
integrated, quantitative, highly sensitive, and high-throughput4. Protein microarrays, such as
antibody-based hapten microarrays, are therefore a powerful alternative to traditionally
employed methods3. While analyses with conventional immunoassays, e.g. ELISAs, allow
only the detection of a single compound at a time, quantification with GC-MS and LC-MS is
laborious and requires expensive equipment and well-trained personnel. The establishment of a
microarray combining robust and valid results and a multianalyte approach could change
environmental monitoring radically.
Here, we present a segmented competitive hapten microarray (Fig. 1) for the parallel quanti-
fication of selected anthropogenic markers in water samples. Analyte protein conjugates were
synthesized and immobilized onto 3D-NHS activated surfaces. These covalently bound
analytes and the analytes in the sample compete for the antigen binding sites of the analyte-
specific antibodies. Bound antibodies are visualized by antibody-fluorophore conjugates.
Calibration curves were plotted for the optimized assays and the characteristic sigmoidal curve
forms were obtained. Test midpoints and measurement ranges were determined. In this study
we show that multianalyte microarrays can be established with polyclonal antibodies what, to
the best of our knowledge, had not been described previously.
Furthermore we show the feasibility of our approach to detect residues in water samples in
parallel. The established microarray forms the basis for multiple applications and further
improvements.
Fig. 1: Setup of the multiplex hapten microarray
1. Gao, Z. et al., Immunochip for the detection of five kinds of chemicals: Atrazine, nonylphenol, 17-β-estradiol, paraverine and chloramphenicol. Biosens. & Bioelectron, 2009, 24, 1445-1450. 2. Belleville, E. et al. Quantitative microarray pesticide analysis. J. Immunol. Methods, 2004, 286, 219-229. 3. Fan, Z. et al., Sensitive immunoassay detection of multiple environmental chemicals on protein microarray using DNA/dye conjugate as a fluorescent label. J. Environ. Monit., 2012, 14,1345-1352. 4. Seidel, M. et al., Automated analytical microarrays: a critical review., Anal. Bioanal. Chem., 2008, 391, 1521-1544
Contact: [email protected]; Phone: + 49 30 8104 5821
Quantification of Acid Sites on
Aluminum Hydroxide Fluoride Surfaces by 15N NMR Spectroscopy
F. Hemmann [a,b]
, E. Kemnitz [a]
, C. Jäger [b]
a Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße, D-24892, Berlin,
Germany.
b BAM Federal Institute for Materials Research and Testing, Division 1, Richard Willstaetter Straße 11,
D-12489 Berlin, Germany
Email: [email protected]
Acid solids are an important class of heterogenous catalysts which are widely used for
petrochemical processes. Due to acid Lewis and Brønsted sites at their surfaces, they are capable
of catalyzing various reactions. Related to the concepts of green chemistry of avoiding waste
and toxic by-products they become nowadays increasingly important for fine chemicals 1. The
type and concentration of acid surface sites, Lewis and/or Brønsted sites, strongly influence the
resulting product distribution. Despite various efforts, the simultaneous quantification of Lewis and
Brønsted sites is still a severe problem and topic of current research.
In our investigation we used 15
N solid state NMR with pyridine as a probe molecule. Pyridine is often
used for NMR as well as for FTIR spectroscopy, because Brønsted and even different Lewis sites can
be distinguished. We present a time-optimized NMR quantification procedure for acid site
concentrations 2. The proposed time-saving procedure combines (i) the signal-to-noise ratio
optimized 15
N MAS NMR measurement with an (ii) appropriate T1 intensity correction procedure
using a proposal by Torchia 3; the T1 intensity correction procedure avoids a complete T1
measurement.
A series of adjustable bi-acidic (Lewis and Brønsted) solid catalysts aluminum hydroxide fluorides
were investigated. They were synthesized according the fluorolytic sol-gel synthesis 4. By this
synthesis can the ratio of fluoride to hydroxyl groups be varied and so the concentration of Lewis to
Brønsted acid sites in the aluminum hydroxide fluorides can be fine tuned. Thus, this substance class
is suitable to act as a model system for investigating acidity on solid surfaces.
Correlations between the detected acid site concentrations by 15
N MAS NMR and the catalytic
activity were found for these catalysts.
References:
(1) Corma, A.; García, H. Chem. Rev., 2003, 103, 4307, DOI: 10.1021/cr030680z. (2) Hemmann, F.; Scholz, G.; Scheurell, K.; Kemnitz, E.; Jaeger, C. J. Phys. Chem. C, 2012, 116 , 10580,
DOI: 10.1021/jp212045w. (3) Torchia, D. A. J. Magn. Reson. 1978, 30, 613, DOI: 10.1016/0022-2364(78)90288-3. (4) Rüdiger, S.; Kemnitz, E. Dalton Trans., 2008, 9, 1117, DOI: 10.1039/B716483A.
Diffuse EUV Scattering from Rough
Multilayer Mirrors
Anton Haase, Victor Soltwisch, Christian Laubis, Frank Scholze
Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin
Multilayer systems have been of great interest over the past decades. The reflectivity of classical mirrors near normal incidence is severely diminished and eventually vanishes when moving towards shorter wavelength, especially in the extreme ultraviolet and towards the x-ray regime. The stacking of multiple layers in such a way that the small reflectivities of the single surfaces interfere constructively causes strongly enhanced reflectivity. This principle of operation introduces a strong angle and wavelength dependence on the reflectivity. Today, the semiconductor industry drives the development of high reflective multilayer coatings for the use of EUV light in the next-generation optical lithography. Lenses in classic lithography systems operating at 192 nm wavelength are replaced by multilayer mirrors optimized for high reflectivity at 13.5 nm wavelength.
In the presented work we characterize high-quality Mo/Si multilayer mirrors with reflectivities well above 60% with respect to interface roughness. These imperfections are an important loss mechanism for specular reflectivity and cause
diffuse scattering. We use this diffusely scattered light as a tool to study the interface morphology. The BESSY II electron storage ring serves as our EUV light source. The soft X-ray beamline at our PTB laboratory provides a highly collimated synchrotron radiation beam with a tunable wavelength range between 0.7 nm – 35 nm. We demonstrate that dynamic multiple reflections due to the multilayer stacking have to be considered in order to deduce roughness information from the off-specular scattering. The power spectral density can then be extracted with respect to this multilayer enhancement factor independent of the measurement geometry. A comparison to the GISAXS method with harder X-ray wavelengths well below 1 nm support our data.
contact: [email protected] Adlershofer Forschungsforum | 12.11.2013
Fig. 2. Diffuse scattering intensity maps represented in
reciprocal space recorded in different
measurement geometries. The off-specular
scattering originates from interface roughness of
the multilayer.
