Cyril J. Staud

Spectral Sensitivity and Light Absorption of Dye‐Sensitized Photographic Emulsions

Direct measurements on emulsions sensitized with certain cyanine dyes show a correspondence between the shapes of the light absorption and sensitivity curves in the region of color sensitizing. It was found that the absorption curves of silver bromide dyed with some cyanine dyes are essentially the same as the absorption curves of the dyes in saturated inorganic salt solutions. It is postulated that there are two types of adsorption of cyanine dyes to silver bromide, aggregated and molecular. An emulsion sensitized with a cyanine dye under proper conditions can show sensitivity in different spectral regions, corresponding to the light absorption characteristics of dye adsorbed in the aggregated and molecular states.

Surface‐Dye Concentration Relationships in Sensitized Photographic Emulsions

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.