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Calibration system with an indirect photoelectric chargerfor legislated vehicle number emission measurement counters

in the single counting mode

B. Grob, J.-C. Wolf, B. Kiwull, R. Niessner n

Institute of Hydrochemistry, Chair for Analytical Chemistry, Technische Universitt Mnchen, 81377 Munich, Germany

a r t i c l e i n f o

Article history:

Received 28 August 2013

Received in revised form

12 December 2013

Accepted 3 January 2014Available online 13 January 2014

Keywords:

Indirect photoelectric charger

CPC

GFG

CAST

Counting efficiency

Unipolar charger

a b s t r a c t

A calibration setup has been established to calibrate or validate UN-ECE Regulation 83

compliant CPCs. A spark discharge generator (GFG 1000) is used to produce carbon

particles. For charge conditioning an indirect photoelectric charger is combined with an

electrostatic precipitator instead of the very common radioactive bipolar charger. The

particle number concentration is determined with a Faraday cup electrometer. Detailed

studies have been conducted to validate the calibration setup. The particle size classifica-

tion was checked by a screen-type diffusion battery. Moreover the effect of multiple

charged particles was investigated. Three independent measurements of the counting

efficiency as well as the linearity of a typical regulation compliant counter were

performed. The calibration setup was also compared with a similar system using a

radioactive bipolar charger. The obtained results demonstrate that the counting efficiency

can be measured in a particle size range from 13 nm to 60 nm with a high repeatability.

A linearity check at a particle size of 55 nm is possible in a concentration range of

100010 000 cm3. The effect of multiple charged particles produced by the indirect

photoelectric charger was found to be negligible. Additionally, the difference between a

CAST aerosol and a GFG aerosol as a calibration material is discussed.

& 2014 Elsevier Ltd. All rights reserved.

1. Introduction

The measurement of non-volatile particle number concentration emitted by light or heavy duty vehicles has received

much attention in the last years due to the introduction of UN-ECE Regulations 83 and 49, respectively (Giechaskiel &

Bergmann, 2011;Giechaskiel et al., 2008a,2008b). On account of the legislation, the commercially available systems consist

of a heated diluter and an evaporation tube combined with a dilution at ambient temperature for removal of the volatiles

and semi-volatile components in the aerosol (Giechaskiel et al., 2010;Wei et al., 2006). The remaining non-volatile particles

larger than 23 nm are counted by a condensation particle counter (CPC). Therefore the legislation dictates counting

efficiencies for the CPCs at 23 nm and 41 nm of 50712% and 490%, respectively. The efficiency can be determined either

by comparing the counter with an electrometer or another CPC (calibrated with an electrometer). In addition, the linear

response of the counter in the concentration range from 1 cm3 to the upper threshold of the single particle count mode

Contents lists available atScienceDirect

journal homepage: www.elsevier.com/locate/jaerosci

Journal of Aerosol Science

0021-8502/$ - see front matter & 2014 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.jaerosci.2014.01.001

n Corresponding author.

E-mail addresses: [email protected](B. Grob),[email protected](R. Niessner).

URL: http://www.ws.chemie.tu-muenchen.de(R. Niessner).

Journal of Aerosol Science 70 (2014) 5058
http://www.sciencedirect.com/science/journal/00218502http://www.elsevier.com/locate/jaeroscihttp://dx.doi.org/10.1016/j.jaerosci.2014.01.001mailto:[email protected]:[email protected]:http://www.ws.chemie.tu-muenchen.dehttp://dx.doi.org/10.1016/j.jaerosci.2014.01.001http://dx.doi.org/10.1016/j.jaerosci.2014.01.001http://dx.doi.org/10.1016/j.jaerosci.2014.01.001http://dx.doi.org/10.1016/j.jaerosci.2014.01.001mailto:http://www.ws.chemie.tu-muenchen.demailto:[email protected]:[email protected]://crossmark.crossref.org/dialog/?doi=10.1016/j.jaerosci.2014.01.001&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1016/j.jaerosci.2014.01.001&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1016/j.jaerosci.2014.01.001&domain=pdfhttp://dx.doi.org/10.1016/j.jaerosci.2014.01.001http://dx.doi.org/10.1016/j.jaerosci.2014.01.001http://dx.doi.org/10.1016/j.jaerosci.2014.01.001http://www.elsevier.com/locate/jaeroscihttp://www.sciencedirect.com/science/journal/00218502

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has to be checked. The slope has to be 1 70.1. In the case of an electrometer as reference the linearity is checked above

1000 cm3 due to the high signal-to-noise ratio of the amplifier for very low concentrations.

