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 sulphuric acid in the CLOUD experiment at CERN
T2  - Atmospheric measurement techniques discussions
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., with and without the presence of ions, were carried out under precisely controlled conditions. The sulphuric acid concentration was measured with a Chemical Ionization 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 sulphuric 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 (GCR) or the proton synchrotron (PS) pion beam for the ion generation, respectively. The ion effect typically involved an increase in the apparent sulphuric acid concentration by a factor of ~2 to 3 and was qualitatively verified by the ion measurements by 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 one second. In order to exclude the ion effect and to provide corrected sulphuric acid concentrations during the GCR and PS beam nucleation experiments, a parameterisation was derived that utilizes the trace gas concentrations and the UV light intensity as input parameters. Atmospheric sulphuric acid measurements with a CIMS showed an insignificant ion effect.
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/37233
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-372334
SN  - 1867-8610
N1  - © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License.
VL  - 7
SP  - 6595
EP  - 6624
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -