Dissociation dynamics of o-, p-, m-C7H7Br+ ions in the 8.5~12.5 eV energy range

XIA Yu; TANG Xiaofeng; WEN Zuoying; WU Xiangkun; WANG Chengcheng; GUO Xiaotian; LIU Fuyi; ZHANG Weijun

doi:10.3969/j.issn.0253-2778.2018.07.002

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Dissociation dynamics of o-, p-, m-C7H7Br+ ions in the 8.5~12.5 eV energy range

1.
School of Environmental Science & Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, China
2.
Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
3.
Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 , China
4.
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China

Cite this:

https://doi.org/10.3969/j.issn.0253-2778.2018.07.002

Received Date: 03 April 2018
Rev Recd Date: 22 May 2018
Publish Date: 31 July 2018

Abstract Full text PDF

Abstract

Abstract

The photoionization and dissociative photoionization of o-, p-, m-bromotoluene were investigated by utilizing synchrotron-based threshold photoelectron photoion coincidence spectroscopy (TPEPICO). Threshold photoelectron spectra (TPES), TPEPICO mass spectra and mass-selected TPEPICO spectra corresponding to each species were measured in the 8.5~12.5 eV energy range. The fundamental data including the ionization energy of bromotoluene molecules and the appearance energy of the C7H7+ fragment ions are acquired and agree well with previous literature results. Then based on the obtained average kinetic energy released in the dissociation and the existing potential energy surfaces, the dissociation mechanisms of o-, p-, m-bromotoluene ions are proposed. The bromotoluene ions with small internal energy will dissociate to benzyl ions and Br atoms after performance of inter-conversion to isomers, whereas those with large internal energy will directly fragment to the tolyl ions via the C-Br bond breaking.

Abstract

The photoionization and dissociative photoionization of o-, p-, m-bromotoluene were investigated by utilizing synchrotron-based threshold photoelectron photoion coincidence spectroscopy (TPEPICO). Threshold photoelectron spectra (TPES), TPEPICO mass spectra and mass-selected TPEPICO spectra corresponding to each species were measured in the 8.5~12.5 eV energy range. The fundamental data including the ionization energy of bromotoluene molecules and the appearance energy of the C7H7+ fragment ions are acquired and agree well with previous literature results. Then based on the obtained average kinetic energy released in the dissociation and the existing potential energy surfaces, the dissociation mechanisms of o-, p-, m-bromotoluene ions are proposed. The bromotoluene ions with small internal energy will dissociate to benzyl ions and Br atoms after performance of inter-conversion to isomers, whereas those with large internal energy will directly fragment to the tolyl ions via the C-Br bond breaking.