Due to the fact that a decrease in counting efficiency up to 20% within 1.5 years of measuring exhaust has been observed

for CPCs (Giechaskiel & Bergmann, 2011), a periodical check of the calibration is absolutely necessary. So far, the most

common method to calibrate a CPC is to use a diluted test aerosol, which gets neutralized by a bipolar charger containing a

radioactive source. A monodisperse aerosol is produced by a differential mobility analyzer (DMA) followed by a second

diluter. As long as the fraction of multiple charged particles is low the charge number concentration of the monodisperse

aerosol can be measured and the counting efficiency of a parallel connected CPC obtained (Giechaskiel et al., 2009;Wanget al., 2010;Wiedensohler et al., 1997).

However, in the legislation there is no calibration material specified, even though it is known that the counting efficiency

of a CPC depends strongly on the chemical composition and morphology of the particles (Giechaskiel et al., 2011;Helsper&

Niessner, 1985;Mamakos et al., 2013;Sem, 2002;Wang et al., 2010). So far it is only recommended in the legislation to use

emery oil (undefined mixture of poly--olefins) or flame soot particles produced by a Combustion Aerosol Standard (CAST).

Nevertheless the counting efficiency of emery oil seems to be significantly higher than for particles generated by the CAST

within the relevant size range (2341 nm) as shown byWang et al. (2010) and Giechaskiel& Bergmann (2011). For diesel

engine exhaust particles a difference between about 7% and 9% in the total number concentration was observed for two

CPCs calibrated with emery oil and a CAST, respectively (Wang et al., 2010). Moreover, a combustion flame generated aerosol

always contains an amount of volatile polycyclic aromatic hydrocarbons which are also present on the particle surface due

to condensation. The composition is affected by the physical properties (vapor pressure) as well as by the chemical

composition of the fuel and the mixing gases and therefore it is very difficult to guarantee a repeatable production of

particles with the same composition and morphology.Because of all these obvious problems a calibration standard is necessary which is standardized and has a repeatable

composition, surface property, and morphology of the produced aerosol particles. An alternative to the CAST can be a spark

discharge generator to produce a carbon aerosol. With such a generator it is possible to generate an aerosol of predictable

characteristics as it contains pure carbon particles and an inert gas as the carrier gas (mostly argon) (Evans et al., 2003;

Helsper et al., 1993). Furthermore a calibration system containing no radioactive source for charge conditioning would be an

extreme advantage due to legislation issues.

In this study we present a calibration setup for legislation compliant CPCs, containing a spark discharge generator

equipped with analytically ultrapure graphite electrodes. For charge conditioning a newly developed indirect photoelectric

unipolar charger (Grob et al., 2013) is used instead of a radioactive bipolar charger. The charger allows very soft ion

production without any ozone formation. This is important, as ozone would immediately produce easily wettable particle

surfaces, which are prone to lower needed supersaturation within a CPC (Kotzick et al., 1997). To avoid a high fraction of

multiple charged particles coming from the spark discharge generator an electrostatic precipitator is placed in front of the

indirect photoelectric charger. Analogous to the described method above, the aerosol is separated by an electrostaticclassifier, and a Faraday cup electrometer is used as the reference counter. The system is validated by a reference CPC (for

particle concentration) and a diffusion battery (for particle size). The purpose of this study is to demonstrate that the effect

of multiple charged particles produced by the unipolar charger is negligible and it is possible to calibrate a legislation

compliant counter. Moreover the results are compared with measurements done with a CAST-generated aerosol.

2. Material and methods

2.1. Aerosol generator

As an aerosol generator a spark discharge generator (GFG 1000, Palas GmbH, Germany) was used. The aerosol is

produced by spark discharge between two graphite electrodes with a high purity (99.9995%). The gap between the

electrodes is kept constant automatically to compensate for the electrode consumption. To avoid the oxidation of carbon in

the created plasma an argon (purity 99.998%) stream is focused between the gaps for shielding and is also used as the carriergas for the particles. For all experiments the argon stream was adjusted to 3.8 l/min. Directly after the electrodes the aerosol

is diluted with dried particle-free air (5.5 l/min) to avoid further coagulation of the particles. The particle concentration as

well as the median of the particle size distribution can be changed by the discharge frequency ( Evans et al., 2003;Helsper

et al., 1993). For our setup it was varied between 7 Hz and 22 Hz. The composition and nanostructure of such produced

carbon aerosol has been comprehensively studied by (Knauer et al., 2009;Schuster et al., 2011). Additionally, this procedure

is a standardized aerosol generator (VDI 3491, Part 16).

