Selective Chemical Raman Enhancement for Organic Adsorbates at Metal Surfaces

ORAL

Abstract

It has long been observed that in surface enhanced Raman spectroscopy (SERS) relative mode intensities differ from gas- and solution-phase data, which obscures understanding of SERS in general. Using first-principles methods, we examine how chemisorption affects Raman scattering of molecules on metal surfaces relative to gas-phase, and provide a quantitative description of this effect. Calculated Raman spectra for benzene thiol bound at different sites on Au(111) show that chemical enhancement arises from the mode dependent electron-phonon coupling of the metal-molecule interface. Site-dependent enhancements are explained correlated to interfacial electronic structure. Comparison to experiments suggests affinity of benzene thiol for bridge sites on Au(111) surfaces.

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Authors

  • Alexey T. Zayak

    Molecular Foundry, LBNL, Berkeley, CA 94720, Department of Electrical Engineering and Computer Sciences, UC Berkeley, CA 94720, USA

  • Ying Hu

    Bioengineering Department, Rice University, Houston, TX 77005

  • Hyuck Choo

    Molecular Foundry, LBNL, Berkeley, CA 94720, Department of Electrical Engineering and Computer Sciences, UC Berkeley, CA 94720, USA

  • Stefano Cabrini

    Molecular Foundry, LBNL, Berkeley, CA 94720

  • P. James Schuck

    Molecular Foundry, LBNL, Berkeley, CA 94720

  • Jeff Neaton

    Molecular Foundry, LBNL, Berkeley, CA 94720, Molecular Foundry, LBNL, Molecular Foundry, Lawrence Berkeley National Lab, Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Laboratory