An improved emulsion and photographic element

摘要

Improved sensitivity and reduced minimum density are provided by an emulsion in which high bromide tabular grains exhibit an average thickness of less than 0.07 mu m and have latent image forming reduction chemical sensitization sites and adsorbed spectral sensitizing dye on their surfaces. The tabular grains contain a dopant capable of forming shallow electron trapping sites, and the spectral sensitizing dye exhibits an oxidation potential more positive than 1.2 volts. A photographic element is disclosed which locates the emulsion in a layer overlying a minus blue recording emulsion layer. Exceptionally sharp images are formed in the minus blue recording emulsion layer when in the overlying emulsion layer greater than 97 percent of the total projected area of the silver halide grains having an equivalent circular diameter of at least 0.2 mu m is accounted for by tabular grains having an average equivalent circular diameter of at least 0.7 mu m.