US2945763A - Green sensitization of photographic silver halide emulsions - Google Patents
Green sensitization of photographic silver halide emulsions Download PDFInfo
- Publication number
- US2945763A US2945763A US743069A US74306958A US2945763A US 2945763 A US2945763 A US 2945763A US 743069 A US743069 A US 743069A US 74306958 A US74306958 A US 74306958A US 2945763 A US2945763 A US 2945763A
- Authority
- US
- United States
- Prior art keywords
- group
- dye
- dyes
- formula
- emulsions
- 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
Links
Images
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
- G03C1/08—Sensitivity-increasing substances
- G03C1/10—Organic substances
- G03C1/12—Methine and polymethine dyes
- G03C1/14—Methine and polymethine dyes with an odd number of CH groups
- G03C1/18—Methine and polymethine dyes with an odd number of CH groups with three CH groups
-
- 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
- G03C1/28—Sensitivity-increasing substances together with supersensitising substances
Definitions
- This invention relates to photography, and more particularly, to a method for altering the sensitivityV of greensensitized photographic silver halide emulsions. ⁇
- benzimidazolocarbocyanine dyes are useful in sensitizing photographic silver halide Y emulsions to the green region of the spectrum, i.e., ⁇ that portion of the-spectrum lying between aboutV 50Oand, 60'() ma. These dyes have been of particular interestras greensensitizers, andl in particular, in the emulsions intended for use in color photography,V since they aregenera-lly characterized by very sharp absorption. Dyes of this type have been previously described inthe technical and patent literature. See, for example, Ogata Proceedings of the Imperial Academy (Tokyo), v ol. 9 (1933), page- 602,. Among the most useful of the benzimidazolocarbocyanine dyes are those containing one or more chlorine atoms substituted on the benzene ring of the benzimidazole nucleus. Y
- an ⁇ object of my invention to. provide an improved means of sensitizing photographic silver halide emulsions to the green region of the spectrum. Another object is to produce vein silver halide', emulsions having improved green, sensitivity.k Still, an: other object is to provide photographic silver-halide emulsions which have been supersensitized bya combination of! the above-mentioned sensitizing dyes' with4 certain heterocyclic compoundsv as hereinafter defined.
- sensitizing dyes include those representedlby the followingV general formula:
- R andv R1k each represents and alkyl group; suchV asmethyl, ethyl, Ilit-hydroxyethyl, n-propyl', nbutyl', ,tt-r'zar box-yethyl, y-carboxypropyl, (or 4,).l-carboxylhutyl", )9s-sulfoethyl, y-sullfoinopyL ⁇ ⁇ i-sulfelmtyl.,v fsulfebutyl, etc.
- Patent O ⁇ ice 2 Y (e, .g., an alkyl group ⁇ ycontaining from 1 to 4; carbon atoms), R2 and R3 each represents an alkyl group, such as methyl, ethyl, n-propyl, n-butyl, etcte-a, ⁇ an alkyl Kunststoff containing from 1 to 4 carbon atoms.) Aor, an aryl group, such as phenyl, o, mor p-tolyl, etc.
- d and 1 1 each.rep-4 resents a positive integer of from l to- 3 and X, represents an acid radical, such as chloride, bromide, iodide, benzenesulfonate, p-toluenesulfonate, methylsulfate ethylsulfate,
- R or R1 of Formula I represents acid-substituted alkyl groups, such as a sulfoalkyl group
- the dyes are generally regarded as anhydro dyes, and, a particularly useful group of such dyes can be represented by the following general formula:
- R has the values given above, and ⁇ D represents an alkylenel group, such as'ethyl'ene, trimethylene, tetra- Y methylene, ymethyltrimethylene, etc.
- Another.' group of dyes embraced by Formula I which are particularly useful in my invention can be representedby the following general formula:
- R5r represents an alkyl group, such as methyl, ethyl, etc. (e.g., an alkyl group containing from l to 2 carbon atoms), or an aryl group, such as phenyl, o, mor p-tolyl (e.gl, a' mononuclear aromatic, group, of the benzene series), Q; represents an oxygen atom or an arylimino group, such as phenylimino, tolylimino, chlorophenylimino, etc.
- Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazoline series or the naphthoselenazoline series.
- the carbocyclicY rings ofthe nuclei defined by Z above can contain inert substituents, such as alkyl groups (e.g., methyl, ethyl, etc.), alkoXy groups (e.g., methoXyl, ethoxyl, etc.), etc.
