| 摘要 |
PURPOSE:To improve reciprocity law failure characteristics in low illuminance by incorporating a specified amt. of at least one kind of water-soluble iridium compd. CONSTITUTION:A silver halide emulsion is obtained by physically ripening a silver halide emulsion in the presence of ammonia and a water-soluble iridium compd. in an amt. of 10<-3>-10<-5> mol per mol silver halide at a pH of 7-9. A preferable acid added for controlling rise of pH is acetic, sulfuric, nitric, or the like acid, and a concn. of ammonium ions in the soln. is 0.005-1.5mol/l, preferably, in the form of an aq. ammonia, and as the water-soluble iridium compd., a hexahalogeno complex salt, such as hexachloro-Ir(III) acid salt, Ir(III), and (IV) chloride are usable, and it is added, preferably, before the end of growth of silver halide, into a physical ripening reaction vessel. |
