Chemical Raman Enhancement of Organic Adsorbates on Metal Surfaces

Abstract

Using a combination of first-principles theory and experiments, we provide a quantitative explanation for chemical contributions to surface-enhanced Raman spectroscopy for a well-studied organic molecule, benzene thiol, chemisorbed on planar Au(111) surfaces. With density functional theory calculations of the static Raman tensor, we demonstrate and quantify a strong mode-dependent modification of benzene thiol Raman spectra by Au substrates. Raman active modes with the largest enhancements result from stronger contributions from Au to their electron-vibron coupling, as quantified through a deformation potential, a well-defined property of each vibrational mode. A straightforward and general analysis is introduced that allows extraction of chemical enhancement from experiments for specific vibrational modes; measured values are in excellent agreement with our calculations.

5 pages, 4 figures and Supplementary material included as ancillary file

References in corpus (1)

• Simultaneous measurements of electronic conduction and Raman response in molecular junctions

Cited by in corpus (4)

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• Plasmons in nanoscale metal junctions: optical rectification and thermometry