Chowdhury Joydeep, Pal Prabir, Ghosh Manash, Misra T. N.
Department of Spectroscopy, Indian Association for the Cultivation of Science, Calcutta, 700 032, India
J Colloid Interface Sci. 2001 Mar 15;235(2):317-324. doi: 10.1006/jcis.2000.7358.
Surface-enhanced Raman scattering(SERS) of the Rhodamine 123 (Rh 123) molecule on ion-induced silver colloids has been studied. A time-dependent study of the SER spectra at a particular pH confirms charge transfer interaction between the probe molecule and the metal. The SER spectra of Rh 123 in Ag sol is compared with that of the molecules organized in a monolayer on silver island films by the Langmuir-Blodgett (LB) technique. The origin of high SERS activity of Rh 123 molecules in a monolayer on a silver island film is shown to be due to physisorption whereas in the ion-induced colloidal SERS both physisorption and chemisorption machanisms are involved. From these results, the contribution of charge transfer interaction to SERS in Ag sol has been estimated. In monolayer SERS, all the in-plane and out-of-plane (of xanthene ring) modes are more or less equally enhanced. This indicates that the xanthene plane of Rh 123 molecule organized in a LB film is oriented neither flat nor perpendicular to the silver island surface but is tilted. Copyright 2001 Academic Press.
研究了若丹明123（Rh 123）分子在离子诱导的银胶体上的表面增强拉曼散射（SERS）。在特定pH值下对SER光谱进行的时间相关研究证实了探针分子与金属之间的电荷转移相互作用。将Ag溶胶中Rh 123的SER光谱与通过朗缪尔-布洛杰特（LB）技术在银岛膜上以单层形式排列的分子的光谱进行了比较。结果表明，银岛膜上单层Rh 123分子具有高SERS活性的原因是物理吸附，而在离子诱导的胶体SERS中，物理吸附和化学吸附机制都起作用。根据这些结果，估算了电荷转移相互作用对Ag溶胶中SERS的贡献。在单层SERS中，所有面内和面外（呫吨环的）模式或多或少都得到了同等程度的增强。这表明，以LB膜形式排列的Rh 123分子的呫吨平面既不与银岛表面平行也不垂直，而是倾斜的。版权所有2001，学术出版社。