- the compounds of Formula II, wherein Q represents Il C-:CH-C-CHS an oxygen atom can be prepared according to the method described in Brooker et al. U.S. Patent 2,112,139, issued March 22, 1938.
- the compounds of Formula II, wherein Q represents an arylimino group can be prepared as described in Brooker et al. U.S. Patent 2,298,732, issued October 13, 1942.
- the degree of hypsochromic shift in the absorption ofthe benzimidazolocarbocyanine dyes can be controlled to some extent by the amount of the compound of Formula II which is added.
- addition of increased quantities of the compoundrof Formula II will produce an increased shift in absorption up to a point which varies from dye to dye and addition vof further quantities of the compounds of Formula II beyond that point does not produce a corresponding shift in the absorption characteristics.
- the optimum amount of the compound of Formula II employed in my invention can vary, depending upon-the effect desired.
- the most advantageous amounts of the sensitizing dye and the compound of Formula II can be determined by running a series of test emulsions wherein various quantities of either ingredient are employed.
- the amount of sensitizing dye used can vary rather widely and I have found that from about 5 to about 200 mg. per mole of silver halide are quite adequate.
- the amount of compound of Formula II can likewise be varied, as described above, and I have found that from about 10V to about 200 mg. per mole of silver halide of the compounds of Formula II are quite adequate.
- VThe ratio of the amount of sensitizing dye to the compound of Formula II can likewise be varied, and I have found that, in general, this ratio can vary from about 1:5 to about 5:1 (by. weight).
- the emulsions can then be digested for a short period of time prior to coating on a suitable support, such asv glass, cellulose derivative iilm, metal, paper, polyvinyl .acetal film, etc. After coating to a suitable thickness, the film can then be allowed to dry.
- a suitable support such asv glass, cellulose derivative iilm, metal, paper, polyvinyl .acetal film, etc.
- My invention is primarily directed to the ordinarily employed gelatino-silvenhalide developing-out emulsions, e.g., gelatino-silver-chloride, -chlorobromide, -chloroiodide, -chlorobromiodide, bromide and -bromiodide developing-out emulsions. While the results inthe following table were obtained using gelatino-silver-bromiodide emulsions, 'excellent vresults have 4also been obtained using gelatino-silver-chlorobromide emulsions.
- Emulsions which form the latentrimage mostly inside the silver halide grains such as theI emulsions set forth in E. B.- Knott et al. U.S. Patent 2,456,956, dated December 21, V194,8, lcan also be employed in practicing my 'invention.
- Photographic silver halide emulsions such as those listed above, containing the sensitizing combinations of my invention can also contain such addenda eis-chemical sensitizers, eg., sulfur sensitizers (eg, allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, -etc.), various gold compounds (e.g., potassium chloroaurate, auric trichloride, etc.) (see U.S. Patents W. D. Baldsiefen 2,540,085, granted February 6, 1951; R. E. Damschroder 2,597,856, granted May 27, 1952 and H. C. Yutzy et al.
- addenda eis-chemical sensitizers eg., sulfur sensitizers (eg, allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, -etc.), various gold compounds (e.g., potassium chloroaurate, au
- the Dye (a) of Table A produced a 275% increase in speed
- emulsion used was a conventional gelatino-silver-bromioalthough there was a shift in absorption of only from dide emulsion and the coatings were prepared as de- 576 to 572 mp.. i scribed for Table A.
- Exposure and development were As indicated above, many of the benzimidazolocarboidentical to that of Table A, the time of development cyanine dyes of my invention can be prepared according being about 4 minutes for each of the exposed coatings. to methods previously described in the prior art.
- curve A represents the reectance (percent) for a processed ordinary gelatino-silver-bromiodide emulsion containing anhydro-5,5,6,6 tetrachlorol,ldiethyl 3,3'di(3su1fobutyl)benzimidazolocarbocyanine hydroxide
- curve B represents the reectancef (percent) of the sensitized emulsion illustrated by curve A, butA to which 3-ethyl-2-(2-phenylimino-propylidene)--naphthoi thiazoline had been added.
- the sensitometric properties of these coatings are illustrated in Examples 6 and 7 above.
- curve C represents the reilectance (percent) of a processed ordinary gelatino-silver-bromiodide emulsion containing 5,5',6,6tetrach1oro1,l,3,3'tetraethyl benzimidazolocarbocyanine iodide
- curve D represents the reectance (percent) of the emulsion represented by curve C, to which 1-methyl-2benzoylmethylene l-naphthothiazoline had been added.
