Infrared Absorption Spectroscopy of Small Carbon−Sulfur Clusters Isolated in Solid Ar

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 1999-04, Vol.103 (16), p.2975-2981
• Main Authors: Szczepanski, Jan, Hodyss, Robert, Fuller, Jason, Vala, Martin
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp984700q

Small asymmetric and symmetric carbon−sulfur clusters, C n S and SC n S (n = 1−5), have been generated by pulsed laser ablation of a carbon/sulfur mixture, deposited in an argon matrix at 12 K, and studied via Fourier transform infrared absorption spectroscopy. Previous vibrational band assignments for a number of these clusters have been confirmed and new assignments for others have been made using a combination of isotopic (12C/13C) substitution and density functional (B3LYP/6-311G*) and ab initio (MP2) theoretical calculations. Reactions of neutral C n (n = 1−9) and C m S (m = 6−0) fragments are shown theoretically to be highly exothermic. Evidence for such aggregation reactions in the formation of the clusters is found from isotopomeric band intensities. Given their calculated vibrational band intensities and estimated column densities, it is proposed that the direct observation via IR spectroscopy of C5S and SC5S clusters in the envelope of the carbon star, IRC+10216, and, possibly, the Taurus molecular cloud, TMC-1, is an attractive possibility.