Terrace formation of cyanine dye J-aggregates on AgBr microcrystals grown in gelatin

Photosensitizing dyes are required to stretch the sensitivity of silver halides for photographic use to the full wavelength of visible light. The growth of silver halide microcrystals and adsorption of dyes in the form of J-aggregates onto them are performed in gelatin sol. The dye adsorption has been thought to occur homogeneously on every particle of silver halides. However cathodoluminescence microscopy revealed that the quantities of adsorbed dyes on the particles differ significantly. The island growth of dye aggregate layers becomes clear by low-energy high-resolution scanning electron microscopy and atomic force microscopy. The islands align parallel and form a terrace on most particle surfaces ofAgBr. In the area out of the terrace region, there are little dyes in adsorption. The concentration of adsorbed dyes in the terraces on certain particles of AgBr result in a deficiency of the aggregates in adsorption on other particles.