2.2. Indirect photoelectric charger (IPC)

Figure 1 shows the indirect photoelectric charger (IPC) used as a unipolar charger in front of a differential mobility

analyzer. A Pen-Ray low pressure mercury lamp, emitting solely at 254 nm, is applied in the focus ( F1) of an elliptical mirror.

As an electron emitter a glassy carbon rod is fixed in the second focus (F2). Glassy carbon is used on account of its

photoelectron emission threshold in the range of the incident photon energy and the very inert surface with respect todegradation. This is essential to achieve a constant electron emission. The rod is covered with a quartz tube where the

B. Grob et al. / Journal of Aerosol Science 70 (2014) 5058 51

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aerosol is sucked through. A metal grid at the inner wall of the tube allows one to apply an electrical voltage between the

rod and the screen. The ion current arriving at the screen can be measured over an amplifier which keeps the grid virtually

at ground potential. In view of the fact that the carrier gas of the aerosol consists of a mixture of argon and air mainly

oxygen ions, or ion clusters of them, are formed by electron attachment which get attached to the particles by diffusion. This

technique allows a soft ion production without ozone production or the creation of undesired particles. It is also possible to

adjust the light intensity. Together with the ion concentration measurement, the drift of the ion generation process can be

followed and a stable charging process is achieved.To avoid multiple charged particles the lamp intensity was reduced to get a very low ion concentration (N t-product

about 2 105 s=cm3). The theoretically calculated fraction of singly charged particles was about 223% in the size

range of 1060 nm, whereas the fraction of doubly charged particles is smaller than 1%. More information about the

geometry and the detailed characterization of the IPC as well as the used theoretical calculations can be found inGrob et al.

(2013).

2.3. Diffusion battery

To check the calculated theoretical size per voltage of the differential mobility analyzer used in our setup a screen-type

diffusion battery was used (Model 3040, TSI Incorporated, USA). The used model is described in detail by Cheng & Yeh

(1980)andCheng et al. (1980). It consists of 10 stages connected in series. Every stage consists of a certain number of wire

mesh screens used as the collection surface. The aerosol is sucked through the whole battery. After every stage the decline of

penetration can be measured with a CPC over a switching valve. For monodisperse particles the logarithm of the penetrationp has a linear relation to the number of screens x.

logp ax 1

The factor a depends on the particle size. In a semilogarithmic plot the slope a can be easily determined by a fit. For a

polydisperse aerosol the evaluation gets a more complex curved manner (Lee, 1998). A calibration of the diffusion battery

was done with a differential mobility analyzer (DMA) for GFG-generated carbon particles to obtain a as a function of the

particle size. The size resolution for a size range of 1050 nm is in the range of 0.5 nm (Niessner, 1986).

2.4. Experimental setup for counting efficiency measurement and linearity check

The counting efficiency measurement setup (Fig. 2) consists of a spark discharge generator (GFG) as the aerosol

generator. Since the setup is not using a bipolar charger for neutralization all charged particles get removed by

the electrostatic precipitator (ESP) downstream of the GFG. As the GFG is operated with overpressure an excess flow isconnected to the ESP. The neutral fraction of the particles gets negatively charged with the IPC and is subsequently

separated in the DMA. The DMA runs with a dried particle-free sheath air stream of 5 l/min in the underpressure mode

and is a replica of the TSI long column cylindrical DMA (Model 3071, TSI Incorporated, USA) with a positive HV at the

central rod. The underpressure is produced by an ejector dilution system (VKL 10, Palas GmbH, Germany) sucking 0.5 l/min

through IPC and DMA. The dilution stream of the VKL 10 is 6.6 l/min which leads to a dilution factor of about 14. The

VKL 10 allows one to operate several particle counters downstream of the system without changing the dilution factor as

long as the total flow is lower than the total dilution flow. Over a tube distributor the additional systems are connected to

the VKL 10. To have the same response of all measurement devices at the same time, the tube length is adjusted to their

flow rates.

