還元増感の機構に対する考察

抄録

A detailed review is made for the mechanism of reduction sensitization. Experimental results with regard to it are summarized, that is, it increases both surface and internal sensitivity, does not decrease photoconductivity, and depresses low intensity reciprocity failure, action of it does not compete sulfur sensitization or phenosafranine, and its specks are destroyed by exposure. They seem to suggest that reduction sensitization specks act as hole traps. It is also shown that opposite phenomena exist especially at high level of sensitization, that is, decrease of internal sensitivity and photoconductivity. Presence of two kinds of reduction sensitization specks, acting as electron traps and hole traps, is considered. Discussions about a difference between them are introduces. One hypothesis for the difference is the size and the other is the electric charge. At the former, small specks are hole traps and large specks are electron traps. At the latter, positively charged specks are electron traps and negatively charged or neutral specks are hole traps. It is suggested that at small specks difference of charge determines those properties but at large specks this difference does not become important and they mainly act as electron traps. It is also emphasized that hole trapping and halogen accepting are different action and the destruction of reduction sensitization specks by exposure is a phenomenon of solarization.