Formation of interstellar CCS and CCCS: a case for radical/neutral chemistry?
Abstract
Pathways to the abundant sulphur-containing carbon chain molecules, CCS and CCCS, are examined. The previously proposed ion/molecule mechanisms for the formation of these species appear satisfactory in the case of CCS, but arguments for the formation of CCCS via ion/molecule reactions rely on several assumptions which do not appear justified in the absence of sufficient experimental evidence. Alternative, radical/neutral pathways to CCS and CCCS (namely the reactions of C_2H with S, and with CS respectively) are proposed which can account for the observed high abundances of these species within TMC-1 and other objects. Thermochemical aspects of the various C_xS production mechanisms are assessed in the light of recent ab initio calculations on the chemical species concerned. Experimental study of the reaction of C_2H with CS is strongly urged.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 1996
- DOI:
- 10.1093/mnras/281.2.666
- Bibcode:
- 1996MNRAS.281..666P
- Keywords:
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- MOLECULAR PROCESSES;
- CIRCUMSTELLAR MATTER;
- ISM: ABUNDANCES;
- ISM: CLOUDS;
- ISM: MOLECULES