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Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene
Author(s) -
Chen Jun,
Cao Maoqi,
Wei Bin,
Ding Mengmeng,
Shan Xiaobin,
Liu Fuyi,
Sheng Liusi
Publication year - 2016
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.3743
Subject(s) - chemistry , photoionization , cyclohexene , dissociation (chemistry) , photodissociation , mass spectrometry , fragmentation (computing) , ion , ionization , photochemistry , ultraviolet , atomic physics , physics , biochemistry , operating system , organic chemistry , chromatography , quantum mechanics , computer science , catalysis
In this work, photoionization and dissociation of cyclohexene have been studied by means of coupling a reflectron time‐of‐flight mass spectrometer with the tunable vacuum ultraviolet (VUV) synchrotron radiation. The adiabatic ionization energy of cyclohexene as well as the appearance energies of its fragment ions C 6 H 9 + , C 6 H 7 + , C 5 H 7 + , C 5 H 5 + , C 4 H 6 + , C 4 H 5 + , C 3 H 5 + and C 3 H 3 + were derived from the onset of the photoionization efficiency (PIE) curves. The optimized structures for the transition states and intermediates on the ground state potential energy surfaces related to photodissociation of cyclohexene were characterized at the ω B97X‐D/6‐31+g(d,p) level. The coupled cluster method, CCSD(T)/cc‐pVTZ, was employed to calculate the corresponding energies with the zero‐point energy corrections by the ω B97X‐D/6‐31+g(d,p) approach. Combining experimental and theoretical results, possible formation pathways of the fragment ions were proposed and discussed in detail. The retro‐Cope rearrangement was found to play a crucial role in the formation of C 4 H 6 + , C 4 H 5 + and C 3 H 5 + . Intramolecular hydrogen migrations were observed as dominant processes in most of the fragmentation pathways of cyclohexene. The present research provides a clear picture of the photoionization and dissociation processes of cyclohexene in the 8‐ to 15.5‐eV photon energy region. Copyright © 2016 John Wiley & Sons, Ltd.