The counting efficiency of the regulation compliant CPC is measured versus a Faraday cup electrometer (FCE). The charge

number concentration is calculated by the following equation assuming singly charged particles:

nFCE IFCEeqFCE2

Fig. 1. Schematic drawing of the indirect photoelectric charger.


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The FCE is operated with a flow rate qFCE 2:9 l=min controlled with a critical orifice. Before every measurement the offset

of the amplifier was corrected and it was checked that there is no drift of the signal over time. The noise of the FCE current

(IFCE) is about 1 fA.

To check whether the charge number concentration is equal to the actual number concentration due to possible multiple

charged particles a reference CPC (TSI 3775, TSI Incorporated, USA) was installed parallel to the FCE. The reference CPC could

also be connected to the switching valve of the diffusion battery which was used to check the adjusted particle size of theDMA and the monodispersity of the size distribution.

Parallel to the reference CPC and FCE a second condensation particle counter was connected with a supposed cut off

according to the UN-ECE Regulation 83.

The counting efficiency of the regulation compliant CPC was calculated by the fraction of number concentration nCPCmeasured with the CPC and nFCE.

nCPCnFCE

3

The counting efficiency for a certain particle size was measured by taking the mean value of the concentrations measured

with a frequency of 1 Hz for 60 s. The standard deviation of was obtained forNdata points under consideration of Gaussian

error propagation

sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffiffiffiffiffiffiN

i 1i

2s s2

i; 4

where iare the individual measured values for nCPC, nFCEand si their standard deviation. All data was collected in parallel

with an analogdigital converter and recorded with a PC.

2.5. Setup for comparison (with Kr-85 charger)

For comparison only, a parallel setup was built up which is equal to the system described above, but it contained a

radioactive bipolar charger (Kr-85, approximately 95 MBq) for charge conditioning instead of the ESP and IPC and used a TSI

long column cylindrical DMA (Model 3071, TSI Incorporated, USA) operating with 20 l/min sheath air and 3 l/min sample air.

With this setup counting efficiencies were measured with a GFG aerosol as well as with a Combustion Aerosol Standard

(CAST) aerosol. The CAST implemented a dilution and an evaporation tube to remove the volatile species (AVL Particle

Generator, AVL LIST GmbH, Austria). For the realized experiments the evaporation tube as well as the first dilution step washeld constant at 314 K. At the inlet of the volatile particle remover the aerosol was diluted with dry particle free air with

Fig. 2. Setup to prove CPC calibration. The reference CPC TSI 3775 and the diffusion battery are optional to validate the CPC calibration system.


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a ratio of 1:3 by volume. After passing the evaporation tube a cold dilution (dilution factor: 4:1, ambient temperature

approximately 293 K) took place.

3. Results

The above-described system for measuring the counting efficiency of a UN-ECE Regulation 83 compliant CPC was

evaluated in detail. Three independent series of measurements have been performed, comparing the measured number

concentration of the reference CPC with the FCE, as well as applying a counting efficiency curve and a linearity check for theregulation compliant CPC. Additionally the results are compared with the conventional method using a radioactive source as

the charge-conditioner. Furthermore we checked the difference between the CAST aerosol and the GFG aerosol as the

calibration material.

3.1. Particle size control

At the beginning of every series of measurements the setup was checked by the diffusion battery in combination with the

reference CPC. As an exampleFig. 3shows for the three series the penetration through the screens versus the number of the

screens for 23-nm particles. By the linearity of the data in the semilogarithmic plot it can be seen that the penetration scales

with the exponential function of the screen number. The high coefficient of determination ( R240:999) indicates that the

data fits perfectly to the model and evidences the monodispersity of the aerosol. Moreover the very low standard deviation

between the slopes of 0.13% demonstrates the high repeatability of the system.

3.2. FCE compared to reference CPC

The key point for the usability of the indirect photoelectric charger as an alternative to a radioactive bipolar charger is the

number of multiple charged particles, which influence the charge number concentration directly. The charge number

concentration calculated by Eq.(1)has to be equal to the effective number concentration; otherwise a significant number of

multiple charged particles are present.Figure 4shows the number concentration measured with the reference CPC versus

the charge number concentration of the FCE for 55-nm particles. The different concentrations were achieved by adjusting

the discharge frequency of the GFG (between 7 Hz and 22 Hz). Again the perfect linearity demonstrates that there are no

unexpected errors or artifacts in the system. The low standard deviation of 0.5% of the mean value of the slopes indicates a

high repeatability of the calibration system. The deviation between the lines through origin and the mean value of the

slopes of the three lines is only 1.1%. Apparently the number of multiple charged particles is so low that there is no

significant effect measurable for this particles size.

