Abstract: A process of preparing a photographically useful high chloride {100} tabular grain emulsion is disclosed. The grain characteristics of the emulsion are improved by interrupting precipitation of the grain nuclei used to prepare the emulsion by performing a halide conversion step in which a molar ratio of iodide ion to bromide ion in the range of from 1.times.10.sup.-4 :1 to 5.times.10.sup.-2 :1 is employed.

Abstract: A process is disclosed of precipitating high chloride {100 } tabular grain emulsions having an average tabular grain thickness of less than 0.3 micrometer. Higher average grain equivalent circular diameters and aspect ratios are realized by employing a gelatino-peptizer during at least a portion of the precipitation that satisfies the formula:(Pro+Hypro).div.(Ser+Thr)=<4.0wherein Pro, Hypro, Ser and Thr represent the proline, hydroxyproline, serine, and threonine amino acid components, respectively, of the gelatino-peptizer. When the formula satisfying gelatino-peptizer is present during grain nucleation and contains at least 40 micromoles of methionine per gram of gelatino-peptizer, the high chloride {100} tabular grains account for a high proportion of total grain projected area. When the formula satisfying gelatino-peptizer is present during grain growth and contains <4 micromoles of methionine per gram of gelatino-peptizer, the time required to prepare the emulsion is reduced.

Abstract: Photographically useful radiation-sensitive high chloride {100} tabular grain emulsions containing iodide are disclosed. A high proportion of the {100} tabular grains contain crystal lattice dislocations extending inwardly from their peripheral edges. The dislocations are created by introducing elemental iodine into a high chloride {100} tabular grain emulsion, reducing the iodine to iodide, displacing chloride ions at the peripheral edges of the tabular grains with iodide ions, and then continuing growth of the high chloride {100} tabular grains. The dislocations in the peripheral and, particularly, corner regions of the tabular grains increase their sensitivity.

Abstract: A process is disclosed for preparing high chloride {100} tabular grain emulsions containing crystal lattice dislocations in peripheral regions of the tabular grains. In the initial step of the process a radiation-sensitive high chloride {100} tabular grain emulsion is produced to provide host grains. Lateral growth lateral growth of the {100} major surfaces of the tabular grains is extended by precipitating a high chloride peripheral region onto the host tabular grains. After the host grains have been provided an iodide ion source compound with a maximum second order reaction rate constant within the dispersing medium of less than 1.times.10.sup.3 mole.sup.-1 sec.sup.-1 is introduced into the host emulsion to release iodide ions for incorporation into the tabular grains at their peripheral edges by chloride ion displacement. In the resulting emulsion 10 or more crystal lattice dislocations extending inwardly from the peripheral edges of the {100} tabular grains are observed.

Abstract: A process is disclosed of precipitating a high chloride {100} tabular grain photographic emulsion in which iodide incorporation in previously formed grain nuclei is relied upon to create the crystal lattice defects responsible for tabular grain growth. Undesirable dilution of the emulsion is avoided by replacing soluble iodide salt solution addition with iodine solution addition, allowing the volume of the iodine solution to be limited to less than 10 percent of the emulsion volume at the conclusion of tabular grain growth.

Abstract: A radiation-sensitive high bromide {111 } tabular grain emulsion is disclosed containing a dispersing medium including a peptizer adsorbed to the tabular grains. The peptizer is a polymeric hydrophilic colloid containing repeating units derived from a diallylammonium monomer.

Abstract: A process is disclosed of preparing a photographically useful emulsion containing radiation-sensitive silver iodohalide grains. Silver halide grains having a face centered cubic rock salt crystal lattice structure are precipitated within an aqueous dispersing medium including a hydrophilic colloid peptizer. Iodide ion is introduced into the crystal lattice structure by introducing elemental iodine into the dispersing medium and maintaining the dispersing medium within a pH range of from 5 to 8.