Abstract: The effect of K₄[Ru(CN)₆] dopant on the photographic properties and photoelectronic lifetime of the iodobromide T-grain emulsion was studied in this paper. The results showed that the doping amount, position and distribution of the dopant had effected on photographic properties of the emulsion significantly. The relative sensitivities of the emulsions were remarkable increased when the dopant near to the surface and the core of the grain and decreased when the doping region was near the iodide. The preferred doping amount depends on the doping position, and the optimal relative sensitivity was at the position of 66%—92%.The dopant K₄[Ru(CN)₆] can also prolong the decay time of the free electrons and the shallow-trapped electrons, i.e. prolong their lifetime.

Key words: dope, shallow electron trap, K₄[Ru(CN)₆], iodobromide T-grain emulsion, photoelectronic lifetime