3.3. Counting efficiency curve and linearity check of a UN-ECE Regulation 83 compliant CPC

Figure 5 shows the counting efficiency versus the particle size of the regulation compliant CPC for the three

measurements. All three data points for every particle size lie within the single standard deviation of every point. The

error bars significantly increase for particle sizes larger than 30 nm, due to the fact that the particle concentration was

Fig. 3. Particle size control by the diffusion battery for three measurements. The particle size was set to 23 nm at the DMA. The data was fitted for n 10data points for every single measurement (m 1). The gray lines indicate the expected lines for 22-nm and 24-nm particles.


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getting lower as the median of the size distribution of the spark discharge generator was about 23 nm. From 37 nm the

number concentration was kept over 5000 cm3 by adapting the discharge frequency of the GFG (about 3.522 Hz).

In Fig. 6 the linear response of the regulation compliant counter is shown for the three measurement series in the

concentration range of 1000 cm3

up to 10 000 cm3

. Taking into account the coefficients of determination of about 1, theregulation compliant CPC shows a perfect linear response. Nevertheless the slope reaches tightly the requirement value of

0.9. The very low variations are comparable to the other results described above.

3.4. New calibration system compared to conventional method

In view of the fact that the common setup for charge conditioning before an electrostatic classification is a bipolar

charger, a comparison was done between the IPC and a Kr-85 bipolar charger. As Fig. 7demonstrates there is no significant

difference between both methods in the range from 13 nm to 55 nm. All data points are the average of three single

measurement series, whereas the error bars are the single standard deviation in consideration of Gaussian error

propagation. For comparison the cutoff curve measured relative to the reference CPC is also plotted. The three curves

confirm the high repeatability as well as the negligible effect of multiple charged particles for the indirect photoelectriccharger.

Fig. 4. Number concentration of the reference CPC versus the charge number concentration of the FCE for a particle size of 55 nm. The linear fit includes

n 6 data points for every single measurement (m 1). The error bars show the single standard deviation.

Fig. 5. Counting efficiency measurement of a regulation compliant CPC with a supposed 50%-cut off of 23 nm. The error bars show the single standard

deviation in consideration of Gaussian error propagation.


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The average of three measurements of a CAST in combination with the Kr-85 charger is plotted as the fourth dataset in

Fig. 7. The evaporation tube implemented in the device was fixed at a temperature of 314 K. At this low temperature only

highly volatile materials are evaporated from the particles. It can be assumed that there are still hydrocarbons adsorbed onthe surface. Up to 35 nm the counting efficiency of the regulation compliant CPC with CAST soot is almost equal to the GFG

aerosol. For larger particles a difference to the mean values of the GFG is noticeable, whereas they are still within the single

standard deviation range of both methods. It has to be mentioned that in this size range the number concentration of the

CAST aerosol was only about 2000 cm3 after the VKL, which leads to a considerable error due to an average noise level of

the FCE of7400 cm3. At the relevant points of the regulation (23 nm & 41 nm) the difference between the GFG and the

CAST aerosol is 1% and 8%, respectively.

4. Discussion

The UN-ECE Regulation 83 for light duty vehicles as well as the UN-ECE Regulation 49 for heavy duty engines dictates

counting efficiencies at particle sizes (electrical mobility diameter) of 23 nm (71 nm) and 41 nm (71 nm) of 50% (712 %)

and 490%, respectively. As illustrated in the results previously it is possible with our calibration setup to validate a

regulation compliant counter in the size range from 13 nm up to 60 nm. The excellent agreement between the reference CPCand the charge number concentration measured with the FCE demonstrates that the indirect photoelectric charger in

Fig. 6. Linearity check of a regulation compliant CPC. The error bars show the single standard deviation.

Fig. 7. Comparison of the counting efficiency measurement between the Faraday cup electrometer and the CPC as reference. The third dataset shows the

mean value of three measurements with a comparable system but a Kr-85 bipolar charger for charge conditioning compared to the fourth where a CAST

aerosol was used. The error bars show the single standard deviation in consideration of Gaussian error propagation.


