Doping Leads to More Efficient Film

A team from the Université Paris-Sud in Orsay, France, and Agfa-Gevaert NV in Mortsel, Belgium, has reported that formate ions enhance the efficiency of silver halide crystals nearly to their theoretical limit. The development, which, unlike reduction sensitization does not significantly increase fogging, promises to improve the performance of photographic film.

The researchers coated 0.37-µm-diameter microcrystals of AgBr with a 25-nm-thick shell of HCO₂Ag and exposed an emulsion of the grains with 410-nm light. Diffuse reflectance, fluorometric and sensitometric analyses revealed that only 2 ±0.3 photons per crystal would make half of the grains developable vs. 20 ±3 photons per crystal in typical emulsions.