Surface-Dye Concentration Relationships in Sensitized Photographic Emulsions

Abstract

A study has been made of the relationship between the total surface of silver halide in a photographic emulsion and the concentration of sensitizing dye necessary to produce maximum sensitizing. It was found that the amount of dye producing maximum sensitizing is directly proportional to the silver halide surface. Approximate calculations indicate that at optimum sensitizing concentration, the sensitizing dye is adsorbed to the silver halide grains in a monomolecular layer.

THE ACTION OF OPTICAL SENSITIZERS ON THE PHOTOGRAPHIC PLATE1

“…This desensitizing effect of sensitizing dyes when used in larger concentrations seems to be of a general nature. A very extensive and careful recent investigation by Leermakers, Carroll, and Staud (27) showed invariably the same result.…”

Desensitization by Sensitizing Dyes

“…The results of exposure through a Wratten No. 47 filter are plotted in figure 11 on a linear scale, along with the data of Leermakers, Carroll, and Stand (9). In figure 12, values of l/2J«o for the same coatings are plotted against concentration: these show that desensitization can be measured at the lowest concentrations of dye.…”

“…Earlier data from these Laboratories had indicated that desensitization by practically useful dyes was associated primarily with the use of excessive concentrations. Leermakers, Carroll, and Stand (9) have given examples of the change in sensitivity to light transmitted by the standard tricolor filters, corresponding to varying concentrations of dye. Sensitivity to exposure through the red and green filters passed through well-defined maxima as the concentration was increased; sensitivity to light transmitted by the blue filter remained practically constant for all concentrations up to the value corresponding to the red and green maxima, and then decreased rapidly.…”