Vibrational energy relaxation of a polyatomic adsorbate on a metal surface: Methyl thiolate (CH3S) on Ag(111)

Alex Harris, L. Rothberg, L. Dhar, N. J. Levinos, L. H. Dubois

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Abstract

The lifetime of the first excited level of the symmetric C-H stretching mode of methyl thiolate (CH3S) bonded to Ag(1 1 1) is measured by populating the level with a picosecond infrared pulse and probing the population by transient sum frequency generation spectroscopy. The population transient shows a biexponential decay across the experimental temperature range from 110 to 380 K. The fast decay component has a lifetime of 2.5-3 ps at all temperatures. The slow relaxation component lifetime varies from 55 ps at 380 K to 90 ps at 110 K. Neither relaxation component shows decay rates that are compatible with direct energy transfer to phonons or electron-hole pairs of the metal substrate. Both relaxation components are instead assigned to intramolecular energy transfer to excited vibrational levels of other vibrational modes of the molecule.

Original languageEnglish
Pages (from-to)2438-2448
Number of pages11
JournalJournal of Chemical Physics
Volume94
Issue number4
Publication statusPublished - 1991

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ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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