DO INTERNAL-IMAGE CENTERS IN AgBr EMULSIONS TRAP HOLES OR ELECTRONS?

We have made two-exposure experiments on coatings of two AgBr emulsions that exhibit both surface and internal sensitivity. One emulsion contained monodisperse cubic grains and the other monodisperse octahedral grains. If the coatings were bleached in a ferricyanide solution after the first exposure, the grains were desensitized to the second exposure. The exposures were 10** minus **3 and 10 sec, in any combination. Our conclusion is that the internal image and subimage left after the first exposure and subsequent bleaching provide electron-trapping centers that compete with the surface electron-trapping centers during the second exposure.