Atmospheric environment

A VUV photoionization mass spectrometric study on the OH-initiated photooxidation of isoprene with synchrotron radiation

Gang Pan , Changjin Hu , Mingqiang Huang , Zhenya Wang , Yue Cheng , Zhi Liu , Xuejun Gu , Weixiong Zhao , Weijun Zhang , Jun Chen , Fuyi Liu , Xiaobin Shan , Liusi Sheng


Received February 14, 2012,Revised May 14, 2012, Accepted , Available online December 07, 2012

Volume 24,2012,Pages 2075-2082

The gas-phase organic compounds resulting from OH-initiated photooxidation of isoprene have been investigated on-line by VUV photoionization mass spectrometry based on synchrotron radiation for the first time. The photoionization efficiency curves of the corresponding gaseous products as well as the chosen standards have been deduced by gating the interested peaks in the photoionization mass spectra while scanning the photon energy simultaneously, which permits the identification of the pivotal gaseous products of the photooxidation of isoprene, such as formaldehyde (10.84 eV), formic acid (11.38 eV), acetone (9.68 eV), glyoxal (9.84 eV), acetic acid (10.75 eV), methacrolein (9.91 eV), and methyl vinyl ketone (9.66 eV). Proposed reaction mechanisms leading to the formation of these key products were discussed, which were completely consistent with the previous works of different groups. The capability of synchrotron radiation photoionization mass spectrometry to directly identify the chemical composition of the gaseous products in a simulation chamber has been demonstrated, and its potential application in related studies of atmospheric oxidation of ambient volatile organic compounds is anticipated.

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