苯甲酸、邻羟基苯甲酸和对羟基苯甲酸在银胶粒中的表面增强喇曼散射

在银胶体中进行了苯甲酸、邻羟基苯甲酸(又名水扬酸)和对羟基苯甲酸的表面增强喇曼散射。得到并分析了这三种分子的增强喇曼谱。这三个分子都含有ν(C—CO₂^-)伸缩振动。水扬酸和对羟基苯甲酸是同分异构体,都含有ν(C—OH)伸缩振动,但处于不同位置上。借此我们分析了相对于表面不同距离和不同取向下的增强因子变化,并与纯电磁理论的球形颗粒模型进行了比较。发现了明显的分歧,讨论了可能的原因。还讨论了凝聚对增强因子的影响,并提出了控制胶体凝聚的可能途径。 关键词：

SURFACE ENHANCED RAMAN SCATTERING FROM BENZOIC ACID, SALICYLIC ACID AND P-HYDROXYBENZOIC ACID IN Ag COLLOIDS

We studied surface enhanced Raman scattering (SERS) from Benzoic Acid (BA), Salicylic Acid (SA) and P-Hydroxybenzoic Acid (PHBA) in silver sols. The enhanced Raman spectra are recorded and analyzed. The three molecules all contain vibration of ν(C-CO₂^-) and two of them (SA and PHBA) contain vibration of ν(C-OH), but located at different position. Making use of this situation, we analyzed the dependance of enhancement factor on the distance and orientation of the vibration dipoles relative to the surface and also compared with the pure electromagnetic model for SERS. An apparent discrepancy were revealed. The possible origins are disscussed. We also discussed the influence of coagulation of silver particles on the enhancement factors and pointed out the way for optimizing the enhancement in silver colloid.