US3411914A - Method for stabilizing x-ray emulsions to red safelights - Google Patents

Method for stabilizing x-ray emulsions to red safelights Download PDF

Info

Publication number
US3411914A
US3411914A US382407A US38240764A US3411914A US 3411914 A US3411914 A US 3411914A US 382407 A US382407 A US 382407A US 38240764 A US38240764 A US 38240764A US 3411914 A US3411914 A US 3411914A
Authority
US
United States
Prior art keywords
emulsion
salt
tetrazaindene
emulsions
red
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US382407A
Inventor
Dostes Claude
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Application granted granted Critical
Publication of US3411914A publication Critical patent/US3411914A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/34—Fog-inhibitors; Stabilisers; Agents inhibiting latent image regression
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/08—Sensitivity-increasing substances
    • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising

Definitions

  • This invention relates to photographic emulsions, and more particularly to photographic emulsions containing tetrazaindene antifoggants, which emulsions are not fogged by red safelights.
  • One object of my invention is to provide photographic emulsions containing terazaindene salts, which emulsions are substantially insensitive to commonly employed red safelights.
  • Another object of my invention is to provide a method of preparing photographic emulsions containing tetrazaindene salts, which emulsions are substantially insensitive to red radiation such as that emitted by commonly employed photographic red safelights.
  • Other objects of my invention will appear herein.
  • the preparation of silver halide emulsions involves three separate operations: (1) the emulsification and digestion or ripening of the silver halide; (2) the freeing of the emulsion from aqueous soluble salts usually by washing; and (3) the second digestion or after-ripening to obtain increased sensitivity (Mees, The Theory of the Photographic Process, 1954, p. 4).
  • the noble metal salt and tetrazaindene salt are incorporated in the emulsion subsequent to the afterripening step or second digestion. In order to obtain satisfactory results, it is necessary to first add the tetrazaindene salt to the emulsion, and then the noble metal salt, followed by a short period of digestion.
  • EXAMPLE I A coarse grain silver bromoiodide emulsion of the type used in medical X-ray films was prepared in the customary manner, sulfur sensitized in accordance with Sheppard U.S. Patent 2,410,689, and after the second digestion, while the emulsion was cooling at a temperature of about 50 C., 1 gram 4-hydroxy-6-methyl-1,3,3a,7- tetrazaindene sodium salt per mole silver was incorporated in the emulsion, and immediately thereafter 1.3 mg. potassium chloroaurate per mole of silver was added to the emulsion. The temperature of the emulsion was held at about 50 C. for about 10 minutes, and then allowed to cool.
  • the emulsion was coated on a support and subjected to radiation from a commonly used red safelight.
  • the emulsion was found to be essentially free from fog whereas a control emulsion, which was the same as the test emulsion except that the noble metal salt was added before the tetrazaindene salt, was badly fogged when tested in the same manner.
  • the emulsion in accordance with the invention possessed good sensitivity to X-ray intensifying screen radiation.
  • the addition of the salts in accordance with the invention does not modify the sensitivity of the emulsion to X-ray radiation.
  • I may use any of the tetrazaindene salts which are antifoggants for silver halide emulsions and which impart red sensitivity to the emulsion, for example, those described by Carroll et al. U.S. Patent 2,716,062 or Tinker et al. U.S. Patent 2,835,- 581, in the form of their alkali metal or ammonium salts.
  • Particularly suitable are the 4-oxo or 4-hydroxytetrazaindenes, e.g., salts of the 4-hydroxy-l,3,3a,7- tetrazaindenes.
  • tetrazaindenes may contain various substituents, such as hydroxy, alkyl, amino and carboxyl.
  • the salts may be conveniently prepared, for example, by reacting hydroxyl or carboxyl containing tetrazaindenes with an alkali metal hydroxide.
  • the tetrazaindene salt may be employed in amounts of from 0.25 to 10, and preferably 1.0 to 5.0 g. per mole of silver.
  • the noble metal salts which are employed are water soluble, although insoluble noble metal salts may be used.
  • Representative salts of the noble rnetals, such as ruthenium, rhodium, palladium, iridium and platinum, which may be used include ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite.
  • a soluble gold salt is used, potassium chloroaurate being particularly suitable.
  • Other representative useful gold salts include potassium aurithiocyanate, auric trichloride and 2-aurosulfobenzothiazole methochloride.
  • the noble metal salts are preferably employed in amounts of 1.0 to 5.0 mg. per mole of silver, although the most useful range is 0.25 to 10 mg. per mole of silver.
  • a noble metal salt may also be added to the emulsion before the after-ripening to increase sensitivity; advantageously, a gold salt is employed.
  • other sensitizers may be used with the gold (or noble metal) salts if desired, such as sulfur sensitizers, for example, those described in Sheppard et al. U.S. Patents 1,574,944, 1,623,- 499 and 2,410,689.
  • the tetrazaindene salt is added to the emulsion first and then the noble metal salt is incorporated therein.
  • the salts must be added to the emulsion at the earliest, at the end of the after-ripening or second digestion, or anytime thereafter. It is necessary to add the tetrazaindene salt subsequent to the after-ripening step in the emulsion preparation since such salts would inhibit the effect of chemical sensitizers it added at an earlier stage of the emulsion preparation.
  • the addition of the tetrazaindene and noble metal salts is followed by a short period of digestion of the emulsion, such as from about 1-10 minutes at about 50 C.
  • the salts are added during cooling of the emulsion after the second digestion, and while the emulsion is at about 50 C.
  • the invention is applicable to emulsions containing tetrazaindene salt antifoggants, which emulsions are not spectrally sensitized, or are spectrally sensitized only to the green region of the spectrum.
  • the invention is particularly useful with medical X-ray emulsions which are not spectrally sensitized, but which may, of course, be chemically sensitized.
  • Emulsions in accordance with the invention have good fog stability and are substantially insensitive to the conventional red safelights employed in the photographic industry.
  • Such safelights may be prepared, for example, by covering a 15 or 25 watt tungsten bulb with a filter which transmits light substantially only in the red region of the spectrum.
  • An improved method defined by claim 1 further comprising a step of digesting the emulsion for a short time following the defined additions of tetrazaindene and noble metal salts.
  • a method defined by claim 1 wherein the defined tetrazaindene salt is an alkali metal salt of a 4-hydroXy-1,3, 3a,7-tetrazaindene and the defined noble metal salt is a water-soluble gold salt.
  • a method of preparing photographic silver halide X-ray emulsions containing tetrazaindene salt antifoggant which method comprises the steps of emulsification, removal of soluble salts and after-ripening, the improvement which comprises first adding to the emulsion, while it is cooling subsequent to the after-ripening step, at about C., about 1 g. per mole silver of 4-hydroxy-6-methyl- 1,3,3a,7-tetrazaindene sodium salt, and following said first addition adding to the emulsion about 1.3 mg. per mole silver of potassium chloroaurate.

