Influence of Colour Couplers on the Adsorption of Spectral Sensitizing Agents

The spectral sensitivity of a spectrally sensitized emulsion is in many cases altered by the addition of colour couplers. This alteration is mainly due to a partial desorption of the sensitizing agent. Two possible cases of interaction between the colour coupler and the sensitizer hare been studied.

1.The colour coupler itself is not adsorbed on the surface of the silver halide but forms micelles in the gelatin phase. These micelles act as dissolving agents and desorb the sensitizing agent from the surface of the silver halide crystals. The isotherm, giving the amount of sensitizer solubilised by the colour coupler as a function of the amount still adsorbed on the silver halide crystals, has two different saturation levels.

2.The colour coupler is adsorbed In this case the colour coupler and the sensitizing agent scarcely disturb the adsorption of each other A multilayer adsorption is believed to take place