Mechanism of Sensitization of Silver Bromide lodide Emulsions by Hexachloroiridate (IV)

Abstract

Silver bromide iodide emulsions with varying content of Agl were sensitized by L(NH4)21rC16(1), and the degree of surface sensitization increased with increasing ratio of intetnal/Surfape speeds of the primitive emulsions. (1) increased the surface speeds, and decreased the internal speeds of both cubic and octahedral AgBr grains. These phenomena caused by (1) were similar to those by sulfur sensitization. The degree of sensitization by (1) was the largest for the grains which were not sulfur-sensitized, decreased with increasing degree of sulfur sensitization, and at last became negligible. Since it is believed that sulfur sensitization increases photographic speeds by providing electron traps, it is suggested that (1) increases photographic speeds also by providing electron traps.