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(1+1) Resonance‐Enhanced Multiphoton Ionization and Photodissociation Study of CS 2 via the 1 B 2 State
Author(s) -
Hu Zhengfa,
Lee WeiBin,
Zhang XiaoPeng,
Wei PeiYing,
Lin KingChuen
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700620
Subject(s) - resonance enhanced multiphoton ionization , photodissociation , ionization , chemistry , dissociation (chemistry) , analytical chemistry (journal) , spectral line , branching fraction , mass spectrometry , atomic physics , spectroscopy , photoionization , ion , photochemistry , physics , organic chemistry , chromatography , astronomy , quantum mechanics
(1+1) resonance‐enhanced multiphoton ionization (REMPI) spectra of CS 2 and molecular dissociation dynamics are investigated using a time‐of‐flight mass spectrometer equipped with velocity imaging detection. The REMPI spectra via a linear‐bent ${{}^1\Sigma _g^ + }$ → 1 B 2 ( ${{}^1\Sigma _u^ + }$ ) transition are acquired in the wavelength range of 208–217 nm. Each ro‐vibrational band profile of the 1 B 2 ( ${{}^1\Sigma _u^ + }$ ) state is deconvoluted to yield the corresponding predissociative lifetime from 0.3 to 3 ps. Upon excitation at 210.25 and 212.54 nm, the resulting images of S + and CS + fragments are analyzed to give individual translational energy distributions, which are resolved into two components corresponding to the CS+S( 3 P) and CS+S( 1 D) channels. The product branching ratios of S( 3 P)/S( 1 D) are evaluated to be 5.7±1.0 and 9.6±2.5 at 210.25 and 212.54 nm, respectively. Despite the difficulty avoiding the effect of multiphoton absorption, the molecular dissociation channel is verified to prevail over the dissociative ionization channel of CS 2 . The anisotropy parameters for the triplet and singlet channels are determined to be ∼0.8 and 1.1–1.3, respectively, suggesting that the predissociative state should have a bent configuration with a short lifetime.