Grain Disorder and its Influence on Emulsion Response

Paper presented at a Symposium on “Fundamental Problems in Photographic Science” organized by the Science Committee of The Royal Photographic Society on 8–13 September 1975 in Oxford, England

Abstract

A study of the influence of grain disorder on the photographic response of an emulsion has been made, based on a collection of silver-bromide emulsions of mean grain area ~1 μm³ and prepared in different ways.

High levels of grain disorder may lead to low sensitivity to normal levels of exposure either by giving rise to competition between surface and internal sites on and within the grains for the products of exposure, or by introducing recombination centres into the grains. An emulsion whose grains are relatively free of gross disorder may also be of low sensitivity to conventional levels of exposure, the low sensitivity in this case arising from dispersity of latent image at the grain surface.

The response of emulsions to heavy exposures IS determined by the level of disorder in their component grains, emulsions of high grain disorder being more susceptible to solarization and the Villard effect than those of low grain disorder. Observations on the Villard effect indicate that grains of high surface sensitivity are those of low internal sensitivity and vice versa. The basic ability of grains to form internal latent-image is determined at the precipitation stage and for the usual type of emulsion is not strongly dependent on the level of chemical sensitization.

Notes

Paper presented at a Symposium on “Fundamental Problems in Photographic Science” organized by the Science Committee of The Royal Photographic Society on 8–13 September 1975 in Oxford, England