Surface-enhanced hyper-Raman scattering (SEHRS) on Ag film over nanosphere (FON) electrodes: Surface symmetry of centrosymmetric adsorbates
Surface-enhanced hyper-Raman scattering (SEHRS) on Ag film over nanosphere (FON) electrodes: Surface symmetry of centrosymmetric adsorbates
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DOI：
10.1021/la0612264
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发表时间：
2006-12-05
期刊：
影响因子：
3.9
通讯作者：
Van Duyne, Richard P.
中科院分区：
文献类型：
--
作者：
Hulteen, John C.;Young, Matthew A.;Van Duyne, Richard P.
研究了中心对称分子在纳米球载银膜（AgFON）电极上的电化学表面增强超拉曼散射（SEHRS）和表面增强拉曼散射（Sers）。首次报道了反式-1，2-双（4-吡啶基）乙烯（BPE）在不同电位（vsAg/AgCl）下的SEHR谱，并证明了BPE的SEHR谱具有可逆电位调谐特性. SEHRS和Sers技术被用来确定在何种程度上无论是网站对称性降低或场梯度效应决定所观察到的振动光谱的起源。结果发现，研究的分子的SEHR和SER光谱在所有的频率区域在一个固定的电压是明显不同的，这表明吸附到AgFON表面后，中心对称性在很大程度上保留，场梯度效应可以忽略不计。这项工作还表明，SEHR光谱明显依赖于电位，而SER光谱基本上是独立的电位。它是确定的组合的变化Δ G（广告）和共吸附的抗衡离子的存在下，是负责改变局部对称性的吸附物，只有SEHRS的灵敏度，以检测这些变化的表面环境。因此，SEHRS是一种独特的有用的光谱工具，比Sers对局部吸附环境更敏感。
Electrochemical surface-enhanced hyper-Raman scattering (SEHRS) and surface-enhanced Raman scattering (SERS) of centrosymmetric molecules on Ag film over nanosphere (AgFON) electrodes are presented. The SEHR spectra of trans-1,2-bis(4-pyridyl) ethylene (BPE) at different potentials (vs Ag/AgCl) are presented for the first time, and a reversible potential tuning of the SEHR spectra of BPE is demonstrated. The SEHRS and SERS techniques were used to determine to what extent either site symmetry reduction or field gradient effects dictate the origin of the observed vibrational spectra. It is found that the SEHR and SER spectra for the molecules studied were distinctly different at all frequency regions at a fixed voltage, suggesting that centrosymmetry is largely retained upon adsorption to the AgFON surface and that field gradient effects are negligible. This work also shows that the SEHR spectra clearly depend on potential, whereas the SER spectra are essentially independent of potenial. It is determined that the combination of changes in Delta G(ads) and the presence of coadsorbed counterions are responsible for altering the local symmetry of the adsorbate and only SEHRS has the sensitivity to detect these changes in the surface environment. Thus, SEHRS is a uniquely useful spectroscopic tool that is much more sensitive to the local adsorption environment than is SERS.