Surface-Enhanced Raman Spectroscopy as a Probe of Adsorbate-Surface Bonding: Simple Alkenes and Alkynes Adsorbed at Gold Electrodes
PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY
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The interaction of various alkenes with gold electrodes has been studied using surface-enhanced Raman spectroscopy SERS. Large decreases, from 70 to 140cm, were observed in the C-C double bond and C triple bond C stretching frequencies upon adsorption which are attributed to adsorbate-surface bonding involving these groups. The potential dependence of these SERS frequencies suggests that the Pi yield s sigma band overlap is more prevalent than the d yields pi pi bond interaction. Carbon-hydrogen stretching vibrations, nuC-H, as well as other skeletal modes were also detected for the adsorbates paraffinic, olefinic, and aromatic nuC-H modes could readily be distinguished although acetylenic nuCH modes were too weak to be detected. Generally, the most intense SERS bands relative to those in the bulk-phase spectra are associated with vibrations of the carbon-carbon double or triple bonds. Attempts to examine SERS of adsorbated acetylene were thwarted by a spontaneous surface reaction yielding a film of polyacetylene.
- Atomic and Molecular Physics and Spectroscopy