Silver halide light sensitive emulsion layer having enhanced photographic sensitivity

摘要

This invention comprises a photographic element comprising a support and at least one silver halide emulsion layer in which the silver halide is sensitized with a compound of the formula: Q-XYwherein Q represents the atoms necessary to form a chromophore comprising an amidinium-ion, a carboxyl-ion or dipolar-amidic chromophoric system when conjugated with XY, and XY is a fragmentable electron donor moiety in which X is an electron donor group and Y is a leaving group other than hydrogen, and wherein: 1) XY has an oxidation potential between 0 and about 1.4 V; 2) the oxidized form of XY undergoes a bond cleavage reaction to give the radical X. and the leaving fragment Y. In a preferred embodiment of the invention, the radical X. has an oxidation potential <-0.7V.