Issue 12, 2015

Characterization of molecular channel in photodissociation of SOCl2 at 248 nm: Cl2 probing by cavity ring-down absorption spectroscopy

Abstract

A primary elimination channel of the chlorine molecule in the one-photon dissociation of SOCl2 at 248 nm was investigated using cavity ring-down absorption spectroscopy (CRDS). By means of spectral simulation, the ratio of the vibrational population in the v = 0, 1, and 2 levels was evaluated to be 1 : (0.10 ± 0.02) : (0.009 ± 0.005), corresponding to a Boltzmann vibrational temperature of 340 ± 30 K. The Cl2 molecular channel was obtained with a quantum yield of 0.4 ± 0.2 from the X1A′ ground state of SOCl2via internal conversion. The dissociation mechanism differs from a prior study where a smaller yield of <3% was obtained, initiated from the 21A′ excited state. Temperature-dependence measurements of the Cl2 fragment turn out to support our mechanism. With the aid of ab initio potential energy calculations, two dissociation routes to the molecular products were found, including one synchronous dissociation pathway via a three-center transition state (TS) and the other sequential dissociation pathway via a roaming-mediated isomerization TS. The latter mechanism with a lower energy barrier dominates the dissociation reaction.

Graphical abstract: Characterization of molecular channel in photodissociation of SOCl2 at 248 nm: Cl2 probing by cavity ring-down absorption spectroscopy

Article information

Article type
Paper
Submitted
24 Dec 2014
Accepted
06 Feb 2015
First published
10 Feb 2015

Phys. Chem. Chem. Phys., 2015,17, 7838-7847

Author version available

Characterization of molecular channel in photodissociation of SOCl2 at 248 nm: Cl2 probing by cavity ring-down absorption spectroscopy

B. Chen, P. Tsai, T. Huang, Z. Xia, K. Lin, C. Chiou, B. Sun and A. H. H. Chang, Phys. Chem. Chem. Phys., 2015, 17, 7838 DOI: 10.1039/C4CP06043A

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