Abstract: The effect of six phenylhydrazides (general formula: R-Ph-NH-NH-COR’) on the photographic characteristics of silver halide emulsion has been studied.The results show that there are relations between the effect of infectious development and the structure of phenylhydrazides.Additionally, the effect and mechanism of contrast-promoting agents (alcohols and amine derivatives) has been investigated in detail.The fact indicates that it can not only eliminate the feed back inhibition effect which is caused by the use of phenylhydrazide alone, but also accelerate the infectious development greatly and enhance the contrast and speed of photographic development when a little amount of contrast-promoting agent is added in PQ developer.Furthermore, the mechanism of infectious development and contrast-promoting action is explained more definitely on the basis of analyzing the reduction rection products and intermediates of phenylhydrazides by means of LC, GC-MS and ESR spectrometry.

Key words: infectious development, phenylhydrazide, contrast-promoting agent