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Instrumentation: Transmission Electron Microscopy
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Knoll and Ruska (1932)
the first Transmission Electron Microscope
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Contents:
1. Introduction
2. Sources
3. Lenses
4. Spectrometers and Filters
5. STEM
6. Advanced Instrumentation
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light source
illumination system
imaging system
specimen
Basic functions of an optical microscopeH.J. Penkalla
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Imagingsystem
specimen
Arrangement of the main components at the TEM
illuminationsystem
light (electron)source
H.J. Penkalla
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Electron Beam Sources: Thermal Emitter
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Electron Beam Sources: Field-Emitter
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Lens Aberrations:
Spherical and Chromatic Aberration
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Specimen preparation: ion beam thinning
2.5 - 4.0 kV
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Specimen preparation: electroytical jet thinning
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Specimen preparation: ultramicrotomy
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Specimen preparation: carbon replica
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Gate-width 12,5 nm
A new era in nanoanalysis:
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Design of a Focused Ion Beam Workstation FIB
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FIB-nanolithography :FIM/TAP - Tips
Nanodevices
Magnetic memory
Test-masks
for EUV-
microscopy
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FIB Preparation of TEM lamellae
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Contrast enhancement by the use of the objectiveaperture
H.J. Penk
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Structure Chemistry
Bonding
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High Resolution Transmission Electron Microscopy
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plane wave
Transmissionfunction
Fourier-Transformation
Fourier-Transformation
Diffractionpattern
real image
HRTEM
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HRTEM:
Nb/Sapphire
Interfaces
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Contrast Transfer: Incoherent Imaging System
Rayleigh Criterion
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Specimenphase shift of scattered wave: -π/2
phase shift by defocus: -π/2
Intensity contrast
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Spherical Aberration
MagneticLens
GaussianImage Plane
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Contrast Transfer Function (CTF)
Scherzer Focus, no damping
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Contrast Transfer:
Real Imaging System
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Spherical Aberration
MagneticLens
GaussianImage Plane
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Lens
P
CS = 0
Image plane
Aberration corrected electron optics
TU DarmstadtEMBL HeidelbergForschungszentrum Jülich
Volkswagen Stiftung
Haider, Rose, Urban et al. Nature 392, 768 (1998)
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Hexapole Cs-Corrector
(Rose, Haider)
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Example: SrTiO3, calculated images
Structuremodel
withoutcorrector
Cs-corrector,Cs = + 40 µm
Cs-corrector, Cs = - 40 µm, changes in oxygen sublattice
Jia, Lentzen, Urban, Science 299 (2003)
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Twin Boundaries inBaTiO3
Jia and Urban, Science 303 (2004)
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CsxNb2.54W2.46O14
Focal-series reconstruction of the object exit-plane wave function
Phase image = projected potential for thin object
Th. Weirich
J. Barthel, A. Thust (ER-C)
G. Cox, H. Hibst(BASF)
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aa
bb
averaged phase image+ p2gg symmetry correction
projected crystal structure
CsxNb2.54W2.46O14
Th. Weirich, J. Barthel, A. Thust (ER-C), G. Cox, H. Hibst (BASF)
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Structure Chemistry
Bonding
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Analytical TEM: Electron Intensity Distribution
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Inelastic Scattering, low energy losses:
phonon and plasmon excitation
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h ν
( 2 ) E k i n
( 1 ) E 0 - Δ E ,
D
= E B + E k i n
E 0
E Δ
Inelastic Scattering: Analytical Information
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Schematical Energy Loss Spectrum
h ν
( 2 ) E k i n
( 1 ) E 0 - Δ E ,
D
= E B + E k i n
E 0
E Δ
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B
Energy Loss Spectrometer(magnetic prism)
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The Omega Energy Filter
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CondensorSystem(KöhlerIllumination)AnalyticalObjective Lens
First ProjectorSystem
Imaging½-Spectrometer
SecondProjectorSystem
ViewingChamber
ElectronDetectorand Camera
Energy SelectingSlit
EucentricGoniometer
Cathode
Energy Filter
Specimen
ImagingΩ−Spectrometer
Energy selectingslit
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The Gatan Imaging Filter
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Elemental Distribution Images:
Three Window Technique