Characterization of High-efficiency Hypersensitization of AgBr Emulsion by Gold(l) Thiocyanate Solution

Abstract

AbstractPre-exposure treatments of primitive and S-sensitized AgBr emulsion coatings with a gold(I) thiocyanate solution yield, under certain experimental conditions, a large sensitizing effect that cannot be gained by post-exposure subimage latensification. The most critical condition for this high-efficiency Au-hypersensitization is inclusion of a washing step following the gold-bath treatment. The hypersensitizing centre can be identified with small Au clusters on the grain surface, deposited probably through washing-assisted decomplexation of gold(I) thiocyanates followed by disproportionation of Au+ ions. These An clusters may grow to a developable latent image during exposure, thus allowing an unique mode of latent image formation that involves no unstable intermediates. As a result, the lozv intensity failure is eliminated and, if the development condition is strengthened enough, only a single growth event may become sufficient to make a grain developable. Hoivever, the Au-hypersensitization does n...