TY  - JOUR
A1  - Rondo, Linda
A1  - Kürten, Christoph Andreas
A1  - Ehrhart, Sebastian
A1  - Schobesberger, Siegfried
A1  - Franchin, Alessandro
A1  - Junninen, Heikki
A1  - Petäjä, Tuukka
A1  - Sipilä, Mikko
A1  - Worsnop, Douglas R.
A1  - Curtius, Joachim
T1  - Effect of ions on the measurement of sulfuric acid in the CLOUD experiment at CERN
T2  - Atmospheric measurement techniques
N2  - Ternary aerosol nucleation experiments were conducted in the CLOUD chamber at CERN in order to investigate the influence of ions on new particle formation. Neutral and ion-induced nucleation experiments, i.e. without and with the presence of ions, respectively, were carried out under precisely controlled conditions. The sulfuric acid concentration was measured with a chemical ionisation mass spectrometer (CIMS) during the new particle formation experiments. The added ternary trace gases were ammonia (NH3), dimethylamine (DMA, C2H7N) or oxidised products of pinanediol (PD, C10H18O2). When pinanediol was introduced into the chamber, an increase in the mass spectrometric signal used to determine the sulfuric acid concentration (m/z 97, i.e. HSO4−) was observed due to ions from the CLOUD chamber. The enhancement was only observed during ion-induced nucleation measurements by using either galactic cosmic rays (GCRs) or the proton synchrotron (PS) pion beam for the ion generation, respectively. The ion effect typically involved an increase in the apparent sulfuric acid concentration by a factor of ~ 2 to 3 and was qualitatively verified by the ion measurements with an atmospheric-pressure interface-time of flight (APi-TOF) mass spectrometer. By applying a high-voltage (HV) clearing field inside the CLOUD chamber, the ion effect on the CIMS measurement was completely eliminated since, under these conditions, small ions are swept from the chamber in about 1 s. In order to exclude the ion effect and to provide corrected sulfuric acid concentrations during the GCR and PS beam nucleation experiments, a parameterisation was derived that utilises the trace gas concentrations and the UV light intensity as input parameters. Atmospheric sulfuric acid measurements with a CIMS showed an insignificant ion effect.
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/37234
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-372344
SN  - 1867-8548
SN  - 1867-1381
N1  - © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License.
VL  - 7
IS  - 11
SP  - 3849
EP  - 3859
PB  - Copernicus
CY  - Katlenburg-Lindau
ER  -