title: Ultrafast dynamics of surface-enhanced Raman scattering due to Au nanostructures.
abstract: Ultrafast dynamics of surface-enhanced Raman scattering (SERS) was investigated at cleaved graphite surfaces bearing deposited gold (Au) nanostructures (∼10 nm in diameter) by using sensitive pump-probe reflectivity spectroscopy with ultrashort (7.5 fs) laser pulses. We observed enhancement of phonon amplitudes (C═C stretching modes) in the femtosecond time domain, considered to be due to the enhanced electromagnetic (EM) field around the Au nanostructures. Finite-difference time-domain (FDTD) calculations confirmed the EM enhancement. The enhancement causes drastic increase of coherent D-mode (40 THz) phonon amplitude and nanostructure-dependent changes in the amplitude and dephasing time of coherent G-mode (47 THz) phonons. This methodology should be suitable to study the basic mechanism of SERS and may also find application in nanofabrication.
authors: Interdisciplinary Research Center, Yokohama National University, Yokohama, Kanagawa 240-8501, Japan.
authors: Ikufumi
authors: I
authors: Katayama
authors: Sho
authors: S
authors: Koga
authors: Ken-ichi
authors: K
authors: Shudo
authors: Jun
authors: J
authors: Takeda
authors: Toru
authors: T
authors: Shimada
authors: Atsushi
authors: A
authors: Kubo
authors: Shunichi
authors: S
authors: Hishita
authors: Daisuke
authors: D
authors: Fujita
authors: Masahiro
authors: M
authors: Kitajima