EDP Sciences
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Volume 395, Number 3, December I 2002
Page(s) 1031 - 1044
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20021328

A&A 395, 1031-1044 (2002)
DOI: 10.1051/0004-6361:20021328

A comprehensive investigation on the formation of organo-sulfur molecules in dark clouds via neutral-neutral reactions

M. Yamada1, Y. Osamura1 and R. I. Kaiser2

1  Department of Chemistry, Rikkyo University, 3-34-1 Nishi-ikebukuro, Tokyo 171-8501, Japan
2  Department of Chemistry, University of York, YO10 5DD, UK

(Received 11 June 2002 / Accepted 9 September 2002 )

Fifteen reactions on the doublet HC nS and singlet/triplet ${\rm H_2C}_n{\rm S} (n=1,2)$ potential energy surfaces have been investigated theoretically via electronic structure calculations to unravel the formation of hydrogen deficient, sulfur bearing molecules via bimolecular reactions of two neutral species in cold molecular clouds. Various barrierless reaction pathways to synthesize astronomically observed ${\rm C}_n{\rm S}$ and hitherto undetected ${\rm HC}_n{\rm S} (n=1,2)$ isomers are offered. These data present important guidance to search for rotational transitions of the elusive thioformyl $\rm HCS(X^2A')$ and thioketenyl $\rm HCCS(X^2\Pi)$ radicals in the interstellar medium.

Key words: astrochemistry -- ISM: molecules -- molecular processes -- methods: miscellaneous

Offprint request: Y. Osamura, osamura@rikkyo.ac.jp

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