NUCLEATION AND GROWTH OF CYANINE DYE J-AGGREGATES ON AGBR EMULSION CRYSTALS STUDIED BY ANALYTICAL COLOR FLUORESCENCE ELECTRON-MICROSCOPY

Cathodoluminescence images of lfopropyl-5,6,5',6'-dibenz-9-ethyl-oxaca rbocyanine J-aggregates adsorbed on (100) surfaces of practical emulsi on AgBr microcrystals were used to study nucleation, preferential adso rption, and growth. Nucleation of J-aggregates occurred when dye molec ules were added to gelatin sols of AgBr microcrystals and the aggregat e nuclei adsorbed to the surface of AgBr. Residual dyes in the solutio n worked to increase the size of existing aggregate nuclei on the surf ace and did not contribute nucleation of new aggregates. The temperatu re rise of solutions during aging led to normal size distribution of J -aggregates, suggesting that there is a most stable size of J-aggregat es for given growing conditions. The surface selectivity of J-aggregat es on adsorption was checked by comparing J-aggregation on AgBr cubes, octahedra, and cuboctahedra.