Abstract:

We have observed Raman spectra of a very low frequency mode involving surface adsorbed molecules. Scattering from this mode appears to be sensitive to adsorbate orientation. With pyrazine as the adsorbate, the frequency shifts with electrochemical voltage, possibly because of changes in orientation of the molecule on the surface. With pyridine as the adsorbate, we find that the frequency of the peak in the scattered light intensity increases linearly with excitation frequency, suggesting that light is resonantly scattered from the surface adsorbed species.​​​​​​

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