CYANINE DYE AGGREGATES ON AGBR EMULSION CRYSTALS STUDIED BY ANALYTICAL COLOR FLUORESCENCE ELECTRON-MICROSCOPY .2. THE MORPHOLOGY OF J-AGGREGATES AND CHANGE OF LUMINESCENCE COLOR CAUSED BY ELECTRON-IRRADIATION

J-aggregates of fopropyl-5,6,5',6'-dibenzo-9-ethyl-oxacarbocyanine tri ethyl ammonium salt and of 1,1'-diethyl-2,2'-cyanine iodide were grown and adsorbed at 60-degrees-C on silver bromide cuboctahedral microcry stals in gelatin. The size and orientation of J-aggregates were measur ed on (100) and (111) surfaces of cuboctahedral AgBr from cathodolumin escence micrographs taken in the scanning electron microscope. Though these dyes have been believed to adsorb preferentially on either (100) or (111) surfaces, luminescence was detected from both dyes on both ( 100) and (111) surfaces of cuboctahedral AgBr. This observation sugges ted that the nucleation of J-aggregates occurred not on the surface, b ut in the solution, and that after the adsorption of nuclei onto the s urface the aggregates continued to grow with a supply of dye molecules from solution. The luminescence color revealed changes of electronic states of J-aggregates between those ''unexposed'' and ''exposed'' by the electron beam during observation.