Experimental and theoretical studies of isomeric CH[sub 3]S[sub 2] and CH[sub 3]S[sup +][sub 2]

Journal Article · Thu Mar 31 23:00:00 EST 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.467277· OSTI ID:5202162

Ma, Z; Liao, C L; Ng, C Y ^[1]; Cheung, Y; Li, W ^[2]; Baer, T ^[3]

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1. Ames Laboratory, USDOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)
2. Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T. (Hong Kong)
3. Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290 (United States)

By combining molecular beam photodissociation and photoionization measurements with [ital ab] [ital initio] Gaussian-2 (G2) calculations on the CH[sub 3]S[sub 2] and CH[sub 3]S[sup +][sub 2] systems, we have shown that CH[sub 3]SS is the dominant isomer formed in the photodissociation process, CH[sub 3]SSCH[sub 3]+[ital h][nu](193 nm) [r arrow]CH[sub 3]S[sub 2]+CH[sub 3]. The experimental ionization energy for CH[sub 3]SS (8.97[plus minus]0.02 eV) and the heat of formation at 0 K for CH[sub 3]SS[sup +] (217.7[plus minus]1.2 kcal/mol) are in excellent agreement with the G2 results. The photoionization efficiency spectrum observed for CH[sub 3]SS is also consistent with the theoretical prediction that the Franck--Condon factor for the photoionization process, CH[sub 3]SS+[ital h][nu] [r arrow]CH[sub 3]SS[sup +]+[ital e][sup [minus]], is not favorable. Based on the statistical modeling of experimental rates obtained previously for HS loss in the unimolecular decomposition of CH[sub 3]SSCH[sup +][sub 3] and the comparison with G2 [ital ab] [ital initio] predictions, we conclude that CH[sub 2]SSH[sup +] is most likely the isomer structure formed near the experimental appearance energy (11.07 eV) observed for the photodissociative ionization process, CH[sub 3]SSCH[sub 3]+[ital h][nu][r arrow]CH[sub 3]S[sup +][sub 2]+CH[sub 3]+[ital e][sup [minus]].

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5202162
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 100:7; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664200* -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALKYL RADICALS
BEAMS
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTIONS
EFFICIENCY
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ENTHALPY
FORMATION HEAT
IONIZATION
IONS
ISOMERIZATION
ISOMERS
MATHEMATICAL MODELS
METHYL RADICALS
MOLECULAR BEAMS
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
PHYSICAL PROPERTIES
RADIATIONS
RADICALS
REACTION HEAT
SPECTROSCOPY
STATISTICAL MODELS
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE ZERO K
THERMODYNAMIC PROPERTIES
ULTRAVIOLET RADIATION