Kim Kwan, Lee Hyun Sook
Laboratory of Intelligent Interfaces, School of Chemistry, Seoul National University, Seoul 151-742, Korea.
J Phys Chem B. 2005 Oct 13;109(40):18929-34. doi: 10.1021/jp052665z.
Raman scattering measurements were conducted for 4-aminobenzenethiol (4-ABT) assembled on powdered copper substrates. Initially, very weak Raman peaks were detected, but upon attaching Ag nanoparticles probably via NH2 groups onto 4-ABT/Cu, distinct Raman spectra were observed. Considering the fact that no Raman peak was identified when Ag nanoparticles were adsorbed on 4-aminophenyl-derivatized silane monolayers assembled on silica powders, the Raman spectra observed for Ag@4-ABT/Cu should be surface-enhanced Raman scattering (SERS) spectra, occurring by an electromagnetic coupling of the localized surface plasmon of Ag nanoparticles with the surface plasmon polariton of Cu powders. The extra enhancement factor attainable by the attachment of a single Ag nanoparticle is estimated to be as large as 1.4 x 10(5) in the case when 632.8-nm radiation is used as the excitation source. When Au nanoparticles were attached onto 4-ABT/Cu, at least an order of magnitude weaker Raman spectra were obtained at all excitation wavelengths, however, indicating that the Au-to-Cu coupling should be far less effective than the Ag-to-Cu coupling for the induction of SERS.
对组装在粉末状铜基底上的4-氨基苯硫酚（4-ABT）进行了拉曼散射测量。最初，检测到非常微弱的拉曼峰，但当通过NH2基团将银纳米颗粒附着到4-ABT/Cu上时，观察到了明显的拉曼光谱。考虑到当银纳米颗粒吸附在组装在二氧化硅粉末上的4-氨基苯基衍生化硅烷单分子层上时未识别出拉曼峰这一事实，观察到的Ag@4-ABT/Cu的拉曼光谱应该是表面增强拉曼散射（SERS）光谱，它是由银纳米颗粒的局域表面等离子体与铜粉末的表面等离子体激元的电磁耦合产生的。在使用632.8 nm辐射作为激发源的情况下，单个银纳米颗粒附着可实现的额外增强因子估计高达1.4×10(5)。然而，当金纳米颗粒附着到4-ABT/Cu上时，在所有激发波长下获得的拉曼光谱至少弱一个数量级，这表明对于SERS的诱导，金与铜的耦合远不如银与铜的耦合有效。