Fig. 1. Mo/Si multilayer mirror on silicon
waver substrate.
Effect of carrier gas on the optical and structural properties of GaN
E. Gridneva1*
, E. Richter1, M. Feneberg
2, M. Weyers
1, G. Tränkle
1
1Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnick, Gustav-Kirchhof-
Straße 4, D-12489 Berlin, Germany. 2Institut of Experimental Physics, Otto-von-Guericke Universität Magdeburg,
Universitätsplatz 2, 39106 Berlin, Germany
*E-Mail: [email protected]
Hydride vapor phase epitaxy (HVPE) is a promising technique and being actively developed
for growth of GaN substrates which are demanded for fabrication of e.g. light emitting diodes
and laser diodes in the short wavelength range. The main reaction providing GaN growth in
HVPE is that of ammonia and gaseous GaCl, with hydrogen and nitrogen being the usual
carrier gases. We have studied the impact of carrier gas composition using mixtures of H2 and
N2 on the growth process. Experiments were carried out in AIXTRON vertical HVPE reactor
using 3.5 µm GaN substrates grown on sapphire templates by MOVPE (metal-organic vapor
phase epitaxy). In-situ reflectometry, Nomarski microscopy, photoluminescence and X-ray
diffraction were used to characterize the grown layers. After readjusting NH3 and GaCl partial
pressures according to the simulated gas-flow dynamics, a H2 fraction in the range of 0-60 %
was found to be favorable regarding the layer quality. Under these conditions it was possible
to grow 100 µm thick GaN films without cracks and at a high growth rate of about 240-300
µm/h. X-ray diffraction measurements of 002 and 302 rocking curves on 100 µm thick films
revealed dislocations densities of 108 cm
-2. 70% of H2 resulted in cracks and damaged film
surface, possibly due to enhanced GaN decomposition, which would also explain the
decreased growth rate of only around 150 µm/h. Broadened X-ray rocking curves indicated a
higher dislocation density of about 7∙109 cm
-2. In general, H2 is not only a carrier gas, but also
a reaction product in GaN growth and thus participates in the growth process. The role of H2
in the surface kinetics and its impact on layer quality and optical properties will thus be
discussed.
Acknowledgments: this work was supported by Federal Ministry of Education and Research,
projects 01BU0621 and 16BM1202.
Manipulating a Covalent Chemical Equilibrium by Light
R. Göstl and S. Hecht*
Laboratory of Organic Chemistry and Functional Materials, Department of Chemistry,
Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany
Since its discovery, the Diels-Alder reaction has evolved to one of the most powerful
synthetic protocols for the assembly of complex six-membered ring-systems in the toolbox of
the organic chemist.[1]
As it proceeds in a bimolecular fashion without the need for catalysts
and without the loss of small molecules, the Diels-Alder reaction features intrinsic full
reversibility by dynamically equilibrating if the right conditions are employed. Manipulating
and controlling chemical equilibria is amongst the most prominent challenges for the design
of artificial molecular machines and smart materials, and as such a key element for chemical
systems of the future.[2]
Here, we show an attempt for exerting light gated control over the
equilibrium between diene, dienophile and adduct of a Diels-Alder reaction employing a
photochromic diarylethene as the diene component.
As furan derivatives are known to readily undergo reversible Diels-Alder reactions with a
variety of dienophiles,[3]
a dimethylfuryl residue was incorporated into a diarylcyclopentene
photoswitch as aryl moiety employing a novel, straightforward aldol-type synthetic approach.
The newly designed furyl-thienylcyclopentene proved its potential of exerting full control
over the reaction system, employing maleimide as the dienophile, through reversibly locking
either the diene or the adduct by irradiation with light (Scheme 1).
Scheme 1. Photocontrolling the Diels-Alder reaction between maleimide and a furyl-thienylcyclopentene.
[1] F. Fringuelli, A. Taticchi, The Diels-Alder Reaction: Selected Practical Methods, John Wiley And Sons,
2002.
[2] A. Coskun, M. Banaszak R. D. Astumian, J. F. Stoddart, B. A. Grzybowski Chem. Soc. Rev., 2012, 41, 19-
30.
[3] (a) J. A. Syrett, C. R. Becer, D. M. Haddleton Polym. Chem., 2010, 1, 978-987; (b) M. A. Tasdelen Polym.
Chem., 2011, 2, 2133-2145.
Humboldt-Universität zu Berlin, Exzellenzcluster Bild Wissen Gestaltung, Basisprojekt Gestaltung von Laboren Postanschrift: Unter den Linden 6, D-10099 Berlin; Besucheradresse: Sophienstraße 22a, D-10178 Berlin
Principal Investigators: Finn Geipel, Charlotte Klonk, Norbert Koch, Jürgen P. Rabe, Helmut Staubach
Researchers: Ronald Göbel, Sabine Hansmann, Christina Landbrecht, Verena Straub
Das Exzellenzcluster Bild Wissen Gestaltung – Gestaltung von Laboren
Bild Wissen Gestaltung ist ein Zusammenschluss aus 25 unterschiedlichen Wissenschafts- und Gestaltungs-disziplinen, welche in über 20 verschiedenen Projekten an der Erforschung von Gestaltungsprozesse in den Wissenschaften arbeiten. Im Projekt Gestaltung von Laboren wird der Laborraum aus den unterschiedlichen Perspektiven der beteiligten Fachbereiche Physik, Chemie, Kunstgeschichte, Architektur und Design analysiert. Die Ergebnisse dieser inter-disziplinären Arbeit bilden eine Grundlage für die Planung des Forschungsneubaus IRIS Adlershof. Vorgehensweise
• historische Aufarbeitung von Labordarstellungen • Vergleichende Analyse aktueller Laborbauten in Europa, USA und Asien • Befragung von Labornutzern hinsichtlich ihres Arbeits- und Kommunikationsverhalten • Erarbeitung von Leitlinien für einen interdisziplinären Laborbau
Die Entwicklung von Laboren über die Jahrhunderte zeugt von der Bedeutung der Wissenschaft in der Gesellschaft und über deren Selbstverständnis.