Landscapes

  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

Description

United States Patent 3,411,914 METHOD FOR STABILIZING X-RAY EMULSIONS TO RED SAFELIGHTS Claude Dostes, Joinville-le-Pont, France, assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed July 13, 1964, Ser. No. 382,407 Claims priority, application France, Dec. 5, 1963, 956,168 6 Claims. (Cl. 96-101) ABSTRACT OF THE DISCLOSURE Photographic silver halide emulsions are prepared by adding, after the end of the after-ripening step, first a tetrazaindene salt and then a noble metal salt. These emulsions have good sensitivity to image-forming radiation shuch as X-ray intensifier screen emissions and are substantially insensitive to red safelights.
This invention relates to photographic emulsions, and more particularly to photographic emulsions containing tetrazaindene antifoggants, which emulsions are not fogged by red safelights.
It is known to incorporate various tetrazaindene compounds, such as tetrazaindene salts, in photographic emulsions as antifoggants. While these compounds provide lgood fog control, they absorb some red radiation causing fog in the emulsion when handled in the pres ence of conventional red safelights. It therefore appears desirable to provide emulsions containing tetrazaindene salt antifoggants, which emulsions are not fogged by red radiation such as that emitted from red safelights.
One object of my invention is to provide photographic emulsions containing terazaindene salts, which emulsions are substantially insensitive to commonly employed red safelights. Another object of my invention is to provide a method of preparing photographic emulsions containing tetrazaindene salts, which emulsions are substantially insensitive to red radiation such as that emitted by commonly employed photographic red safelights. Other objects of my invention will appear herein.
These and other objects of my invention are accomplished by providing photographic emulsions which contain a noble metal salt and a tetrazaindene salt which is an antifoggant for photographic silver halide emulsions.
The preparation of silver halide emulsions involves three separate operations: (1) the emulsification and digestion or ripening of the silver halide; (2) the freeing of the emulsion from aqueous soluble salts usually by washing; and (3) the second digestion or after-ripening to obtain increased sensitivity (Mees, The Theory of the Photographic Process, 1954, p. 4). In accordance with my invention, the noble metal salt and tetrazaindene salt are incorporated in the emulsion subsequent to the afterripening step or second digestion. In order to obtain satisfactory results, it is necessary to first add the tetrazaindene salt to the emulsion, and then the noble metal salt, followed by a short period of digestion.
The addition of only a gold salt (or noble metal) salt to an emulsion at the end of the after-ripening step, or thereafter, lowers the sensitivity of the emulsion to red radiation, but causes an undesirable desensitization of the emulsion to image-forming radiation. However, the addition of tetrazaindene salt and noble metal salt in that order subsequent to after-ripening of an emulsion provides an emulsion having good sensitivity to image-forming radiation and which is substantially insensitive to red radiation.
My invention will be further illustrated by the following example.
ice
EXAMPLE I A coarse grain silver bromoiodide emulsion of the type used in medical X-ray films was prepared in the customary manner, sulfur sensitized in accordance with Sheppard U.S. Patent 2,410,689, and after the second digestion, while the emulsion was cooling at a temperature of about 50 C., 1 gram 4-hydroxy-6-methyl-1,3,3a,7- tetrazaindene sodium salt per mole silver was incorporated in the emulsion, and immediately thereafter 1.3 mg. potassium chloroaurate per mole of silver was added to the emulsion. The temperature of the emulsion was held at about 50 C. for about 10 minutes, and then allowed to cool. The emulsion was coated on a support and subjected to radiation from a commonly used red safelight. The emulsion was found to be essentially free from fog whereas a control emulsion, which was the same as the test emulsion except that the noble metal salt was added before the tetrazaindene salt, was badly fogged when tested in the same manner. The emulsion in accordance with the invention possessed good sensitivity to X-ray intensifying screen radiation. The addition of the salts in accordance with the invention does not modify the sensitivity of the emulsion to X-ray radiation.
In accordance with the invention, I may use any of the tetrazaindene salts which are antifoggants for silver halide emulsions and which impart red sensitivity to the emulsion, for example, those described by Carroll et al. U.S. Patent 2,716,062 or Tinker et al. U.S. Patent 2,835,- 581, in the form of their alkali metal or ammonium salts. Particularly suitable are the 4-oxo or 4-hydroxytetrazaindenes, e.g., salts of the 4-hydroxy-l,3,3a,7- tetrazaindenes. These tetrazaindenes may contain various substituents, such as hydroxy, alkyl, amino and carboxyl. The salts may be conveniently prepared, for example, by reacting hydroxyl or carboxyl containing tetrazaindenes with an alkali metal hydroxide. The tetrazaindene salt may be employed in amounts of from 0.25 to 10, and preferably 1.0 to 5.0 g. per mole of silver.
