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Multiphoton dissociation/ionization of CHCl 3 and CFCl 3 at 355 nm: an experimental and theoretical study
Author(s) -
Sharma P.,
Vatsa R. K.,
Maity D. K.,
Kulshreshtha S. K.
Publication year - 2004
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1638
Subject(s) - chemistry , photoionization , dissociation (chemistry) , ionization , fragmentation (computing) , mass spectrometry , photodissociation , ion , molecule , polyatomic ion , ground state , infrared multiphoton dissociation , ab initio , analytical chemistry (journal) , photochemistry , atomic physics , organic chemistry , chromatography , physics , computer science , operating system
Nonresonant laser‐induced multiphoton dissociation/ionization studies have been conducted for trichloromethane (CHCl 3 ) and trichlorofluoromethane (CFCl 3 ) at 355 nm, using time‐of‐flight mass spectrometry (TOFMS). The molecular ion signal was found to be missing for both these compounds, and very similar fragmentation patterns were observed. Ab initio molecular electronic structure calculations were performed to help understand the fragmentation pattern of these molecules in the laser field. The energetics of different dissociation channels in the ground states of [CHCl 3 ] + . , [CHCl 2 ] + , [CFCl 3 ] + . and [CFCl 2 ] + , as well as neutral CHCl 3 , CHCl 2 . , CFCl 3 and CFCl 2 .systems, were calculated. On comparing theoretical results with experimentally observed ion signals and their relative abundances in TOFMS, it is inferred that these molecules undergo sequential Cl atom elimination followed by photoionization of the fragments. The absence of [CFCl] + has been interpreted on the basis of resonant à state‐mediated two‐photon absorption by CFCl, and the subsequent prompt photodissociation processes occurring for this state. Copyright © 2004 John Wiley & Sons, Ltd.