(Links: Analytisches Labor an der Universität Gießen, Lithografie nach Wilhelm Trauschold 1842; Mitte: Kidder Chemical Laboratories MIT Cambridge USA 1867; Rechts: Frick Chemistry Laboratory 2013)
Zur Untersuchung von Raumkonzepten werden bestehende Labore fotografisch aufgenommen und vermessen. Anhand von maßstabsgerechten Zeichnungen können Aussagen zur aktuellen Raumverteilung- und -nutzung getroffen werden. Diese Daten bilden die Grundlage für eine Laboroptimierung oder die
Neuplanung eines Labors. (Chiba University 2013, Foto: Sabine Hansmann, Zeichnung: Sabine Hansmann, Laura Enghusen/BWG)
Das Exzellenzcluster Bild Wissen Gestaltung als Modell für interdisziplinäre Zusammenarbeit
Zur Planungsunterstützung empfiehlt das Basisprojekt für das IRIS-Raumprogramm: • Überdenken herkömmlicher Strukturelemente von Laborbauten um der interdisziplinären Ausrichtung des
IRIS Adlershof eine optimale Arbeitsumgebung zu bieten • Orientierung an den Bedürfnissen und Erfahrungswerten von Nutzern aus Forschungseinrichtungen, welche im
Rahmen des Projekts untersucht wurden • Vorschläge für eine innovative architektonische Verschränkung unterschiedlicher Arbeitsbereiche (Büro, Labor
und Begegnungsflächen)
in Kooperation mit
Hapten design for the production of antibodies against small molecules
Gärtner, S.*1,2
, Canitz, C.2, Garbe, L.-A.
2, Schneider, R. J.
1
1 BAM Federal Institute for Materials Research and Testing, Berlin, Germany
2 Technische Universität Berlin, Berlin, Germany
Immunoassays for small molecules display valuable tools in a variety of applications, including
diagnostics, food and environmental analysis. However, highly selective and sensitive antibodies are
today only available for a limited number of analytes. Consequently the development of antibodies for
the remaining group of interesting small molecules is still an important field of research in order to be
able to exploit the full potential of immunoanalytics.
In contrast to natural antigens, molecules of less than 1000 Daltons have to be conjugated to suitable
carrier molecules to elicit an immune response in mammals. In some cases the proteins can directly be
bound to a functional group of the analyte, however often an appropriate derivative, called hapten,
needs to be designed. The strategy for the conjugation is thereby critical for the selectivity and affinity
of the generated antibodies.
We present our approach to design haptens and produce antibodies for the bile acid isolithocholic acid
(ILA, Fig. 1A) and the widely used plasticizer diisononyl 1,2-cyclohexane-dicarboxylic acid (DINCH,
Fig. 1B). Both analytes are interesting markers for clinical [1, 2] and environmental analysis [3, 4].
ILA was directly conjugated to the immunogenic carrier protein bovine serum albumin (BSA) via its
carboxyl moiety, DINCH in contrast has no functional group for coupling. Thus two different DINCH
derivatives, hapten 1 (Fig. 1C) and hapten 2 (Fig. 1D) were designed, synthesized and conjugated to
BSA. The functional groups for conjugation were introduced at two distinct positions of the analyte
structure, so that different parts of the hapten structure are presented on the carrier. Each of the three
BSA conjugates was used to immunize two or four rabbits, respectively. Highly selective antibodies
for ILA and the DINCH haptens 1 and 2 were obtained. The high affinity of the antibodies allowed the
development of direct competitive enzyme-linked immunosorbent assays for ILA, DINCH hapten 1
and DINCH hapten 2 with test midpoints around 1 µg/L. Contrary to expectations no binding of the
analyte DINCH to the antibodies against DINCH hapten 1 or hapten 2 could be detected. These
findings might be explained by a poor hapten design, however there are challenges arising from the
isomeric composition and the low water solubility of DINCH.
[1] Danielsson, H., Sjovall, J., Annu. Rev. Biochem. 1975, 44, 233-253.
[2] Silva, M. J., Jia, T., Samandar, E., Preau Jr, J. L., Calafat, A. M., Environ. Res. 2013.
[3] Chaler, R., Simoneit, B. R., Grimalt, J. O., J. Chromatogr. A 2001, 927, 155-160.
[4] Nagorka, R., Conrad, A., Scheller, C., Sussenbach, B., Moriske, H. J., Int. J. Hyg. Environ. Health 2011, 214,
26-35.
*Contact: [email protected]
Separation effects caused by the dried-droplet sample preparation for MALDI mass
spectrometry of synthetic polymers
Gabriel, S., Berlin/D, Weidner, S., Berlin/D, Panne, U., Berlin/D, Schwarzinger, C. Linz/A
Stefan Johannes Gabriel, BAM, Richard-Willstätter-Str. 11, Berlin/D
Introduction
Since the dried droplet sample preparation technique is easy to handle it is often used in
MALDI-MS analysis. Thereby a few hundred nL of the dissolved sample and the dissolved
matrix are spotted on the target successively (sandwich method) or a mixture of both of
them. After evaporation of the solvent, instead of a homogenous area often a ring is formed
(“coffee ring). This can lead to a separation of the matrix and the polymer as well as between
polymers with different chain length. These effects have a huge impact on the results and
their reproducibility.
Methods
To measure the separation effects MALDI-MS Imaging in combination with a dried-droplet
sample preparation was used. In order to ensure a constant temperature the spotting and
evaporation process takes place in a self-made “climate chamber”.
The aim of our work is to identify the influence of different parameters on separation, as well
as the responsible forces in order to produce reliable MALDI-MS results.
Preliminary Data / Keynote or Plenary abstracts
First measurements show that at higher temperature the analyte molecules move towards
the outer rim of the droplet. This automatically leads to a thinner, but more concentrated
circular zone. Besides the temperature, the polymer structure, the solvent, and other physic-
chemical parameters (diffusion, capillary forces etc.) could have an impact on the separation
too. For example, for polyethylene glycol (PEG) recent publications [xx], which showed that
higher molecular PEG is located more on the outside, could be confirmed. In contrast to that,
our studies with PMMA showed opposite results. Also the solvent influences the quality of
the spectra. Whereas with THF (for PMMA) high quality spectra could be observed it was
different with toluene. Additionally, our results show that the way the sample is scanned has
a huge impact on the results.
Novel Aspect
It was the first time that MALDI-MS Imaging was used to analyze separation effects caused
by dried-droplet sample preparation.
Synthesis and structural Characterization of a
Theophylline:Nicotinamide Cocrystal
Franziska Fischer1,2, Lisa Tröbs1,2, Klaus Rademann2, and Franziska Emmerling1
1BAM Federal Institute for Materials Research and Testing, Berlin, Germany
2Department of Chemistry, Humboldt-University of Berlin, Berlin, Germany
Pharmaceutical cocrystals are compounds consisting of at least two different neutral
molecules, whereas one of it is an active pharmaceutical ingredient (API). The other
compound is called cocrystal former, typically a small organic molecule.[1]
Optimization of syntheses pathways and a thorough characterization of cocrystals
allow to tune the physicochemical properties like bioavailability or stability of the
APIs.[2]
Mechanochemical methods offer effective and environment-friendly syntheses of
cocrystals.[3] Since the cocrystals are obtained by mechanical grinding of solid
educts, the products are fine powders and their structure cannot be obtained from
single-crystal structural analysis. The structure can be solved from powder X-ray
data. [4]
A new theophylline cocrystal containing the cocrystal former nicotinamide is
presented. The material was synthesized via milling reactions and the crystal
structure was calculated from XRD data. Solid state NMR measurements gave
additional information about the cocrystal. Moreover, the crystallisation behavior of
the cocrystal theophylline:nicotinamide 1:1 was analyzed using an acoustic levitator.
