Controlled site epitaxial sensitization of limited iodide silver halide emulsions

Claim 2

A silver halide emulsion comprised of a dispersing medium, silver halide host grains predominantly bounded by {111} crystal faces and containing insufficient iodide to direct silver salt epitaxy to selected surface sites of said grains, and silver salt epitaxially located on and substantially confined to at least one of edge and corner sites of said grains.

Claim 3

A silver halide emulsion according to claim 1 wherein said silver halide host grains exhibit an average aspect ratio of less than 8:1.

Claim 4

A silver halide emulsion according to claim 1 wherein said dispersing medium is a peptizer.

Claim 5

A silver halide emulsion according to claim 3 wherein said peptizer is gelatin or a gelatin derivative.

Claim 6

A silver halide emulsion according to claim 1 wherein said silver halide host grains are comprised of bromide.

Claim 7

A silver halide emulsion according to claim 5 wherein said silver halide host grains are additionally comprised of iodide.

Claim 8

A silver halide emulsion according to claim 6 wherein said silver halide host grains contain less than 10 mole percent iodide.

Claim 9

A silver halide emulsion according to claim 7 wherein said silver halide host grains contain less than 8 mole percent iodide.

Claim 10

A silver halide emulsion according to claim 1 wherein said silver salt is silver halide.

Claim 11

A silver halide emulsion according to claim 9 wherein said silver salt is comprised of silver chloride.

Claim 12

A silver halide emulsion according to claim 1 wherein a site director is adsorbed to said silver halide host grains.

Claim 13

A silver halide emulsion according to claim 11 wherein iodide ions constitute said site director.

Claim 14

A silver halide emulsion according to claim 11 wherein said site director is a spectral sensitizing dye.

Claim 15

A silver halide emulsion according to claim 13 wherein said spectral sensitizing dye is adsorbed to said silver halide host grains in an aggregated form.

Claim 16

A silver halide emulsion according to claim 1 wherein at least one of said silver salt and said silver halide host grains contains a sensitivity modifier incorporated therein.

Claim 17

A silver halide emulsion according to claim 1 wherein said silver salt is epitaxially located on less than half of the surface area provided by said silver halide host grains.

Claim 18

A silver halide emulsion according to claim 16 wherein said silver salt is epitaxially located on less than 25 percent of the surface area provided by said silver halide host grains.

Claim 19

A silver halide emulsion according to claim 17 wherein said silver salt is epitaxially located on less than 10 percent of the surface area provided by said silver halide host grains.

Claim 20

A silver halide emulsion according to claim 1 wherein said silver salt is substantially confined to edge sites on said silver halide host grains.

Claim 21

A silver halide emulsion according to claim 1 wherein said silver salt is substantially confined to corner sites on said silver halide host grains.

Claim 22

A silver halide emulsion according to claim 1 wherein the major crystal faces of said silver halide host grains lie in {111} crystal planes.

Claim 23

A silver halide emulsion comprised of a peptizer, regular octahedral silver halide host grains bounded by {111} major crystal faces and containing less than 15 mole percent iodide, and silver salt epitaxially located on and substantially confined to at least one of edge and corner sites of said grains.

Claim 24

A silver halide emulsion comprised of a peptizer, regular octahedral silver halide host grains bounded by {111} major crystal faces and containing less than 15 mole percent iodide, and silver salt epitaxially located on and substantially confined to at least one of edge and corner sites of said grains.

Claim 25

A silver halide emulsion comprised of a peptizer, silver bromide host grains bounded by {111} major crystal faces, silver chloride epitaxially located on and substantially confined to sites on said host grains chosen from corner and edge sites, and a site director chosen from at least one of iodide ions and spectral sensitizing dye adsorbed to at least those portions of said major crystal faces free of said silver chloride.

Claim 26

A silver halide emulsion comprised of a peptizer, silver bromide host grains bounded by {111} major crystal faces, silver chloride epitaxially located on and substantially confined to sites on said host grains chosen from corner and edge sites, and a site director chosen from at least one of iodide ions and spectral sensitizing dye adsorbed to at least those portions of said major crystal faces free of said silver chloride.

Claim 27

A silver halide emulsion comprised of a peptizer, silver bromoiodide host grains bounded by {111} major crystal faces and containing less than 10 mole percent iodide, silver chloride epitaxially located on and substantially confined to selected surface sites of said host grains chosen from edge and corner sites, and a site director chosen from at least one of iodide ions and spectral sensitizing dye adsorbed to at least those portions of said major crystal faces free of said silver chloride.

Claim 28

A silver halide emulsion comprised of a peptizer, silver bromoiodide host grains bounded by {111} major crystal faces and containing less than 10 mole percent iodide, silver chloride epitaxially located on and substantially confined to selected surface sites of said host grains chosen from edge and corner sites, and a site director chosen from at least one of iodide ions and spectral sensitizing dye adsorbed to at least those portions of said major crystal faces free of said silver chloride.

