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Effects of Atomic Geometry and Electronic Structure of Platinum Surfaces on Molecular Adsorbates Studied by Gap-Mode SERS
journal contribution
posted on 2014-07-23, 00:00 authored by Jian Hu, Masahiro Tanabe, Jun Sato, Kohei Uosaki, Katsuyoshi IkedaSurface
enhanced Raman scattering (SERS) spectra of organic monolayers
were measured on various types of polycrystalline and single crystalline
Pt substrates with nanometric or atomic surface features, including
heteroepitaxial Pt monolayers, using sphere-plane type nanogap structures.
Although atomic geometry and electronic structures of a metal surface
significantly influence metal–molecule interactions, such effects
are often hindered in conventional SERS measured on a roughened surface
because of the spectral information averaging at various adsorption
sites. In this study, the use of atomically defined Pt surfaces revealed
detailed surface effects; the observed preferential adsorption geometry
on each surface was well explained by atomic surface arrangements.
The peak shift of the intramolecular vibration in the anchor group
was in good agreement with the variation of the d-band center of Pt
substrates. Moreover, in electrochemical SERS study the Stark shift
of an extramolecular vibrational mode at around 400 cm–1, which is not accessible in infrared absorption spectroscopy, was
monitored on an atomically defined heteroepitaxial Pt monolayer electrode.