拉曼散射
波长
材料科学
激发
偶极子
散射
分子物理学
电场
离散偶极子近似
光学
瑞利散射
原子物理学
拉曼光谱
化学
物理
光电子学
量子力学
有机化学
作者
Milton Kerker,Dau-Sing Wang,H. Chew
出处
期刊:Applied optics
[The Optical Society]
日期:1980-12-15
卷期号:19 (24): 4159-4159
被引量:445
摘要
A model for Raman scattering by a molecule adsorbed at the surface of a spherical particle is articulated by treating the molecule as a classical electric dipole. This follows Moskovits’s suggestion [ J. Chem. Phys.69, 4159 ( 1978)] and the experiments by Creighton [ J. Chem. Soc. Faraday Trans. II, 75, 790 ( 1979)] that such a system may exhibit SERS similar to that at roughened electrode surfaces. The molecule is stimulated by a primary field comprised of the incident and near-scattered fields. Emission consists of the dipole field plus a scattered field, each at the shifted frequency. Addition of feedback terms between the dipole and the particle makes only a negligible contribution to the fields. For pyridine adsorbed at the surface of a silver sphere, the 1010-cm−1 band is enhanced by ~106 if the radius is much less than the wavelengths and the excitation wavelength is ~382 nm, a wavelength for which the relative refractive index of silver is close to m = √2i. Detailed results are given for the effect upon the angular distribution and the polarization of the Raman emission of particle size, distance from the surface, excitation wavelength, and location of the molecule upon the surface. These results simulate those observed at roughened silver electrodes and suggest that the mechanism of SERS at those electrodes may resemble the electromagnetic mechanism elucidated here. We predict that comparable effects should be observed for fluorescent scattering.
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