Using this technical device the crystallization process was followed by time-resolved
synchrotron XRD measurements and simultaneously conducted Raman
spectroscopy.
[1] R. Thakuria, A. Delori, W. Jones, M. P. Lipert, L. Roy and N. Rodríguez-
Hornedo, Int. J. Pharm. 2013, 453, 101-125.
[2] A. Delori, T. Friscic und W. Jones, Crystengcomm 2012, 14, 2350–2362.
[3] Trask, A. V.; Jones, W. In Organic Solid State Reactions; Toda, F., Ed. 2005;
Vol. 254, p 41.
[4] S. Heiden, L. Tröbs, K.-J. Wenzel und F. Emmerling, CrystEngComm 2012, 14,
5128–5129.
A Ruler for the Nanoworld:
GISAXS on nanostructured surfaces.
Jan Wernecke, Victor Soltwisch, Frank Scholze, Michael Krumrey
Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin
When it comes to objects in the size scale of nanometres (10-9 m), length measurements are not that easy anymore. A suitable 'ruler' must possess a characteristic length shorter than the objects to be measured. Thus, the X-ray synchrotron radiation of the electron storage ring BESSY II with a wavelength below 1 nm is a very useful tool to measure nm-sized structures on and underneath surfaces, for example of organic solar cells, lithographic structures in semiconductors, or nanostructured polymer thin films. Grazing incidence small-angle X-ray scattering (GISAXS) is a very powerful tool to characterise the average shape, size, and spatial distribution of nano-objects in a non-destructive way.
The presented work gives an overview on how dimensional para-meters in the nanometre range can be measured with GISAXS and on the benefits of the technique. The unique setup and measurement ca-pabilities for GISAXS, especially at lower photon energies of 1.7 keV to 4 keV, at the four-crystal mono-chromator beamline of PTB at BESSY are outlined. The difficulties and challenges in obtaining reliable and accurate results in dimensional nanometrology are illustrated by a practical example of GISAXS mea-surements and data analysis on fabricated nm-sized line gratings. Examples of resonant small-angle scattering on the absorption edges of technologically relevant light elements like silicon or sulfur demonstrate the particular useful-ness of being able to record X-ray scattering patterns in a photon en-ergy range of 1.7 keV to 4 keV.
Further reading:
G. Renaud et al, Probing surface and interface morphology with Grazing Incidence Small Angle X-ray Scattering, Surf. Sci. Reports 64 (2009), 255-380
M. Krumrey et al, Synchrotron radiation-based X-ray reflection and scattering techniques for dimensional nanometrology, Meas. Sci. Technol. 22 (2011), 094032
J. Wernecke et al, Direct structural characterisation of line gratings with GISAXS, Rev. Sci. Instrum. 83 (2012), 10396
contact: [email protected] Adlershofer Forschungsforum | 12.11.2013
Fig. 1. GISAXS pattern of a line grating (schematic repre-
sentation in the top right corner) in parallel orien-
tation of synchrotron beam and grating lines (see
inset in top left corner). The image was recorded at a
photon energy of 3 keV at an incidence angle of 0.8°.
Flow Cytometry (FACS) for characterization and sorting of murine B cells to advance
development of monoclonal antibodies
Martin Dippong1, Sabine Flemig1, Katrin Hoffmann1, Jörg A. Schenk2, Rudolf J. Schneider1
and Maren Kuhne1
1 Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin
2 Hybrotec GmbH, Potsdam-Golm
Monoclonal antibodies (mabs) belong, due to their high affinity and selectivity, to the most
important tools in research, diagnostics and therapy. The production of mabs is performed via
hybridomas. The hybridoma technique, developed by Köhler and Milstein in the 1970s, is applied
nowadays mostly in the same way as 40 years ago. Antibody-producing B cells are fused with
“immortal” myeloma cells in order to obtain so-called hybridoma cells. The indispensable
identification and isolation of the desired antibody-producing hybridoma clone is yet not trivial. The
efficiency of PEG-stimulated fusion, respectively electrofusion, is very low and less than 1 % of the
fused cells survive. The subsequent immunoassay-based screening to identify a single hybridoma cell
line that produces an antibody with the desired selectivity is time-consuming and in the required
multiple rounds of limiting dilution to isolate the clones many of them are lost again. This makes the
process utterly risky, time-consuming as well as costly. The aim of our work is to optimize this
process. Our approach is to sort the B cells before fusion in a flow cytometer with sorting capability.
Among thousands of other B cells the ones that are able to produce the desired antibodies are
specifically double-labelled due to the fact that they carry the specific antibodies also on their outer
membranes. One label (an Alexa 647-labeled “secondary” antimouse IgG antibody, see Figure) elicits
the antibody-producing nature of the cell and a fluoresceinlabelled “target” molecule simultaneously
demonstrates the target-selectivity of the produced antibodies in a fluorescence-activated cell
sorting (FACS) process. The next step will be to use the isolated B cells for single-cell fusion with
myeloma cells in order to obtain the hybridoma cells which produce the desired antibodies. In our
immunisation trials we also pursue questions regarding immunisation strategies: which role plays
immunisation frequency and duration (and thus affinity maturation) for the fusion efficiency of B
cells? Is the degree of cell differentiation (obtained via CD “clusters of differentiation” marker
analysis) relevant for fusion? Is it less probable to achieve fusion with B cells that produce highaffinity
antibodies than with those of lower affinity? In this context we could show that enumeration of
different stages (plasma cells, pre B cells and ripe B cells) can be achieved by a combination of the
B220 and CD138 differentiation markers.
