Abstract: Using AgBr single crystal and cyanine dyes as substrate and spectral sensitizers respectively, the photocurrent pf AgBr was investigated in this paper. It was shown that the photo-induced absorption band can be observed when AgBr was irradiated in its intrinsic absorption range. The crystal presents self-sensitized photoconductivity in its nonintrinsic absorption band when it was exposed to the light in the induced absorption band. Both cathodic and anodic photocurrent of AgBr were sensitized by adsorbed cyanine dyes, therefore, the observed photo-current may include the self-sensitized photocurrent. On the basis of our experiments, a criterion for the sensitizing (or desensitizing) ability of cyanine dyes, S_D, was proposed. It may be more comprehensive than other known criteria. By means of the S_D-λ curves obtained, a prediction on the ability of spectral sensitization of dyes can be made. A set of practical dyes and their combinations were analysed with the S_D criterion in this work.

Key words: silver bromide crystal, spectral sensitizing photocurrent, spectral sensitizing dyes, criterion for sensitizing ability