半导体纳米粒子在反胶束中的合成及其与芘分子间的跨相电子转移  

SYNTHESIS OF SEMICONDUCTOR NANOPARTICLES IN REVERSE MICELLES AND MICROHETEROGENEOUS ELECTRON-TRANSFER FROM PYRENE TO THESE PARTICLES

作　　者：臧泠[1] 刘春艳[1] 赵进才[1] 任新民[1] 沈涛[1] 

机构地区：[1]中国科学院感光化学研究所

出　　处：《感光科学与光化学》1996年第4期331-340,共10页Photographic Science and Photochemistry

摘　　要：本文在ＡＯＴ／异辛烷反胶束中合成了ＣｄＳ和ＺｎＳ半导体纳米粒子．粒子的荧光量子产率随胶束水含量的增大而减小．这可以归结为水含量增大导致胶粒表面Ｃｄ^（２＋）或Ｚｎ^（２＋）离子浓度降低，因为这两种离子在胶粒表面富集有利于形成硫空位，从而增大光生电子－空穴对的发光复合．研究发现，Ａｇ~＋离子可以有效猝灭ＣｄＳ和ＺｎＳ纳米粒子的荧光发射，该猝灭过程可以用Ａｇ~＋离子在胶束中的Ｐｏｉｓｓｏｎ分布来描述．以溶解在有机相中的ｐｙｒｅｎｅ作电子给体，在光激发下可以向ＣｄＳ粒子注入电子，而和ＺｎＳ粒子间没有电荷转移发生，这可以解释为两种半导体的导带边相对于ｐｙｒｅｎｅ激发态氧化电位所处的位置不同。Ｃｕ^（２＋）或Ａｇ~＋离子在ＺｎＳ颗粒表面吸附，可以形成Ｃｕ_ｘＺｎ_（１－ｘ）Ｓ或Ａｇ_（２ｘ）Ｚｎ_（１－ｘ）Ｓ复合粒子，降低ＺｎＳ粒子的导带位置，从而使之能够接受来自ｐｙｒｅｎｅ激发态的电子．实验结果证实了这种论点．Semiconductor nanoparticles of CdS and ZnS have been synthesized in AOT-isooctane reverse micelles. It was found that the fluorescence quantum efficiency of the semiconductor particle decreases with increasing water content. This is attributed to the dilution of Cd￣(2+) or Zn￣(2+) ions at the interface of semiconductor particles. These cations favor the formation of sulfur vacancy, where the radiation recombination of the electron-hole pair occurs. The fluorescences of CdS and ZnS particles are effectively quenched by the addition of Ag￣+ ions.Such a process can be described by the Poisson statistics for the distribution of AG+ ions in reverse micelles. An efficient microheterogeneous electron-transfer was observed from pyrene to the CdS particles formed in AOT-isooctane reverse micelles,whereas no electrontransfer can be observed at ZnS particles. This is explained with considering the relative positions of the conduction bands of CdS and ZnS particles with respect to the oxidation potential of the excited singlet of pyrene. Adsorption of Cu￣(2+) and Ag￣+ ions on the ZnS particle leads to the formation of mixed semiconductor particles, Cu_x-Zn_(1-x)S and Ag_(2x)Zn_(1-x)S, the conduction bands of which are adjusted between those of ZnS and CuS or Ag_2S. Electrons can be injected from pyrene to these mixed particles. The efficiency of the electron-transfer is determined by the probability of the contact of pyrene with the semiconductor particles.

关 键 词：半导体 纳米粒子 反胶束 电子转移 芘 

分 类 号：O472.3[理学—半导体物理]