- the sensitometric .properties of these coatings yare shown in Examples 4 and 5 above.
- my invention contemplates benzimidazolocarbocyanine dyes containing two chlorine atoms on a single benzene ring of the benzimidazole nucleus, regardless of their position on the ring. It is to be understood that my invention also contemplates benzimidazolocarbocyanine dyes containing no substituents on the benzene ring of the benzimidazole nucleus.
- the reaction mixture was chilled and the solid filtered ol and then it was suspended in 60 ml. of water containing 2 g. of sodium iodide. After chilling for two hours, the crude dye was iiltered olf. The dye was suspended in 60% methyl alcohol and the suspension was heated to boiling and then cooled. After ltering, the dye was suspended in 60 ml. of methylV alcohol, cooled and tiltered. The dye was obtained as brownish crystals in a A6% yield, M.P. 205-206 C. with decomposition.
- the reaction mixture was chilled and the solid filtered off and then it was suspended in 60 ml. of water containing 2 g. of sodium iodide. After standing for two hours, the crude dye was tiltered off. The' dye was dissolved in 400 ml. of 70% -methyl alcohol and one ml. of triethylamine, the solution was filtered and the filtrate made acid with glacial acetic acid. The pure dye was obtained as brownish-orange crystals in a 5% yield, M.P. 256 257 C. with decomposition.
- the dye was suspended in 100ml, of ⁇ hot methyl alcohol, the suspension was ⁇ cooled and iiItered.
- the dye was obtained as reddish crystals VAin a 25% yield, M.P. 294-295 C. with dei composition. f
- Unsymmetrical benzimidazolocarbocyanine dyes useful'in my invention can be prepared as described in Gevaert Belgian Patent 532,735, vgranted November 13, 1954.
- R3 each represents a member selected from the group consisting of an'alkyl group and an aryl group, d'and n each represents a positive integer of from 1 to 3, and.
- X represents an acid radical, and (2) afcompound selected from those represented by the .following general formula.: l
- R4 represents an alkyl group
- R5 represents a member selected from the group consisting of an alkyl Vgroup and an aryl group
- Q represents a member vselected sions.V sIonre wherein Di represents an alkylene group
- R4 represents an alkyl group
- R5 represents a member selected from the group consisting of an alkyl group and anlaryl group
- Q represents a member selected from the group consisting of an oxygen atom and an arylimino group
- Z represents the non-metallic ato-ms climas 11 e necessary to complete a heterocyclic nucleus selected from the group consisting of those of the naphthothiazoline series and those of the naphthoselenazoline series.
- R and R1 each represents an alkyl group and X represents an acid radical, and (2) a compound selected from those represented by the following general formula: Y
- R4 represents an alkyl group
- R5 represents a member selected from the group consisting of an alkyl group and an aryl group
- Q represents a member selected from the group consisting of an oxygen atom and an arylimino group
- Z represents the nonmetallic atom's necessary to complete a heterocyclic nucleus selected from the group consisting of those of the naphthothiazoline series and those of the naphthoselenazoline series.
- R4' represents an alkyl group
- R5 represents a member selected from the group consisting of an alkyl group and an aryl group
- Q represents a member selected from the group consisting of an oxygen' atom and an arylimino group
- Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those ofthe naphthothiazoline series and those of the naphthoselenazoline series.
- D represents an alkylene group
- D represents an alkylene group
- R4 represents an alkyl group
- R5 represents a member selected from the group consisting of an alkyl group and an aryl group
- Q represents a member selected from the ⁇ group consisting of an oxygen atom and an arylimino group
- Z represents the non-metallic atoms necessary to complete a' heterocyclic nucleus selected vfrom the group consisting of those of the naphthothiazoline series and those of the naphthoselenazoline series.