Preferably, the noble metal salts which are employed are water soluble, although insoluble noble metal salts may be used. Representative salts of the noble rnetals, such as ruthenium, rhodium, palladium, iridium and platinum, which may be used include ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite. Advantageously, a soluble gold salt is used, potassium chloroaurate being particularly suitable. Other representative useful gold salts include potassium aurithiocyanate, auric trichloride and 2-aurosulfobenzothiazole methochloride. The noble metal salts are preferably employed in amounts of 1.0 to 5.0 mg. per mole of silver, although the most useful range is 0.25 to 10 mg. per mole of silver.
The independent addition to an emulsion of a noble metal salt subsequent to after-ripening of the emulsion lowers the sensitivity to red radiation. If desired, a noble metal salt may also be added to the emulsion before the after-ripening to increase sensitivity; advantageously, a gold salt is employed. In this instance, other sensitizers may be used with the gold (or noble metal) salts if desired, such as sulfur sensitizers, for example, those described in Sheppard et al. U.S. Patents 1,574,944, 1,623,- 499 and 2,410,689.
As indicated above, the tetrazaindene salt is added to the emulsion first and then the noble metal salt is incorporated therein. The salts must be added to the emulsion at the earliest, at the end of the after-ripening or second digestion, or anytime thereafter. It is necessary to add the tetrazaindene salt subsequent to the after-ripening step in the emulsion preparation since such salts would inhibit the effect of chemical sensitizers it added at an earlier stage of the emulsion preparation.
The addition of the tetrazaindene and noble metal salts is followed by a short period of digestion of the emulsion, such as from about 1-10 minutes at about 50 C. Advantageously, the salts are added during cooling of the emulsion after the second digestion, and while the emulsion is at about 50 C.
The invention is applicable to emulsions containing tetrazaindene salt antifoggants, which emulsions are not spectrally sensitized, or are spectrally sensitized only to the green region of the spectrum. The invention is particularly useful with medical X-ray emulsions which are not spectrally sensitized, but which may, of course, be chemically sensitized.
Emulsions in accordance with the invention have good fog stability and are substantially insensitive to the conventional red safelights employed in the photographic industry. Such safelights may be prepared, for example, by covering a 15 or 25 watt tungsten bulb with a filter which transmits light substantially only in the red region of the spectrum.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.
I claim:
1. In a method of preparing photographic silver halide X-ray emulsions containing tetrazaindene salt antifoggant, which method comprises the steps of emulsification, removal of soluble salts and after-ripening, and separate additions' following the after-ripening step of both a tetrazaindene salt and from 0.25 to mg. per mole silver of a noble metal salt to said emulsion, the improvement wherein said additions following the after-ripening step are performed in the order of first adding said tetrazaindene salt and thereafter adding said noble metal salt whereby red-safelight sensitivity of the emulsion is maintained below the red-safelight sensitivity that would obtain by opposite order of said additions.
2. An improved method defined by claim 1 further comprising a step of digesting the emulsion for a short time following the defined additions of tetrazaindene and noble metal salts.
3. A method defined by claim 1 wherein the defined tetrazaindene salt is a Water-soluble 4-oxotetrazaindene salt and the defined noble metal salt is a water-soluble gold salt.
4. A method defined by claim 1 wherein the defined tetrazaindene salt is an alkali metal salt of a 4-hydroXy-1,3, 3a,7-tetrazaindene and the defined noble metal salt is a water-soluble gold salt.
5. In a method of preparing photographic silver halide X-ray emulsions containing tetrazaindene salt antifoggant, which method comprises the steps of emulsification, removal of soluble salts and after-ripening, the improvement which comprises first adding to the emulsion, while it is cooling subsequent to the after-ripening step, at about C., about 1 g. per mole silver of 4-hydroxy-6-methyl- 1,3,3a,7-tetrazaindene sodium salt, and following said first addition adding to the emulsion about 1.3 mg. per mole silver of potassium chloroaurate.
6. A photographic emulsion prepared in accordance with the method of claim 1.
References Cited UNITED STATES PATENTS 2,597,856 5/ 1967 Damschroder 96-108 X 2,716,062 8/1955 Carroll 96-109 X NORMAN G. TORCHIN, Primary Examiner. R. E. FICHTER, Assistant Examiner.
US382407A 1963-12-05 1964-07-13 Method for stabilizing x-ray emulsions to red safelights Expired - Lifetime US3411914A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR956168A FR1385606A (en) 1963-12-05 1963-12-05 New photographic emulsions with very low sensitivity to light from safety lamps