Claim 29

A silver halide emulsion comprised of gelatin or a gelatin derivative, silver halide host grains bounded by {111} major crystal faces, said halide consisting essentially of bromide and up to 10 mole percent iodide, silver chloride epitaxially located on and substantially confined to at least one of corner and edge sites on said silver halide host grains,and an aggregating spectral sensitizing dye adsorbed to at least those portion of said major crystal faces free of epitaxially located silver chloride.

Claim 30

A silver halide emulsion comprised of gelatin or a gelatin derivative, silver halide host grains bounded by {111} major crystal faces, said halide consisting essentially of bromide and up to 10 mole percent iodide, silver chloride epitaxially located on and substantially confined to at least one of corner and edge sites on said silver halide host grains,and an aggregating spectral sensitizing dye adsorbed to at least those portion of said major crystal faces free of epitaxially located silver chloride.

Claim 31

A silver halide emulsion according to claim 25 wherein said spectral sensitizing dye is present in a concentration of at least 70 percent of the surface area of said host grains.

Claim 32

A silver halide emulsion according to claim 24 wherein said spectral sensitizing dye is an aggregating cyanine or merocyanine dye.

Claim 33

A silver halide emulsion according to claim 27 wherein said spectral sensitizing dye is an aggregating cyanine dye containing at least one nucleus chosen from the group consisting of quinolinium, benzoxazolium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, and naphthoselenazolium nuclei.

Claim 34

A silver halide emulsion according to claim 28 wherein the spectral sensitizing dye is chosen from the group consisting of Anhydro-9-ethyl-3,3'-bis(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyanine hydroxide, Anhydro-5,5'-dichloro-9-ethyl-3,3'-bis(3-sulfobutyl)thiacarbocyanine hydroxide, Anhydro-5,5',6,6'-tetrachloro-1,1'-diethyl-3,3'-bis(3-sulfobutyl)benzimidazolocarbocyanine hydroxide, Anhydro-5,5',6,6'-tetrachloro-1,1',3-triethyl-3'-(3-sulfobutyl)benzimidazolocarbocyanine hydroxide, Anhydro-5-chloro-3,9-diethyl-5'-phenyl-3'-(3-sulfopropyl)oxacarbocyanine hydroxide, Anhydro-5-chloro-3',9-diethyl-5'-phenyl-3-(3-sulfopropyl)oxacarbocyanine hydroxide, Anhydro-5-chloro-9-ethyl-5'-phenyl-3,3'-bis(3-sulfopropyl)oxacarbocyanine hydroxide, Anhydro-9-ethyl-5,5'-diphenyl-3,3'-bis(3-sulfobutyl)oxacarbocyanine hydroxide, Anhydro-5,5'-dichloro-3,3'-bis(3-sulfopropyl)thiacyanine hydroxide, and

Claim 35

1'-Diethyl-2,2'-cyanine p-toluenesulfonate.

Claim 36

1'-Diethyl-2,2'-cyanine p-toluenesulfonate.

Claim 37

In a photographic element comprised of a support and at least one radiation-sensitive emulsion layer, the improvement wherein said emulsion layer is comprised of an emulsion according to any one of claims 1 through 29.

Claim 38

A process of producing a visible photographic image comprising processing in an aqueous alkaline solution in the presence of a developing agent an imagewise exposed photographic element according to claim 30.

Claim 39

A process of preparing a silver halide emulsion comprising providing an emulsion comprised of a dispersing medium and silver halide host grains predominantly bounded by {111} crystal faces and containing insufficient iodide to direct silver salt epitaxy to selected surface sites on the silver halide host grains, adsorbing a site director on the silver halide host grains, and epitaxially depositing a silver salt on the silver halide host grains and substantially confining epitaxial deposition to at least one of edge and corner sites on the silver halide grains.

Claim 40

A process of preparing a silver halide emulsion comprising providing an emulsion comprised of a dispersing medium and silver halide host grains predominantly bounded by {111} crystal faces and containing insufficient iodide to direct silver salt epitaxy to selected surface sites on the silver halide host grains, adsorbing a site director on the silver halide host grains, and epitaxially depositing a silver salt on the silver halide host grains and substantially confining epitaxial deposition to at least one of edge and corner sites on the silver halide grains.

Claim 41

A process according to claim 32 wherein the silver halide host grains are selected to have an average aspect ratio of less than 8:1.

Claim 42

A process according to claim 32 wherein the halide of the silver halide host grains is chosen to consist essentially of bromide.

Claim 43

A process according to claim 32 wherein the halide of the silver halide host grains is chosen to consist essentially of bromide and less than 10 mole percent iodide.

Claim 44

A process according to claim 32 wherein the halide of the silver halide host grains is chosen to consist essentially of bromide and less than 8 mole percent iodide.

Claim 45

A process according to claim 32 wherein the site director is comprised of iodide ions.

Claim 46

A process according to claim 32 wherein the site director is comprised of a spectral sensitizing dye.

Claim 47

A process according to claim 38 wherein the spectral sensitizing dye is selected from among aggregating cyanine and merocyanine dyes.

Claim 48

A process according to claim 39 wherein the spectral sensitizing dye is selected from among J-aggregating cyanine dyes.