- R and R1 each represents an alkyl group and X represents an acid radical
- R and R1 each represents an alkyl group and X represents an acid radical
- R and R1 each represents an alkyl group and X represents an acid radical
- R and R1 each represents an alkyl group and X represents an acid radical
- R and R1 each represents an alkyl group and X represents an acid radical
- R and R1 each represents an alkyl group and X represents an acid radical
- R and R1 each represents an alkyl group and X represents an acid radical
- R5 represents a member selected from the group consisting of an alkyl groupand an aryl group
- Q represents a member selected 'from thegroup consisting of an oxygen atom and an arylimino group
- Z represents the non-metallic atoms ,necessary/to Vcompletev a heterocyclic nucleus selected References Cited in the le of this patent UNITED STATES PATENTS f 2,1 12,139
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)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Developing Agents For Electrophotography (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BE579594D BE579594A (de) | 1958-06-19 | ||
US743069A US2945763A (en) | 1958-06-19 | 1958-06-19 | Green sensitization of photographic silver halide emulsions |
GB20535/59A GB914256A (en) | 1958-06-19 | 1959-06-16 | Sensitized photographic silver halide emulsions |
FR797986A FR1228644A (fr) | 1958-06-19 | 1959-06-19 | Nouvelle émulsion photographique chromatisée |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US743069A US2945763A (en) | 1958-06-19 | 1958-06-19 | Green sensitization of photographic silver halide emulsions |
Publications (1)
Publication Number | Publication Date |
---|---|
US2945763A true US2945763A (en) | 1960-07-19 |
Family
ID=24987402
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US743069A Expired - Lifetime US2945763A (en) | 1958-06-19 | 1958-06-19 | Green sensitization of photographic silver halide emulsions |
Country Status (4)
Country | Link |
---|---|
US (1) | US2945763A (de) |
BE (1) | BE579594A (de) |
FR (1) | FR1228644A (de) |
GB (1) | GB914256A (de) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3443955A (en) * | 1965-05-21 | 1969-05-13 | Ferrania Spa | Sensitized silver halide emulsions |
US3506443A (en) * | 1965-11-18 | 1970-04-14 | Eastman Kodak Co | Color photographic elements and process |
US3663211A (en) * | 1969-07-02 | 1972-05-16 | Gaf Corp | Silver halide emulsions containing unsymmetrical trimethine sensitizing dyes |
US3793020A (en) * | 1966-08-30 | 1974-02-19 | Fuji Photo Film Co Ltd | Photographic silver halide emulsions sensitized with benzimidazole cyanine dyes |
US3994733A (en) * | 1973-12-10 | 1976-11-30 | Fuji Photo Film Co., Ltd. | Silver halide photographic emulsion |
US4147553A (en) * | 1977-02-10 | 1979-04-03 | Fuji Photo Film Co., Ltd. | Supersensitized photographic emulsion |
US4581329A (en) * | 1983-03-11 | 1986-04-08 | Fuji Photo Film Co., Ltd. | Silver halide photographic light-sensitive material |
EP0200502A2 (de) | 1985-04-30 | 1986-11-05 | Konica Corporation | Lichtempfindliches farbphotographisches Silberhalogenidmaterial |
EP0202616A2 (de) | 1985-05-16 | 1986-11-26 | Konica Corporation | Verfahren zur Farbentwicklung eines photographischen lichtempfindlichen Silberhalogenidmaterials |
US5354646A (en) * | 1986-03-26 | 1994-10-11 | Konishiroku Photo Industry Co., Ltd. | Method capable of rapidly processing a silver halide color photographic light-sensitive material |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2112139A (en) * | 1935-07-05 | 1938-03-22 | Eastman Kodak Co | Acylmethylene derivatives of arylothiazolines and aryloselenazolines |
US2298732A (en) * | 1940-12-16 | 1942-10-13 | Eastman Kodak Co | Polymethine base |
US2694638A (en) * | 1953-08-13 | 1954-11-16 | Eastman Kodak Co | Supersensitization of carbocyanine dyes with hemicyanine bases |
US2739149A (en) * | 1953-02-27 | 1956-03-20 | Eastman Kodak Co | Symmetrical carbocyanine dyes |
US2778823A (en) * | 1954-08-23 | 1957-01-22 | Eastman Kodak Co | Benzimidazolocarbocyanine dyes |
-
0
- BE BE579594D patent/BE579594A/xx unknown
-
1958
- 1958-06-19 US US743069A patent/US2945763A/en not_active Expired - Lifetime
-
1959
- 1959-06-16 GB GB20535/59A patent/GB914256A/en not_active Expired
- 1959-06-19 FR FR797986A patent/FR1228644A/fr not_active Expired
