TABULAR GRAIN EMULSIONS WITH SELECTED SITE HALIDE CONVERSIONS AND PROCESSES FOR THEIR PREPARATION

摘要

A radiation-sensitive photographic emulsion is disclosed containing a gelatino-vehicle and tabular grains accounting for at least 70 percent of total grain projected area comprised of at least 90 mole percent bromide and up to 12 mole percent iodide, based on total silver, having {111} major faces that form corners joined by linear edges, and containing halide conversion dislocations that are confined to corner regions. Superior performance and selected site halide conversion can be realized by maintaining a pBr of less than 3.5 and by employing for halide conversion an iodide ion source exhibiting a second order reaction rate constant with the gelatino-vehicle of less than 10<-3> mole<-1> sec<-1>.