FITC Target Alexa
B-cell
FITC
Target Alexa 647
Biosynthese, Isolierung und Charakterisierung von Zearalenon-Konjugaten
A. Brodehl1, Berlin/D, A. Möller1, Berlin/D, H.-J. Kunte1, Berlin/D, M. Koch1, Berlin/D,
R. Maul1,2, Berlin/D
Antje Brodehl, Bundesanstalt für Materialforschung und –prüfung (BAM), Richard-Willstätter-Str. 11, 12489 Berlin/D
1Bundesanstalt für Materialforschung und –prüfung (BAM), Berlin/D; 2Leibniz Institut für
Gemüse- und Zierpflanzenbau Großbeeren/Erfurt e.V., Großbeeren/D Zearalenon (ZEN) ist ein Mykotoxin mit östrogener Aktivität, das von Schimmelpilzen der Gattung Fusarium gebildet wird [1]. Da häufig Getreide wie z. B. Mais, Weizen und Hafer von Fusarien befallen wird, sind insbesondere daraus gewonnene Lebens- und Futtermittel mit ZEN kontaminiert [2]. Die Kontamination beschränkt sich allerdings nicht nur auf das freie Mykotoxin, denn sowohl durch den Metabolismus der Pflanze [3] als auch durch den Pilzmetabolismus [4] können Glucose- und Sulfat-Konjugate gebildet werden. Diese sogenannten „maskierten“ Mykotoxine entgehen aufgrund ihrer geänderten chemischen Struktur der Routineanalytik. Die Bestimmung von „maskierten“ Mykotoxinen stellt die Lebensmittelanalytik jedoch vor große Herausforderungen, da Standardsubstanzen bislang nicht kommerziell erhältlich sind. Mit dem Ziel der Biosynthese von ZEN-Konjugaten wurde daher die mikrobielle Umwandlung von ZEN durch verschiedene ZEN-metabolisierende Pilzspezies (Aspergillus oryzae und Rhizopus sp.) [4,5] untersucht. Hierfür wurde die jeweilige Metabolitbildung und –verteilung nach ZEN-Zugabe zur Pilzkultur von unterschiedlichen Pilzstämmen ermittelt. Die qualitative Analyse der gebildeten ZEN-Konjugate erfolgte unter Verwendung der HPLC-MS/MS, indem die zu erwartenden Massenübergänge möglicher Metabolite im SRM-Modus aufgezeichnet wurden. Das Konjugat ZEN-Sulfat erwies sich bei den vorangegangenen Untersuchungen als aussichtsreich, da einige der eingesetzten Pilzstämme ZEN dahingehend umsetzen. Ein weiterer Schwerpunkt war daher die Entwicklung einer Cleanup-Strategie für die Isolierung von ZEN-Sulfat aus dem Flüssignährmedium. Im Rahmen der durchgeführten Untersuchungen konnte gezeigt werden, dass alle untersuchten Rhizopus-Stämme, sowie Aspergillus oryzae, in der Lage sind, ZEN zu verschiedenen Konjugaten (ZEN-Sulfat, ZEN-Glucosid) zu metabolisieren, wobei deutliche Unterschiede in der Metabolitverteilung selbst bei eng verwandten Stämmen beobachtet werden konnten. Weiterhin wurde die präparative Gewinnung für das Konjugat ZEN-Sulfat erfolgreich etabliert. Auf Grundlage der Ergebnisse sollen weitere Studien zur Optimierung der Biosynthese sowie der Aufreinigungsstrategie durchgeführt werden. [1] J. Plasencia et al., Appl. Environ. Microb. 1991, 57, 146-150.; [2] F. Berthiller et al., Mol. Nutr. Food Res. 2013, 57, 165-186.; [3] G. Engelhardt et al., Adv. Food Sci. 1999, 21, 71-78.; [4] H. Kamimura, Appl. Environ. Microb. 1986, 52, 515-519.; [5] S. H. Elsharkawy et al., Appl. Environ. Microb. 1991, 57, 549-552.
Solar-blind AlGaN MSM photodetectors on planar and ELO AlN/sapphire templates
M. Brendel, A. Knigge, F. Brunner, S. Einfeldt, A. Knauer, V. Kueller, U. Zeimer, M. Weyers
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik
Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany, Email: [email protected]
Abstract
Semiconductor photodetectors (PDs) with a cut-off wavelength cut-off in the ultra-violet (UV) spectral region are
required for various applications, e.g. to control UV lamps, UV LEDs and excimer lasers in research, disinfection
and medical applications. Since the cut-off directly correlates to the absorption edge of the semiconductor,
the AlxGa1-xN material system is perfectly suited to tune cut-off between about 365 nm and 200 nm via the Al mole
fraction x. Thus, solar-blindness, i.e. photodetection only below 280 nm, can be achieved with x > 0.4 in the
absorption layer material. Metal-semiconductor-metal photodetectors (MSM PDs) have a relatively simple
epitaxial layout and can be processed with short cycle times due to the planar arrangement of interdigitated
Schottky contacts. However, the quantum efficiency (QE) of optoelectronic devices is generally strongly affected
by material perfection, mainly because a high threading dislocation density (TDD) raises carrier recombination.
In this work, metalorganic vapor phase epitaxy has been used to manufacture planar as well as epitaxial laterally
overgrown (ELO) AlN/sapphire templates with different TDD serving as substrates for further epitaxy of
Al0.4Ga0.6GaN absorber layers [1]. Solar-blind Al0.4Ga0.6GaN MSM PDs on the ELO AlN/sapphire template show
anisotropic device characteristics depending on the orientation of the electrodes with respect to the orientation of
the underlying stripe-pattern which is used to create the ELO AlN/sapphire template (see Fig. 1). For devices with
electrodes perpendicular to those stripes (ELO) a quantum efficiency of QE ~ 140 was found for 20 V bias at
room-temperature. This photoconductive gain is explained by carrier transport along channels with increased Ga
content resulting from faceted growth at the steps of the ELO template (see Fig. 2). The resulting potential barrier
is confirmed by the deactivation energy found for the temperature dependence of the QE (see Fig. 3). In contrast,
photodetectors with electrodes running parallel (ELO║) to these Ga-rich channels do not show gain but have an
enhanced QE at elevated bias voltage compared to devices on planar AlN templates (see Fig.1). This effect is
attributed to different TDD in the absorber layers. A model explaining the anisotropy of carrier transport in MSM
PDs on ELO AlN/sapphire templates is proposed.
Figures
1
2
3
Fig. 1 Responsivity versus applied bias for a planar device (black dashed line) as well as for an ELO PD (black solid line)
and an ELO|| PD (black dotted line) – the inset images show the electrode orientation of the ELO and the ELO|| devices
Fig. 2 Cross-sectional SEM and monochromatic CL images of the Al0.4Ga0.6N absorber layer grown on ELO template showing
a periodic spatial modulation of luminescence (recorded at 100 K, 10 kV and 1.8 nA) – in the SEM image triangles and a
dashed zig-zag line indicate the modulation also seen by the image contrast
Fig. 3 The Arrhenius-plot of the temperature dependence of the QE at 20 V bias shows thermal quenching of the QE with
slopes E of 0.05 eV for the planar and 0.34 eV, for the ELO PD – the expected trend for electron Hall-mobility in nid
GaN (room-temperature value from [2] normalized to corresponding QE) of the planar PD (stars) matches the
experimental trend of the QE data.
