Electron-Microscopic Observation of Photographic Emulsion. I : Appearance of the "Halos" in Electron Micrographs

Using emulsion of "Fuji" process photographic plate and emulsion produced by the ripening of colloidal silver bromide, the "halos" in electron micrographs were observed under various conditions. It was found that (1) the "halos" appeared with intense electron bombardment, (2) this was more remarkable in the case of using the emulsions before sensitization produced in the dark room than that after sensitization, (3) the ring pattern was clearer in the case of suddenly increasing an electron beam density than the case of slowly increasing it, and (4) the appearance of the "halos" depended on the thickness of gelatine and it appeared only in the case of proper thickness of gelatine. The cause of the "halos" was discussed and a model experiment was carried out to confirm the physical consideration obtained