Publications (1)

Publication Number Publication Date
US3411914A true US3411914A (en) 1968-11-19

Family

ID=8818187

Family Applications (1)

Application Number Title Priority Date Filing Date
US382407A Expired - Lifetime US3411914A (en) 1963-12-05 1964-07-13 Method for stabilizing x-ray emulsions to red safelights

Country Status (5)

Country Link
US (1) US3411914A (en)
BE (1) BE656175A (en)
DE (1) DE1242094B (en)
FR (1) FR1385606A (en)
GB (1) GB1085638A (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0562476A1 (en) 1992-03-19 1993-09-29 Fuji Photo Film Co., Ltd. A silver halide photographic emulsion and a photographic light-sensitive material
EP0563985A1 (en) 1992-04-03 1993-10-06 Fuji Photo Film Co., Ltd. Silver halide color photographic material
US5389511A (en) * 1991-11-06 1995-02-14 Konica Corporation Silver halide photographic emulsion and light-sensitive silver halide photographic material making use of the same
EP0691569A1 (en) 1994-07-04 1996-01-10 Kodak-Pathe Photographic emulsion with improved sensitivity
EP0772079A2 (en) 1995-10-31 1997-05-07 Eastman Kodak Company Light-sensitive silber halide emulsions and processes for their preparation
EP0777153A1 (en) 1995-11-30 1997-06-04 Fuji Photo Film Co., Ltd. Silver halide color photographic light-sensitive material
EP1624337A2 (en) 2004-08-02 2006-02-08 Fuji Photo Film Co., Ltd. Silver halide holographic sensitive material and system for taking holographic images by using the same
EP1691237A2 (en) 2005-02-15 2006-08-16 Fuji Photo Film Co., Ltd. Holographic recording material and holographic recording method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58126526A (en) * 1981-12-19 1983-07-28 Konishiroku Photo Ind Co Ltd Manufacture of silver halide emulsion, and photosensitive silver halide material
EP0107488A3 (en) * 1982-10-22 1984-06-27 Konica Corporation Silver halide emulsions