References
[1] A. Knigge et al., Jpn. J. Appl. Phys. 52, 08JF03 (2013) [2] M. Ilegems, H.C. Montgomery, J. Phys. Chem. Solids 34, 885 (1972)
0 5 10 15 20
10-7
10-5
10-3
10-1
101
ELO
dfinger
= 5 µm
~ 260 nm
ELO planar
ELO||
responsiv
ity (
A/W
)
voltage (V)
ELO
5 µm
EQE = 1
2.2 2.4 2.6 2.8 3.0 3.2 3.4
0.01
0.1
1
10 Trend expected due to Hall-mobility (nid GaN)
planar
ELO
quantu
m e
ffic
iency @
260 n
m,
20 V
1000 / T (K-1)
dfinger
= 15 µm
422 K 363 K 305 K
E ~ 0.34 eV
E ~ 0.05 eV
CL (monochromatic)
271nm
292nm
262nm
SEM (cleaved edge)
Al0.4
Ga0.6
N 1 µm
Ga rich
Analyse von Kunststoffadditiven
F. Börno1, D. Deiting
2, N. Jakubowski
1 ,M. Kreyenschmidt
2, U. Panne
1,3
1) BAM Bundesanstalt für Materialforschung und -prüfung, Fachbereich 1.1 Anorganische
Spurenanalytik, Richard-Willstätter-Str. 11, 12489 Berlin, Deutschland
2) Fachhochschule Münster, Fachbereich Chemieingenieurwesen, Stegerwaldstr. 39, 48565 Steinfurt,
Deutschland
3) Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Str. 2, 12489 Berlin,
Deutschland
Kunststoffe sind ein wichtiger Bestandteil unseres alltäglichen Lebens. Durch die Zugabe von
speziellen anorganischen und organischen Verbindungen können die Eigenschaften von Kunststoffen
beeinflusst werden. Diese sogenannten Additive können jedoch auch eine gesundheitliche Gefahr
darstellen und sind deshalb gesetzlich reguliert.
Ziel unserer Arbeit ist die Entwicklung einer leistungsfähigen Multielementanalytik für verschiedene
Kunststoffmatrices.
Mittels ETV-ICP-OES, LA-ICP-MS und ICP-MS nach Mikrowellenhochdruckaufschluss wurden
Kunststoffproben auf ihre Additivzusammensetzung hin untersucht. Als Probenmaterial dienten
LDPE- und ABS-Kunststoffe, welche nach industriell üblichen Verfahren mittels Knetkammer und
Schneckenextruder hergestellt wurden. In diese Proben wurden Br, Cd, Cu, Cr, Fe, Sb enthaltende
Additive in rein organischer, rein anorganischer und gemischter Form eingearbeitet.
Die direkten Feststoffverfahren ETV-ICP-OES und LA-ICP-MS bieten den Vorteil einer wenig
aufwendigen Probenvorbereitung und minimierten Kontaminationsanfälligkeit. Die Kalibrierung
dieser Verfahren ist jedoch meist nur mit matrixangepassten Standards möglich. Der
Probenaufschluss mittels Mikrowelle und anschließender Bestimmung mittels ICP-MS ermöglicht
eine einfache Kalibrierung über flüssige Standards ist jedoch sehr zeitintensiv und in einem höheren
Maße kontaminationsanfällig. Von den verwendeten Verfahren ermöglicht nur die LA-ICP-MS eine
quantitative Bestimmung des Bromgehaltes, wobei die LA-ICP-MS eine sehr starke
Matrixabhängigkeit aufweist, da verschiedene Kunststoffe sehr unterschiedlich mit der
Laserstrahlung wechselwirken[1]
. Das oft als interner Standard verwendete Kohlenstoffisotop 13
C
reicht dabei nicht aus, um diese Unterschiede zu korrigieren[2]
.
Die hier vorgestellten Analyseverfahren bieten in der Kunststoffcharakterisierung für eine Vielzahl an
Problemstellungen Lösungsansätze. Ihre Vor- und Nachteile werden in dieser Arbeit
gegenübergestellt.
Referenzen [1] C. Simons, Polymer basierte Materialien zur matrixangepassten Kalibrierung der Massenspektrometrie mit
induktiv gekoppeltem Plasma nach Laserablation. Thesis, Institut für anorganische und angewandte Chemie,
Universität Hamburg, 2009
[2] D. A. Frick, D. Günther, Fundamental studies on the ablation behaviour of carbon in LA-ICP-MS with respect
to the suitability as internal standard, Journal of Analytical Atomic Spectrometry, 2012, 27, 1294-1303
Quantitative Analyse der Silbernanopartikelaufnahme durch Zellen mittels LA-ICP-MS
Frank S. BIERKANDT1, Philipp REICHARDT2, Andrea HAASE2, Harald JUNGNICKEL2, Jutta
TENTSCHERT2, Andreas LUCH2, Norbert JAKUBOWSKI1
1BAM Bundesanstalt für Materialforschung und – prüfung, FB 1.1 Anorganische Spurenanalytik, Berlin
2BfR Bundesinstitut für Risikobewertung, Sicherheit von verbrauchernahen Produkten, Berlin
Silbernanopartikel und an Nanopartikeln gebundenes Silber werden auf Grund ihrer
antibakteriellen Eigenschaften in zunehmenden Umfang in Verbraucherprodukten, von Kosmetika
über Kleidung bis hin zu Verpackungen, eingesetzt. Da gleichzeitig die toxikologischen Eigenschaften
der Nanopartikel noch nicht vollständig erforscht sind, ist die Aufklärung der Wirkung und der
vorrausgehenden Aufnahme der Nanopartikel in Zellen für eine Risikoeinschätzung unerlässlich.
Laserablation (LA) in Verbindung mit der induktiv-gekoppelten Massenspektrometrie (ICP-MS)
ist eine effiziente Methode, die für die Analyse von metallhaltigen Biomolekülen, besonders
Proteinen, aber auch größeren biologischen und geologischen Strukturen etabliert ist [1,2]. Neben
einem großen dynamischen Bereich und einer niedrigen Nachweisgrenze eignet sich diese
Kombination auf Grund der einfache Probenvorbereitung und des geringes Probenvolumens sehr gut
für die Untersuchung inkubierter Zellen [3,4]. Des Weiteren könnte LA-ICP-MS durch Immunoassays
mit metallmarkierten Antikörpern auch für die Untersuchung der Proteomveränderungen durch die
Nanopartikelaufnahme genutzt werden [5].
Deshalb wurde ein Modellsystem bestehend aus zwei Zelllinien (A549 und THP1) nach der
Inkubation mit verschiedenen Konzentrationen von Silbernanopartikeln mittels LA-ICP-MS
analysiert.
