吸附在溴化银颗粒表面上的增感染料的ESR波谱研究

本文用电子顺磁共振技术研究了光照条件下三十八种增感染料与溴化银之间发生的电子转移过程。增感染料和溴化银无论在黑暗处还是在光照下,均不产生ESR信号。当增感染料吸附在溴化银颗粒表面上时,如不加光照,仍看不到ESR信号。只有在光照条件下,才有可能观察到ESR信号,这主要取决于增感染料分子的最高占有能级与溴化银价带的相对位置。若染料分子的最高占有能级比溴化银价带顶部高0.7 eV,就可以观察到ESR信号,反之则观察不到。顺磁性中心是由染料正空穴Dye^©形成的。根据ESR信号的强度可以判断增感染料是否有较强的减感作用。

ESR SPECTRA OF SENSITIZING DYES ABSORBED ON THE SURFACES OF AgBr GRAINS

Electron transfer processes between sensitizing dyes and AgBr grains were studied by ESR technique. Neither sensitizing dyes nor AgBr grians under exposure to light gave ESR signal. The AgBr grains absorbing dyes gave no signal in the dark. The ESR signals were observed for the dyes whose highest occupied levels were 0.7 eV higher than the top of the valence band of AgBr. Paramagnetic centre was formed by the positive hole of dyes (Dye^©). The stronger the dye shows its ESR signal the more it desensitizes AgBr crystals.