Abstract: The sensitization of AgCl emulsion by hydroxy-tetraazaindene and the relationship between photographic properties of the emulsion and its spectral absorbance have been investigated. The results indicated that sensitivity of spectral-sensitized emulsion could be increased by hydroxy-tetraazaindene, namely, supersensitization take place, and at the same time,fog of emulsion also be inhibited. It is also found that the adding order of dye and hydroxytetraazaindene has exceedingly effect on the photographic property. By the reflection spectra and the ESR experiment, it is suggested that there is relationship between sensitivity of emulsion and the formation of aggregate of dye on the emulsion grains and the amount of light induced dye positive hole.

Key words: hydroxy-tetraazaindene, AgCl emulsion, supersensitization