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Photoionization mass spectrometry of CH/sub 3/SH, CD/sub 3/SH, and CH/sub 3/SD: Heats of formation ofCH/sub 3/S/sup +/(CH/sub 2/SH/sup +/), CH/sub 2/S/sup +/, CH/sub 2/S, and HCS/sup +/

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:6715951
; ; ;

Photoionization yield curves have been obtained for the major ions from CH/sub 3/SH. Auxiliary studies with selectively deuterated species reveal that CD/sub 3/S/sup +/ has a slightly lower threshold than CD/sub 2/SH/sup +/ from CD/sub 3/SH; but CH/sub 2/SD/sup +/ has a lower threshold than CH/sub 3/S/sup +/ from CH/sub 3/SD. An analysis of alternative interpretations is presented. The isotopic studies also imply that CH/sub 2/S/sup +/ is more stable than HCSH/sup +/, and HCS/sup +/ is more stable than CSH/sup +/. The value ..delta..H/sup 0//sub f/,0(HCS/sup +/)< or =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/sup +/ can be formed in interstellar clouds by exothermic reactions. The reaction CH/sub 3/S/sup +//CH/sub 2/SH/sup +/..-->..HCS/sup +/+H/sub 2/ proceeds weakly at threshold, and much more strongly after overcoming an activation barrier of approx.0.9 eV.

Research Organization:
Argonne National Laboratory, Argonne, Illinois 60439
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
6715951
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 77:11; ISSN JCPSA
Country of Publication:
United States
Language:
English

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Related Subjects

640302* -- Atomic
Molecular &amp; Chemical Physics-- Atomic &amp; Molecular Properties &amp; Theory
74 ATOMIC AND MOLECULAR PHYSICS
CHARGED PARTICLES
ENTHALPY
FORMATION HEAT
IONIZATION
IONS
MASS SPECTROSCOPY
MOLECULAR IONS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOTOIONIZATION
PHYSICAL PROPERTIES
REACTION HEAT
SPECTROSCOPY
THERMODYNAMIC PROPERTIES