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combination with the ESP leads to a negligible fraction of multiple charged particles. Measurements with the bipolar

charger confirm the result. The high repeatability and the low standard deviation of the three datasets show that the

charging conditioner in combination with the GFG leads to a constant aerosol production with a stable charging process

over time. In fact the low number of multiple charged particles is only possible with a low charging efficiency of the unipolar

charger (low N t-product) but the number concentration the system delivers is still high enough for the calibration of a

CPC in the single counting mode up to 10 000 cm 3. Compared to other setups for calibration described in the literature our

system requires no dilution bridge. The concentration can be modified easily by adjusting the discharge frequency of

the GFG.As long as there is no calibration material prescribed for calibration in the regulation often emery oil or CAST is used.

It was reported byWang et al. (2010)andGiechaskiel et al. (2011)that the counting efficiency of emery oil is about 16% for

23 nm and 10% for 41 nm higher than for CAST particles. This strong discrepancy leads to significant differences in the total

number concentration measured for diesel engines (Wang et al., 2010). Therefore an inert material is needed which can be

delivered everywhere and is standardized. The CAST delivers particles generated by a flame soot generator operating with

propane and air. Since the aerosol is generated by combustion it may be close to a real diesel soot. However, it is very

difficult and complex to achieve a high repeatability of the particle composition. To achieve a repeatable particle surface and

the identical surface property, which is necessary for the condensation process in the CPC, volatiles have to be removed and

it has to be guaranteed that the morphology of the particles stays constant. This can only be done by a thermal treatment

and a costly flow control of the fuel, air and the quench gas stream.

The spark discharge generator equipped with carbon electrodes has the advantage that the particles consist of an

analytically pure material (purity 99.9995%, spectrograde quality) and is operated only with the noble gas argon as the

carrier gas. This allows the production of carbon particles with a highly repeatable morphology. The effect of volatiles on thecalibration process can be excluded. As evident from the results the GFG aerosol at least for a particle size of about 23 nm

leads to nearly the same response of the CPC as the CAST aerosol. For 41 nm the difference is still only about 8%. Therefore

for a CPC calibrated with a GFG a similar response to diesel soot can be expected when compared to a CPC calibrated with

a CAST.

The GFG 1000, operated with argon, yields much higher particle numbers than operated with nitrogen. This is due to a

much lower breakthrough threshold under sparking.

5. Conclusion

The described CPC calibration system allows the calibration or the periodical check of UN-ECE Regulation 83 compliant

counters. As a test aerosol generator a GFG 1000 was used which showed similar counting efficiencies as a CAST aerosol. For

charge conditioning an indirect photoelectric charger was implemented in combination with an electrostatic precipitator.This allowed the reproducible production of a monodisperse aerosol by an electrostatic classifier. Through an ejector diluter

the aerosol was sucked through the system and delivered a maximum sample flow of about 7 l/min. The response of the CPC

for calibration was compared with a Faraday cup electrometer.

The results demonstrated that the setup fulfills the required guidelines of the regulation and delivers a highly

reproducible monodisperse aerosol, whereas the concentration can be easily changed by the discharge frequency of the

GFG. Therefore the counting efficiency in a size range from 13 nm to 60 nm with particle concentrations between

1000 cm3 and 10 000 cm3 can be determined.

With the indirect photoelectric charger it is possible to replace usually used bipolar chargers containing radioactive

sources. Moreover by monitoring the ion current and the possibility to adapt the light power a stable process can be

achieved.

References

Cheng, Y., Keating, J., & Kanapilly, G. (1980). Theory and calibration of a screen-type diffusion battery. Journal of Aerosol Science, 11, 549556.Cheng, Y., & Yeh, H. (1980). Theory of a screen-type diffusion battery. Journal of Aerosol Science, 11, 313320.Evans, D.E., Harrison, R.M., & Ayres, J.G. (2003). The generation and characterisation of elemental carbon aerosols for human challenge studies. Journal of

Aerosol Science, 34, 10231041.Giechaskiel, B., & Bergmann, A. (2011). Validation of 14 used, re-calibrated and new TSI 3790 condensation particle counters according to the UN-ECE