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2112139A (en) * | 1935-07-05 | 1938-03-22 | Eastman Kodak Co | Acylmethylene derivatives of arylothiazolines and aryloselenazolines |
US2298732A (en) * | 1940-12-16 | 1942-10-13 | Eastman Kodak Co | Polymethine base |
US2739149A (en) * | 1953-02-27 | 1956-03-20 | Eastman Kodak Co | Symmetrical carbocyanine dyes |
US2694638A (en) * | 1953-08-13 | 1954-11-16 | Eastman Kodak Co | Supersensitization of carbocyanine dyes with hemicyanine bases |
US2778823A (en) * | 1954-08-23 | 1957-01-22 | Eastman Kodak Co | Benzimidazolocarbocyanine dyes |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3443955A (en) * | 1965-05-21 | 1969-05-13 | Ferrania Spa | Sensitized silver halide emulsions |
US3506443A (en) * | 1965-11-18 | 1970-04-14 | Eastman Kodak Co | Color photographic elements and process |
US3793020A (en) * | 1966-08-30 | 1974-02-19 | Fuji Photo Film Co Ltd | Photographic silver halide emulsions sensitized with benzimidazole cyanine dyes |
US3663211A (en) * | 1969-07-02 | 1972-05-16 | Gaf Corp | Silver halide emulsions containing unsymmetrical trimethine sensitizing dyes |
US3994733A (en) * | 1973-12-10 | 1976-11-30 | Fuji Photo Film Co., Ltd. | Silver halide photographic emulsion |
US4147553A (en) * | 1977-02-10 | 1979-04-03 | Fuji Photo Film Co., Ltd. | Supersensitized photographic emulsion |
US4581329A (en) * | 1983-03-11 | 1986-04-08 | Fuji Photo Film Co., Ltd. | Silver halide photographic light-sensitive material |
EP0200502A2 (de) | 1985-04-30 | 1986-11-05 | Konica Corporation | Lichtempfindliches farbphotographisches Silberhalogenidmaterial |
EP0202616A2 (de) | 1985-05-16 | 1986-11-26 | Konica Corporation | Verfahren zur Farbentwicklung eines photographischen lichtempfindlichen Silberhalogenidmaterials |
US5354646A (en) * | 1986-03-26 | 1994-10-11 | Konishiroku Photo Industry Co., Ltd. | Method capable of rapidly processing a silver halide color photographic light-sensitive material |
Also Published As
Publication number | Publication date |
---|---|
FR1228644A (fr) | 1960-08-31 |
GB914256A (en) | 1963-01-02 |
BE579594A (de) |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2688545A (en) | Supersensitization of photographic emulsions with benzimidazolocarbocyanine dyes | |
US3482978A (en) | Carbocyanine filter dyes and sensitizers for silver halide emulsions | |
US2977229A (en) | Supersensitized emulsions comprising simple cyanine dyes | |
US2955939A (en) | Holopolar cyanine dyes and photographic emulsions containing them | |
US2945763A (en) | Green sensitization of photographic silver halide emulsions | |
US3194805A (en) | Merocyanine and holopolar dyes containing arylene-chain substitution | |
US4576905A (en) | Photographically useful chalcogenazoles, chalcogenazolines, and chalcogenazolinium and chalcogenazolium salts | |
US2961318A (en) | Supersensitization of photographic emulsions containing planar cyanines | |
US2739149A (en) | Symmetrical carbocyanine dyes | |
US2701198A (en) | Supersensitized photographic emulsions containing simple cyanine dyes | |
US3632349A (en) | Silver halide supersensitized photographic emulsion | |
US4011086A (en) | Photographic emulsions and elements containing rigidized carbocyanine dyes | |
US3573920A (en) | Fine grain silver halide emulsions containing novel dye combinations | |
US2778823A (en) | Benzimidazolocarbocyanine dyes | |
US2848329A (en) | Supersensitization with bis-heterocyclic bases | |
US2464780A (en) | Dye-sensitized photographic silver halide emulsion | |
US2226158A (en) | Photographic emulsion | |
US3440053A (en) | Silver halide photographic emulsions containing allopolar cyanine dyes | |
US2635961A (en) | Supersensitization of photographic emulsions with complex merocyanine dyes | |
US2751298A (en) | Supersensitization of photographic emulsions with benzimidazolocyanine dyes | |
US2860984A (en) | Supersensitized photographic emulsions containing polymethine dyes and ketones | |
US3084045A (en) | Cyanine dyes derived from thienylben-zothiazoles and silver halide emulsions sensitized therewith | |
US2860982A (en) | Supersensitization of photographic silver halide emulsions | |
US3687674A (en) | Direct positive fogged silver halide emulsion sensitized with a cyclo-heptatriene cyanine dye | |
US2860981A (en) | Supersensitization of photographic silver halide emulsions |