Infrared absorption of CH3so2 detected with time-resolved Fourier-transform spectroscopy

Li Kang Chu, Yuan-Pern Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


A step-scan Fourier-transform spectrometer coupled with a 6.4 m multipass absorption cell was employed to detect time-resolved infrared absorption spectra of the reaction intermediate CH3SO2 radical, produced upon irradiation of a flowing gaseous mixture of CH3I and SO 2 in CO2 at 248 nm. Two transient bands with origins at 1280 and 1076 cm-1 were observed and are assigned to the SO 2-antisymmetric and SO2-symmetric stretching modes of CH3SO2, respectively. Calculations with density-functional theory (B3LYP/aug-cc-pVTZ and B3P86/aug-cc-pVTZ) predicted the geometry, vibrational, and rotational parameters of CH3SO2 and CH3OSO. Based on predicted rotational parameters, the simulated absorption band of the SO2-antisymmetric stretching mode that is dominated by the b-type rotational structure agrees satisfactorily with experimental results. In addition, a band near 1159 cm-1 observed at a later period is tentatively attributed to CH3SO2I. The reaction kinetics of CH3 + SO2→CH3SO 2 and CH3SO2+I→CH3SO 2I based on the rise and decay of absorption bands of CH 3SO2 and CH3SO2I agree satisfactorily with previous reports.

Original languageEnglish
Article number244301
Number of pages8
JournalJournal of Chemical Physics
Issue number24
StatePublished - 10 Jul 2006


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