Abstract: A Series of epitaxial octahedral AgCl/AgBr emulsions have been prepared,and the chloride distributions of the epitaxial emulsion grains were measured by employing energydisperse spectroscopy-scanning transmissive electron microscopy(EDS-STEM).It wasfound that the prefered sites in AgCl growing on the host AgBr octahedral are alwaysthe corners,whatever the amount of AgCl is in the epitaxial AgCl/AgBr emulsion。The fluorescence of the AgCl became more abundant in increasing the ratio of AgCl to AgBr,while the emission wavelenthh maintained at 510 nm.The emission of AgBr appeared at 600 nm,no broad-band emission corresponding to AgBrCl was observed.The presenceof minor AgCl in the epitaxial AgCl/AgBr made the photographic sensitivity increasedapparently,nevertheless,high ratio of AgCl to AgBr led to the decrease of photographicsensitivity and fog.

Key words: epitaxial emulsion, chloride distribution, fluorescence photographic sensitivity