Electronic Properties of Chemically Produced Silver Clusters: Photobleaching Studies

Abstract

Chemically produced silver clusters lead to a 476 nm peak in the diffuse reflectance spectra (DRS) of AgBr emulsions. Earlier photobleaching studies have shown that this peak can be resolved into two component peaks—one at 474 nm which photobleaches, and a less intense one at 482 nm that does not. The 474 nm peak has been assigned to hole removing silver clusters. This interpretation has been questioned since photoproduced silver clusters, which are obviously electron trapping, are also known to photobleach (solarization). This possibility was examined with photoproduced silver clusters and photobleach conditions which were identical to those used for the earlier photobleach study. Such clusters are found to photobleach, but not to the extent that would explain the observed photobleaching of the 474 nm DRS peak. In the presence of a modest amount of hole removing silver clusters provided by reduction sensitization, the photoproduced silver clusters underwent minimal photobleaching. These results support the earlier assignment of the 474 nm DRS peak to hole removing silver clusters.