Photoionization mass spectrometric studies of the isomeric transient species CH sub 2 SH and CH sub 3 S

Journal Article · Sat Aug 01 00:00:00 EDT 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.463169· OSTI ID:7281499

Ruscic, B; Berkowitz, J ^[1]

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1. Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

The products of the reaction of F atoms with CH{sub 3}SH are studied by photoionization mass spectrometry. Two thresholds, at 7.536{plus minus}0.003 eV and 9.262{plus minus}0.005 eV, are observed at mass 47, and identified with the adiabatic ionization potentials of CH{sub 2}SH and CH{sub 3}S, respectively. These conclusions are confirmed by additional experiments with CD{sub 3}SH, where an adiabatic ionization potential of 7.522{plus minus}0.003 eV is obtained at mass 49 (CD{sub 2}SH{sup +}) and a value of 9.268{plus minus}0.005 eV is found at mass 50 (CD{sub 3}S{sup +}). From an earlier appearance potential for CH{sub 2}SH{sup +} (CH{sub 3}SH) and the present ionization potential of CH{sub 2}SH, an upper limit for {ital D}{sub {ital d}0}{ital d} (H--CH{sub 2}SH ) of {le}93.97{plus minus}0.13 kcal/mol is deduced. By giving weight to the measured proton affinity of CH{sub 2}S, one obtains {ital D}{sub 0}(H--CH{sub 2}SH )=92.4{plus minus}2.0 kcal/mol. The corresponding S--H bond energy in CH{sub 3}SH derived from a recent kinetics-based value for {Delta}{ital H}{sup 0}{sub {ital f}{sub 0}}(CH{sub 3}S) is 86.1{plus minus}0.6 kcal/mol. A discrepancy in the difference of {Delta}{ital H}{sup 0}{sub {ital f}{sub 0}}(CH{sub 3}S{sup +}) and {Delta}{ital H}{sup 0}{sub {ital f}{sub 0}}(CH{sub 2}SH{sup +}) arising from recent theoretical and experimental determinations is resolved in favor of the {ital ab} {ital initio} values.

• DOE Contract Number: W-31-109-ENG-38
• OSTI ID: 7281499
• Journal Information: Journal of Chemical Physics; (United States), Vol. 97:3; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FLUORINE
ISOMERIZATION
METHYL RADICALS
SILANES
ADIABATIC PROCESSES
AFFINITY
ATOM-MOLECULE COLLISIONS
CHEMICAL BONDS
FAR ULTRAVIOLET RADIATION
FORMATION HEAT
IONIZATION POTENTIAL
MASS SPECTROMETERS
PHOTOIONIZATION
PROTONS
THRESHOLD ENERGY
ALKYL RADICALS
ATOM COLLISIONS
BARYONS
CHEMICAL REACTIONS
COLLISIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
ENTHALPY
FERMIONS
HADRONS
HALOGENS
HYDRIDES
HYDROGEN COMPOUNDS
IONIZATION
MEASURING INSTRUMENTS
MOLECULE COLLISIONS
NONMETALS
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHYSICAL PROPERTIES
RADIATIONS
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REACTION HEAT
SILICON COMPOUNDS
SPECTROMETERS
THERMODYNAMIC PROPERTIES
ULTRAVIOLET RADIATION
400500* - Photochemistry