Atmos. Chem. Phys. Discuss., 11, 25871-25907, 2011
© Author(s) 2011. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Analysis of high mass resolution PTR-TOF mass spectra from 1,3,5-trimethylbenzene (TMB) environmental chamber experiments
M. Müller1, M. Graus1,*, A. Wisthaler1, A. Hansel1, A. Metzger2, J. Dommen3, and U. Baltensperger3
1Institute of Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
2Ionicon Analytik Gesellschaft m.b.H, Innsbruck, Austria
3Paul Scherrer Institut, Villigen, Switzerland
*current address: Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO, USA

Abstract. A series of 1,3,5-trimethylbenzene (TMB) photo-oxidation experiments was performed in the 27-m3 Paul Scherrer Institute environmental chamber under various NOx conditions. A University of Innsbruck prototype high resolution Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-TOF) was used for measurements of gas and particulate phase organics. The gas phase mass spectrum displayed ~200 ion signals during the TMB photo-oxidation experiments. Molecular formulas CNmHnNoOp were determined and ion signals were separated and grouped according to their C, O and N numbers. This allowed to determine the time evolution of the O:C ratio and of the average carbon oxidation state OSC of the reaction mixture. Both quantities were compared with master chemical mechanism (MCMv3.1) simulations. The O:C ratio in the particle phase was about twice the O:C ratio in the gas phase. Average carbon oxidation states of secondary organic aerosol (SOA) samples OSCSOA were in the range of −0.34 to −0.31, in agreement with expected average carbon oxidation states of fresh SOA (OSC = −0.5 − 0).

Citation: Müller, M., Graus, M., Wisthaler, A., Hansel, A., Metzger, A., Dommen, J., and Baltensperger, U.: Analysis of high mass resolution PTR-TOF mass spectra from 1,3,5-trimethylbenzene (TMB) environmental chamber experiments, Atmos. Chem. Phys. Discuss., 11, 25871-25907, doi:10.5194/acpd-11-25871-2011, 2011.
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