Die behandelten Zellen wurden lysiert und definierte Lysattropfen auf Objektträgern getrocknet.
Um die Stabilität der Messbedingungen zu kontrollieren und auftretende Schwankungen zu
korrigieren, wurde Lutetium als interner Standard den Lysaten hinzugefügt und so die
Vergleichbarkeit unterschiedlicher Messungen gewährleistet. Durch die Ablation des betreffenden
Bereichs des Objektträges durch parallele Linienscans und Detektion des Aerosols im ICP-MS konnte
mit Hilfe der integrierten ICP-MS-Signale jedes Spots die Aufnahme der Silbernanopartikel durch die
Zellen quantitativ untersucht werden. Die Ergebnisse zeigen, dass sich Rate und Menge der
aufgenommen Nanopartikel bezogen auf eine steigende Konzentration in der Inkubationslösung
deutlich für alle hier untersuchten Kombinationen Silbernanopartikel-Zelle unterscheiden.
LA-ICP-MS konnte erfolgreich für das Imaging und die quantitative Analyse der Aufnahme
anorganischer Nanopartikel in Zellen eingesetzt werden, um so die Untersuchung der einhergehenden
Veränderungen in Abhängigkeit der aufgenommenen Nanopartikel zu ermöglichen.
[1] J. S. Becker International Journal of Mass Spectrometry 289 (2010) 2-3, 65.
[2] E. Moreno-Gordaliza, C. Giesen, A. Lázaro, D. Esteban-Fernández, B. Humanes, B. Cañas, U. Panne, A.
Tejedor , N. Jakubowski, M. M. Gómez-Gómez, Analytical Chemistry 83 (2011) 20, 7933.
[3] R.E. Russo, X. Mao, H. Liu, J. Gonzalez, S.S. Mao, Laser ablation in analytical chemistry - a review, Talanta 57
(2002).
[4] M. B. Fricker, D. Kutscher, B. Aeschlimann, J. Frommer, R. Dietiker, J. Bettmer, D. Günther, International
Journal of Mass Spectrometry 307 (2011) 1-3, 39.
[5] C. Giesen, L. Waentig, U. Panne, N. Jakubowski, Spectrochimica Acta - Part B Atomic Spectroscopy 76 (2012) 27.
Chemische Analytik von Solarsilicium Matthias Balski, Jens Pfeifer, Heinrich Kipphardt, Ulrich Panne BAM Bundesanstalt für Materialforschung und –prüfung, Richard-Willstätter-Straße 11, 12489 Berlin Fremdelement-Verunreinigungen in Silicium können schon im Spurenbereich den Wir-
kungsgrad von Solarzellen deutlich herabsetzen. Die Herstellung neuer siliciumbasier-
ter Solarzellenmaterialien mit verbesserten photovoltaischen Eigenschaften stellt daher
hohe Anforderungen bezüglich der Kenntnis der chemischen Zusammensetzung des
Rohmaterials und der Zwischenprodukte im Fertigungsprozess.
Im Rahmen der spezifischen Materialforschung innerhalb des Spitzenclusters Solarval-
ley Mitteldeutschland ist es ein Ziel, die Bestimmung von Spurenverunreinigungen in
Solarsilicium industrieorientiert zu verbessern. Dafür wurde ein Spektrum zuverlässiger
Verfahren erarbeitet, welche zum einen auf unterschiedlichste Silicium-Materialien mit
variablem Verunreinigungsgehalt ohne Verluste an Präzision anwendbar sind und zum
anderen die Erfassung möglichst vieler Analyte in einem Analysegang ermöglichen.
Wir stellen ein leistungsstarkes Analyseverfahren vor, welches auf der Massenspekt-
rometrie mit induktiv gekoppeltem Plasma (ICP-MS) als universeller Referenzmethode
basiert. Nach Anreicherung der Analyte durch Matrixabtrennung können in einem Ana-
lysengang 29 Elemente mit einem Arbeitsbereich über sechs Größenordnungen und
Nachweisgrenzen bis zu 40 pg·g-1 im Feststoff bestimmt werden.
Dieses Referenzverfahren wurde zur Entwicklung einer schnellen, direkten, auf der
Glimmentladungs-Massenspektrometrie (GDMS) basierenden Feststoffmethode ver-
wendet. Durch parallele Messungen von Silicium-Proben aus der Solarindustrie mit
ICP-MS und GDMS konnte erstmalig eine Kalibration der GDMS für B, P, As, Ga, Ge
und Fe an realen Industrieproben erreicht werden.
A Ruler for the Nanoworld: SAXS on nanoparticle suspensions
Christian Gollwitzer*, Raul García-Diez, Michael Krumrey
Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin
Accurate length measurements are difficult for objects in the nanometre size range with typical dimensions between 1 nm and 100 nm. A suitable 'ruler' is needed with a characteristic length comparable to the object to be measured. Small-angle X-ray scattering (SAXS) using X-ray synchrotron radiation with a wavelength below 1 nm is well suited to determine the size and size distribution of nanoparticles in suspension.
SAXS at the four-crystal mono-chromator beamline of PTB at BESSY is used in a number of projects in the frame of the European Metrology Research Programme (EMRP) due to the unique ability of the beamline to measure at photon energies down to 1.75 keV. This energy range covers the absorption edges of biologically relevant elements like phosphorus, sulfur, potassium and calcium, which makes it possible to get structural information about the distribution of these elements using anomalous scattering (ASAXS). Typical samples examined at PTB include nanoparticles in biological media, exosomes and micro-particles expelled from living cells and isolated from body fluids, functionalized nanoparticles used as a biomolecular probe, as well as reference particles for other sizing techniques.
Further reading:
M Krumrey et al., Synchrotron radiation-based X-ray reflection and scattering techniques for dimensional nanometrology, Meas. Sci. Technol. 22 (2011), 094032
G Gleber et al., Traceable size determination of PMMA nanoparticles based on Small Angle X-ray scattering, J. Phys.: Conf. Ser. 247 (2010), 012027
* contact: [email protected] Adlershofer Forschungsforum | 12.11.2013
SAXS curve recorded for a concentrated sample of microvesicles derived from erythrocyte cells. The measured curve can be fitted by a combination of core-shell particles representing the vesicles and a contribution from the embedding protein. The curve was stitched together from a recording at a photon energy of 4 keV and a second image at 10 keV.
Green-IT - Flexible and Efficient Microwave Power Amplifiers for
Next-Generation Mobile Communication Infrastructure
Highly efficient and multifunctional amplifiers, which are developed at FBH, ensure that - especially
thanks to the increasing digitization - mobile applications are becoming increasingly powerful and
new wireless standards like LTE and WiMAX are possible at all.
