Abstract: A series of tabular silver iodobromide microcrystals with different iodide content (3-18 mol%) was prepared (the average size of the microcrystals is about 3 μm and the aspect ratio is about 6:1). The plane distribution of iodide ions was measured semiquantitatively by means of EDS. Using SAM and ion etching, the surface and spatial analyses of iodide ions were carried out. Combining the results of EDS and SAM, the three dimensional iodide ion distribution was obtained. It is found that the iodide content is higher in the center of the microcry-stal than that in the edge. The nearer to the edge, the lower the iodide content. When the value of pAg is high during precipitation of emulsion, the iodide ions added in the early process are transfered to the surface and are enriched on the surface. The structrue of silver iodobromide microcrystals obtained in this condition are not sandwich type.

Key words: silver iodobromide microcrystal, iodide ion, three dimensional distribution, scanning Auger probe, energy disperse spectroscopy