Penning ionization of CH3SCH3, CH3SSCH3, and CH3CH2SH by collision with He*(23S) metastable atoms

Naoki Kishimoto, Ryoji Yokoi, Hideo Yamakado, Koichi Ohno

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25 Citations (Scopus)


Penning ionization of CH3SCH3 (dimethyl thioether), CH3SSCH3 (dimethyl disulfide), and CH3CH2SH (ethyl thioalcohol) upon collision with He*(23S) metastable atoms was studied by two-dimensional (electron-energy/ collision-energy-resolved) Penning ionization electron spectroscopy. A collision energy dependence of the partial ionization cross sections has indicated that the interaction potentials are anisotropic between He*(23S) and the target molecules. For CH3SCH3 and CH3CH2SH, the interaction potential around the sulfur atom was found to be more attractive for the out-of-plane direction vertical to the CSC or CCS plane than for the in-plane direction, while the opposite trend was observed around the oxygen atom of CH3CH2OH. Anisotropic potential for CH3SSCH3 was found to be similar to that for CH3SCH3. Strongly enhanced bands in Penning ionization electron spectra of sulfur compounds, which were assigned to ionization from molecular orbitals having sulfur 3s (S3s) atomic orbital character, were found to be associated with an intermolecular excitation transfer from He* to the target molecule and also with the following intramolecular Auger-like autoionization process.

Original languageEnglish
Pages (from-to)3284-3292
Number of pages9
JournalJournal of Physical Chemistry A
Issue number18
Publication statusPublished - 1997 May 1


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