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Contribution of Charge‐Transfer Mechanisms to Surface‐Enhanced Raman Scattering with Near‐IR Excitation
Author(s) -
Zhou Qun,
Chao Yanwen,
Li Yan,
Xu Wei,
Wu Ying,
Zheng Junwei
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600776
Subject(s) - raman scattering , materials science , molecule , electrode , plasmon , nanoparticle , adsorption , indium tin oxide , excitation , surface plasmon resonance , raman spectroscopy , metal , chemical physics , analytical chemistry (journal) , photochemistry , chemistry , optoelectronics , nanotechnology , optics , physics , electrical engineering , organic chemistry , engineering , chromatography , metallurgy
Surface‐enhanced Raman scattering under near‐IR excitation is investigated for p ‐aminothiophenol (PATP) molecules that are either adsorbed on an electrochemically roughened silver electrode or embedded in an Au/PATP/Ag molecular junction assembled on an indium‐doped tin oxide electrode. The contribution from chemical enhancement can be amplified relative to the contribution from electromagnetic enhancement, because the energy of the near‐IR excitation is far from the surface plasmon resonance of the nanosized metal particles. The energy required for the charge‐transfer process for the Au/PATP/Ag molecular junction is much lower than that of the PATP molecules adsorbed on the electrochemically roughened silver electrode. Coadsorption of chloride ions on the metal nanoparticles may result in an alteration of the local Fermi level of the metal nanoparticles, thus leading to better energy matching between the energy level of the interconnecting PATP molecules and the Fermi level of the metal nanoparticles.