Amplifiers are key components in all electronic devices. In cellular base stations power amplifiers
ensure that the necessary power is provided for radiating the data. But they are also largely
responsible for the energy consumption. Moreover, the previous (analog) concepts are frequency
dependent, that is, they only use one signal frequency and are limited in their efficiency as they are
optimized for maximum output power.
The novelty of the FBH power amplifiers is that they are digital up to the output of the final stage.
The DC power consumption due to analog signal processing is significantly reduced which is in line
with the commitment for a green IT . This lowers the costs and simplifies system architecture.
Moreover, the digital PA concept provides flexible frequency usage (multi-band), can handle large
signal bandwidths and shows potentially high overall efficiencies of up to 100%, independently of the
power back-off.
Kontakt:
Dr.-Ing. Andreas Wentzel
Business Area Microwave Components & Systems
Ferdinand-Braun-Institut
Leibniz-Institut für Hoechstfrequenztechnik
Gustav-Kirchhoff-Straße 4
D-12489 Berlin / Germany
phone: +49 (0)30 6392-2627
fax: +49 (0)30 6392-2642
e-mail: [email protected]
www.fbh-berlin.de
Synchrotron based analysis of the Cu(In,Ga)Se2/CdS and Cu(In,Ga)Se2/ZnS interfaces
using soft x-ray photoemission spectroscopy (SXPS) and near edge x-ray absorption fine
structure spectroscopy (NEXAFS).
B. Ümsür1*, W. Calvet1, B. Höpfner1, A. Steigert1, I. Lauermann1* and M. Ch. Lux-Steiner1,2
1 Helmholtz-Zentrum-Berlin, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
2 Freie Universität Berlin, Department of Physics, Arnimallee 14, D-14195 Berlin, Germany
Thin film solar cells based on the chalcopyrite absorber material Cu(In,Ga)Se2 have the
highest potential to reduce fabrication costs in photovoltaics since material consumption and
requirements in production are low. Until now, efficiencies above 20% (lab-scale) and above
15% (fabrication-scale) have been obtained for single junction devices, starting to compete
with silicon-based devices. It is assumed that besides defects in the bulk material, the
interface between the absorber and buffer layer mainly based on CdS plays an important role
with respect to band alignment and appearance of interface states causing recombination in
this region. One research aim is to replace CdS by a less toxic alternative such as ZnS. A
second point that has to be considered is inter-diffusion. Especially, the diffusion of Cd into
the chalcopyrite absorber with its impact on PV cell performance is not clarified yet. In order
to study this more in detail, synchrotron radiation based techniques such as SXPS and
NEXAFS with a tunable light source are well suited. In this work we have investigated
Cu(In,Ga)Se2 absorbers covered by thin layers of CdS and ZnS by means of chemical bath
deposition (CBD). In a second step, the samples have been annealed under ambient conditions
up to 200 °C to study possible changes induced by inter-diffusion. To get a closer insight into
the relevant interface region, the ZnS or CdS films have been removed by a short etching step
in diluted HCl prior to the investigation with synchrotron light.
*Contact email:
Crystal Structures and Dissolution Behavior of
Carbamazepine Cocrystals
Lisa Tröbs1, Nicolai Zientek1, Michael Maiwald1, and Franziska Emmerling1
1BAM Federal Institute for Materials Research and Testing, Berlin, Germany
Over the last years, the number of publications outlining the advances in design
strategies, growing techniques, and characterization of cocrystals increased
significantly. Cocrystals are compounds consisting of at least two different neutral
molecules, whereupon pharmaceutical cocrystals are composed of an active
pharmaceutical ingredient (API) and a cocrystal former, typically a small organic
molecule. Optimization of synthesis pathways and a thorough characterization of
cocrystals allow to tune the APIs physicochemical properties like solubility,
bioavailability or stability.[1,2] Although solvothermal synthesis of cocrystals is the
predominant method, the mechanochemical synthesis has also been applied
successfully.[3,4]
Herein, we report on the mechanochemical synthesis of new pharmaceutical
cocrystals based on the API carbamazepine. The crystal structures were solved from
powder X-ray data. To analyze the dissolution behavior of these cocrystals an online-
NMR device waiving deuterated solvents was employed. Using this technique, the
cocrystals were pressed into tablets and dissolved in a stirred cell under ambient
temperatures in a solvent that simulates stomach acid.
[1] D. R. Weyna, T. Shattock, P. Vishweshwar and M. J. Zaworotko, Cryst. Growth Des.
2009, 9, 1106-1123.
[2] A. Delori, T. Friscic and W. Jones, CrystEngComm 2012, 14, 2350-2362.
[3] M. Klimakow, P. Klobes, A. F. Thünemann, K. Rademann and F. Emmerling, Chem.
Mater. 2010, 22, 5216-5221.
[4] S. Heiden, L. Tröbs, K.-J. Wenzel and F. Emmerling, CrystEngComm 2012, 14, 5128-
5129.
Investigations of Degradation of Cementitious Materials
by in-situ Structure Analysis
Stroh, J., Berlin/DE, Emmerling, F., Berlin/DE
Julia Stroh, BAM Federal Institute for Materials Research and Testing,
Richard-Willstätter-Straße 11, 12489 Berlin
The cement durability and degradation of buildings due to influence of aggressive environments is a subject of numerous investigations [1-4]. A recent tendency is to build more challenging cement and concrete constructions, also contacting aggressive environments such as sea water or sulfate solutions. Furthermore, progressive cement corrosion affects the durability of existing concrete constructions. Only a profound knowledge about the interaction mechanisms of cement bulk phases with different aggressive agents enables the development of more resistant binders. Thus, the service life period of concrete constructions is enhanced.
The objective of our investigation is to unravel the mechanism of cement deterioration due to sulfate attack for different salt concentrations and exposure times. Synchrotron X-ray Diffraction (SyXRD) analysis of thin sections of cement samples after exposure to sulfate attack were carried out (Figure 1) using a beam size of 10 µm to provide high spatial resolution. Based on the results a function sulfate attack progress vs. concentration of sulfate solution or exposure time can be fitted. The extrapolation to the low sulfate concentrations and furthermore the prediction of service life of the cement construction will be available.
Figure 1 Scheme of the experimental setup and data processing
Literature:
[1] J. J. Valenza II, G. W. Scherer, Cem. Concr. Res. 2007, 37, 1007-1034. [2] F. P. Glasser, J. Marchand, E. Samson, Cem. Concr. Res. 2008, 38, 226-246. [3] M. Schlegel, U. Müller, U. Panne, F. Emmerling, Anal. Chem. 2011, 83, 3744-3749.[4] M. Santhanam, M. D. Cohen, J. Olek, Cem. Concr. Res. 2002, 31, 845-851.