Mechanistic studies of a new nucleated infectious development system usingpyridinium salts

Photographic properties of 1-benzyl-1,4-dihydronicotinamide (BNAH) are stud ied for better understanding of the mechanism of the production of high con trast by the infectious development which is induced by the combination of a pyridinium salt and Metol-ascorbate developer. Treatment of internally ch emically sensitized silver bromide core/shell emulsion by BNAH and redox bu ffer followed by development gave high internal fog density. It has been su ggested in that the oxidation product of BNAH by redox buffer injects elect rons into the conduction band of silver bromide grains, resulting in the fo rmation of fog centers inside the grains. Results support the hypothesis th at dihydropyridine works as an intermediate in the production of high contr ast by the infectious development in the presence of a pyridinium salt.