Electromagnetic contributions to single-molecule sensitivity in surface-enhanced Raman scattering
Electromagnetic contributions to single-molecule sensitivity in surface-enhanced Raman scattering
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DOI：
10.1103/physreve.62.4318
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发表时间：
2000-09-01
影响因子：
2.4
通讯作者：
Apell, P
中科院分区：
文献类型：
--
作者：
Xu, HX;Aizpurua, J;Apell, P
我们研究是否可以在经典电磁理论的框架内解释表面增强拉曼散射（Sers）中的单分子灵敏度。研究了胶体颗粒的形状和大小、组分（Ag或Au）以及颗粒间的间距对Sers增强因子的影响。我们的计算表明，通过电磁可实现的最大增强因子是10（11）的顺序。这仅在特殊情况下获得，即在颗粒之间的间隙部位和尖锐表面突起外部的位置处。此类位点的相对罕见性，以及它们提供的增强的极端空间定位，可以定性地解释为什么只有很少的表面位点似乎对单分子Sers实验中的测量信号有贡献。在最近的实验中报道的10（14）-10（15）量级的增强因子可能涉及额外的增强机制，例如化学吸附诱导的共振拉曼效应。
We examine whether single molecule sensitivity in surface-enhanced Raman scattering (SERS) can be explained in the framework of classical electromagnetic theory. The influence of colloid particle shape and size, composition (Ag or Au) and interparticle separation distance on the wavelength-dependent SERS enhancement factor is reported. Our calculations indicate that the maximum enhancement factor achievable through electromagnetics is of the order 10(11). This is obtained only under special circumstances, namely at interstitial sites between particles and at locations outside sharp surface protrusions. The comparative rarity of such sites, together with the extreme spatial localization of the enhancement they provide, can qualitatively explain why only very few surface sites seem to contribute to the measured signal in single-molecule SERS experiments. Enhancement factors of the order 10(14)-10(15), which have been reported in recent experiments, are likely to involve additional enhancement mechanisms such as chemisorption induced resonance Raman effects.