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597856A (en) * 1949-09-24 1952-05-27 Eastman Kodak Co Stabilization of photographic emulsions sensitized with gold compounds
US2716062A (en) * 1953-07-01 1955-08-23 Eastman Kodak Co 4-hydroxy-6-alkyl-1, 3, 3a, 7-tetrazaindene stabilizers for emulsions sensitized with alkylene oxide polymers

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1151437B (en) * 1961-07-17 1963-07-11 Wolfen Filmfab Veb Process for increasing the sensitivity of photographic silver halide emulsions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597856A (en) * 1949-09-24 1952-05-27 Eastman Kodak Co Stabilization of photographic emulsions sensitized with gold compounds
US2716062A (en) * 1953-07-01 1955-08-23 Eastman Kodak Co 4-hydroxy-6-alkyl-1, 3, 3a, 7-tetrazaindene stabilizers for emulsions sensitized with alkylene oxide polymers

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5389511A (en) * 1991-11-06 1995-02-14 Konica Corporation Silver halide photographic emulsion and light-sensitive silver halide photographic material making use of the same
EP0562476A1 (en) 1992-03-19 1993-09-29 Fuji Photo Film Co., Ltd. A silver halide photographic emulsion and a photographic light-sensitive material
EP0563985A1 (en) 1992-04-03 1993-10-06 Fuji Photo Film Co., Ltd. Silver halide color photographic material
EP0691569A1 (en) 1994-07-04 1996-01-10 Kodak-Pathe Photographic emulsion with improved sensitivity
EP0772079A2 (en) 1995-10-31 1997-05-07 Eastman Kodak Company Light-sensitive silber halide emulsions and processes for their preparation
EP0777153A1 (en) 1995-11-30 1997-06-04 Fuji Photo Film Co., Ltd. Silver halide color photographic light-sensitive material
EP1624337A2 (en) 2004-08-02 2006-02-08 Fuji Photo Film Co., Ltd. Silver halide holographic sensitive material and system for taking holographic images by using the same
EP1691237A2 (en) 2005-02-15 2006-08-16 Fuji Photo Film Co., Ltd. Holographic recording material and holographic recording method

Also Published As

Publication number Publication date
FR1385606A (en) 1965-01-15
BE656175A (en) 1965-03-16
DE1242094B (en) 1967-06-08
GB1085638A (en) 1967-10-04

Similar Documents

Publication Publication Date Title
US2839405A (en) Inorganic salt antifoggants for photographic emulsions
USRE29974E (en) Silver salt direct positive emulsion
US2716062A (en) 4-hydroxy-6-alkyl-1, 3, 3a, 7-tetrazaindene stabilizers for emulsions sensitized with alkylene oxide polymers
US3411914A (en) Method for stabilizing x-ray emulsions to red safelights
US3531289A (en) Silver halide photographic emulsions improved by new precipitation methods
US2598079A (en) High-speed photographic silver halide emulsions supersensitized with palladium salts
US3038805A (en) Non-polymeric open-chain sensitizers
US3901711A (en) Silver halide photographic emulsion containing a gold salt and a polyalkylene oxide
US2983609A (en) Chemical sensitization of photographic emulsions
US3519426A (en) Preparation of silver halide emulsions having high covering power
US3477852A (en) Direct-positive silver halide emulsion resistant to kink-marking desensitization
US2955036A (en) Fog reduction in photographic silver halide emulsions
US3266897A (en) Antifoggant agents for photography
US3703584A (en) Process of sensitizing converted-type silver halide emulsions with noble-metal salts
US2772164A (en) Photographic silver halide emulsions containing 1-thia-3, 5, 7-triazaindenes
US2743180A (en) Pentazaindene stabilizers for photo-graphic emulsions sensitized with alkylene oxide polymers
US3312553A (en) Photographic materials
US2835581A (en) Tetrazaindenes and photographic emulsions containing them
US2756147A (en) Tetrazaindene stabilizer for photographic emulsions sensitized with alkylene oxide polymers
US4067740A (en) Trithiocarbonates as sensitizers for silver halide emulsions
US3408197A (en) Synergistic sensitization of silver halide emulsions with labile selenium formed in situ
US2952539A (en) Photographic emulsions and developers stabilized with purine compounds
US3202512A (en) Photographic silver halide emulsions stabilized with tetrazaindene compounds
US2887378A (en) Photographic silver halide emulsions containing thiol compounds
US2852375A (en) New tetrazaindene compounds and photographic emulsions containing them