Photoionization mass spectrometry of CH3SH, CD3SH, and CH3SD: Heats of formation of CH3S+(CH2SH+), CH2S+, CH2S, and HCS+
1982; American Institute of Physics; Volume: 77; Issue: 11 Linguagem: Inglês
10.1063/1.443756
ISSN1520-9032
AutoresR. E. Kutina, A. K. Edwards, G. L. Goodman, J. Berkowitz,
Tópico(s)Spectroscopy and Laser Applications
ResumoPhotoionization yield curves have been obtained for the major ions from CH3SH. Auxiliary studies with selectively deuterated species reveal that CD3S+ has a slightly lower threshold than CD2SH+ from CD3SH; but CH2SD+ has a lower threshold than CH3S+ from CH3SD. An analysis of alternative interpretations is presented. The isotopic studies also imply that CH2S+ is more stable than HCSH+, and HCS+ is more stable than CSH+. The value ΔH°f,0(HCS+)≤259.2±0.9 kcal/mol obtained in this study is in good agreement with a bracketed proton affinity for CS, but differs significantly from a recent ab initio calculation. This result confirms the view that HCS+ can be formed in interstellar clouds by exothermic reactions. The reaction CH3S+/CH2SH+→HCS++H2 proceeds weakly at threshold, and much more strongly after overcoming an activation barrier of ∼0.9 eV.
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