Regulation 83. Journal of Aerosol Science, 42, 195203.Giechaskiel, B., Cresnoverh, M., Jrgl, H., & Bergmann, A. (2010). Calibration and accuracy of a particle number measurement system. Measurement Science

and Technology, 21, 045102.Giechaskiel, B., Dilara, P., & Andersson, J. (2008a). Particle measurement programme (PMP) light-duty inter-laboratory exercise: Repeatability and

reproducibility of the particle number method. Aerosol Science and Technology, 42, 528543.Giechaskiel, B., Dilara, P., Sandbach, E., & Andersson, J. (2008b). Particle measurement programme (PMP) light-duty inter-laboratory exercise: Comparison

of different particle number measurement systems. Measurement Science and Technology, 19, 095401.Giechaskiel, B., Wang, X., Gilliland, D., & Drossinos, Y. (2011). The effect of particle chemical composition on the activation probability in n-butanol

condensation particle counters. Journal of Aerosol Science, 42, 2037.Giechaskiel, B., Wang, X., Horn, H., Spielvogel, J., Gerhart, C., Southgate, J., Jing, L., Kasper, M., Drossinos, Y., & Krasenbrink, A. (2009). Calibration of

condensation particle counters for legislated vehicle number emission measurements. Aerosol Science and Technology, 43, 11641173.

Grob, B., Burtscher, H., & Niessner, R. (2013). Charging of ultra-fine aerosol particles by an ozone-free indirect uv photo-charger. Aerosol Science andTechnology, 47, 13251333.

http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref10http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref9http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref8http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref7http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref6http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref5http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref4http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref3http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref2http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref1

7/27/2019 1-s2.0-S0021850214000032-main.pdf

9/9

Helsper, C., Mlter, W., Lffler, F., Wadenpohl, C., Kaufmann, S., & Wenninger, G. (1993). Investigations of a new aerosol generator for the production ofcarbon aggregate particles. Atmospheric Environment: Part A General Topics, 27, 12711275.

Helsper, C., & Niessner, R. (1985). On the influence of the vapour substance on the behaviour of an expansion-type condensation nucleus counter. Journal ofAerosol Science, 16, 457461.

Knauer, M., Schuster, M.E., Su, D., Schloegl, R., Niessner, R., & Ivleva, N.P. (2009). Soot structure and reactivity analysis by Raman microspectroscopy,temperature-programmed oxidation, and high-resolution transmission electron microscopy. Journal of Physical Chemistry A, 113, 1387113880.

Kotzick, R., Panne, U., & Niessner, R. (1997). Changes in condensation properties of ultrafine carbon particles subjected to oxidation by ozone. Journal ofAerosol Science, 28, 725735.

Lee, K. (1998). Penetration of polydisperse aerosols through screen diffusion battery. Particulate Science and Technology, 16, 229238.

Mamakos, A., Giechaskiel, B., & Drossinos, Y. (2013). Experimental and theoretical investigations of the effect of the calibration aerosol material on thecounting efficiencies of TSI 3790 condensation particle counters. Aerosol Science and Technology, 47, 1121.Niessner, R. (1986). The chemical response of the photoelectric aerosol sensor (PAS) to different aerosol systems. Journal of Aerosol Science, 17, 705714.Schuster, M.E., Hvecker, M., Arrigo, R., Blume, R., Knauer, M., Ivleva, N.P., Su, D.S., Niessner, R., & Schlgl, R. (2011). Surface sensitive study to determine the

reactivity of soot with the focus on the European emission standards IV and VI. Journal of Physical Chemistry A, 115, 25682580.Sem, G.J. (2002). Design and performance characteristics of three continuous-flow condensation particle counters: a summary. Atmospheric Research, 62,

267294.Wang, X., Caldow, R., Sem, G.J., Hama, N., & Sakurai, H. (2010). Evaluation of a condensation particle counter for vehicle emission measurement:

Experimental procedure and effects of calibration aerosol material. Journal of Aerosol Science, 41, 306318.Wei, Q., Oestergaard, K., Porter, S., Ichiro, A., & Adachi, M. (2006). Real-time measuring system for engine exhaust solid particle number emission design

and performance. SAE Technical Paper 2006-01-0864.Wiedensohler, A., Orsini, D., Covert, D.S., Coffmann, D., Cantrell, W., Havlicek, M., Brechtel, F.J., Russell, L.M., Weber, R.J., Gras, J., Hudson, J.G., & Litchy, M.

(1997). Intercomparison study of the size-dependent counting efficiency of 26 condensation particle counters. Aerosol Science and Technology, 27,224242.

http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref22http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref20http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref19http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref18http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref17http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref16http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref15http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref14http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref13http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref12http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11http://refhub.elsevier.com/S0021-8502(14)00003-2/sbref11

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