10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Chemical Composition of Atmospheric Ion Clusters Measured with the New ioniAPi-TOF
Markus Leiminger, Paul Mutschlechner, Daniel Gunsch, Arttu Ylisirniö, Stefan Feil, Alfons Jordan, Siegfried Schobesberger, Armin Hansel, GERHARD STEINER, University of Innsbruck
Abstract Number: 893 Working Group: Instrumentation
Abstract The Atmospheric-Pressure-interface developed by Tofwerk AG, Thun (Switzerland), for Time-of-Flight mass spectrometry (APi-TOF MS) is a technique especially suited to the detection of very low number concentrations of ions (a few hundred per cubic centimetre) in the atmosphere for subsequent identification of their chemical composition.
The Atmospheric-Pressure-interface of the new ioniAPi-TOF from Ionicon Analytik GmbH, consists of two hexapole ion guides, followed by an Einzel-lens system and an orthogonal acceleration time-of-flight mass analyser. The mass resolution m/Δm of the instrument is larger than 2000 (FWHM) with a total ion transmission of about 1%. The hexapoles used in this instrument allow for an almost constant ion transmission over a wider mass range than observed before. In the context of atmospheric ion clusters, this means that not only high-mass cluster ions, but also the composition of precursor compounds and gas-phase impurities can be measured simultaneously. Using hexapole ion guides in the ioniAPi-TOF results in rather low fragmentation of weakly bonded cluster ions. Increasing the DC voltage of the second hexapole allows the study of collision induced fragmentation of weakly bonded cluster ions.
We will present first results of the positive ion composition obtained under very well controlled conditions during the CLOUD 12 campaign in fall 2017 at CERN, studying the influence of galactic cosmic rays on new particle formation. In addition, we will show results from an inter-comparison with the Tofwerk AG quadrupole APi-TOF of the University of Eastern Finland and discuss differences in the lower mass range <100 Th and similarities in the operational performance of the instruments in the mass range > 100 Th.
Acknowledgements: We thank the CLOUD collaboration (www.cern.ch/cloud) for the opportunity to test the new prototype instrument and for their support. This work is funded by the Austrian Science Fund, FWF (project no. P27295-N20), the Tiroler Wissenschaftsfonds (nanoTOF-ICE) and the University of Innsbruck promotion grant for young researchers.