紫膜表面增强共振拉曼散射谱的研究

本文报道紫膜在银胶上的表面增强共振拉曼散射与时间延迟、pH值的关系以及吸附对紫膜光化学循环的影响。在弱酸性pH条件下,紫膜和银胶混合3小时后才能看到分子—金属振动谱带。增强效应随pH值降低而加大,在pH3.8附近变化最明显。用488nm线激发。能分辨紫膜的M412和其他光化学循环中间体。pH3.8,M412的1567cm~(-1)特征振动带作为峰肩出现在变宽了的1536cm~(-1)带上,表明紫膜吸附在金属表面上并不阻断其光化学循环。pH2.7时,1567cm~(-1)带变得不明显,可能是M412的形成受到低pH值的限制。

STUDIES ON SURFACE ENHANCED RESONACE RAMAN SPECTRA OF PURPLE MEMBRANE

The dependence of the surface enhanced resonace Raman scattering with silver hydrosols on time delay and defferent pH values of purple membrane and the effect of absorption on its photochemical cycle are reported. Under the weak acid, no significant enhancement was observed until the purple membrane was mixed with hydrosols after 3 hours. The enhancement was increased as pH value decreased. The most remarkable enhancement occured near pH 3.8 with 488nm line for excitation, a characteristic 1567cm~(-1) vibration band which arises from the photochemical cycle intermediate M412 of purple membrane was able to be resolved from others. This band as a shoulder on the widening 1536cm~(-1) band at pH 3.8 shows that adsorption of purple membrane on the metal surface does not interupt its photochemical cycle. Meanwhile, 1567cm~(-1) band was unmarkable at pH 2.7. It suggests that formation of M412 is restrieted under the lower pH.