Silver halide emulsion

CH rCHCH NHCSNH. Colourless crystalline solid with a faint garlic-like odour m.p. 74 C. Manufactured by treating propenyl isothiocyanate with a solution of ammonia in alcohol. It has been given by injection in the treatment of conditions associated with the formation of excessive fibrous tissue. Toxic side reactions may occur. Propenyl thiourea is a chemical sensitizer for photographic silver halide emulsions. 

In certain carbocyanines. used as photographic sensitizers in silver halide emulsions, selenazoline rings linked bv trimethine bridges are found (56, 72). 

E. J. Birr, Stabili tion of Photographic Silver Halide Emulsions Eocal Press, Inc., New York, 1974. 

If enough ammonia is added to a precipitate of silver halide, all the precipitate dissolves. A similar procedure is used to remove the silver halide emulsion from an... 

The dyes that perform this function are called spectral sensitisers because they are used to sensitise the photographic emulsion to light across the whole visible spectrum and beyond. Since silver halides are naturally blue sensitive, the green and red spectral sensitiser dyes must also be able to reduce the natural sensitivity of the silver halide emulsion to blue light. The most important class of compounds used in this... 

Photographic emulsions. These are very commonly used, the silver halide emulsions are coated on glass or transparent polymer film. The emulsions, which involve the use of ultrafine grain size silver halide, are available for response to a range of laser wavelengths. This is the mainstay method in graphics art outlets. 

The conversion efficiencies, tIq should be at least 15%. The preferred emission spectra are in me near ultraviolet to match the spectral sensitivity of silver halide emulsions, rif i and to reduce cross over, nf2 ... 

The major uses of heterocyclic compounds in black and white processes are in controlling the hardness of gelatin, in optimizing the performance of the silver halide emulsions, in absorbing unwanted radiation and as components in the processing solutions. 

Silver halides are naturally sensitive to ultraviolet and blue light only. That it is possible to photograph objects of all colours is the consequence of the discovery, made in 1873, of the means of extending the sensitivity of silver halides into regions of the visible light spectrum beyond the blue. This was achieved by the addition of a dye in a small amount to a silver halide emulsion which was thereby rendered sensitive to the light absorbed by the dye (1873CB1302). 

Silver halide emulsion layers containing the substituted 5(7)-hydroxytri-azolo[4,3-a]pyrimidine derivatives are used as photographic materials [91JAP(K)03/13934]. 

Hydroxyhydroquinone and pyrogallol can be used for lining reactors for vinyl chloride suspension polymerization to prevent formation of polymer deposits on the reactor walls (98). Hydroxyhydroquinone and certain of its derivatives are useful as auxiliary developers for silver halide emulsions in photographic material their action is based on the dye diffusion-transfer process. The transferred picture has good contrast and stain-free highlights (99). 5-Acylhydroxyhydroquinones are useful as stabilizer components for poly(alkylene oxide)s (100). 

Spectral Sensitization. Photographic silver halide emulsions are active with light only up to about 500 nm. However, their sensitivity can be extended within the whole visible and near-ir spectral region up to about 1200—1300 nm. This is reached by the addition of deeply colored dyes that transfer excited electrons or excitation eneigy to the silver halide. 

Oxadiazole derivatives have been tested in the textile industry as antistatic agents for textile finishes,232,233 thermally stable polymers,82, 234,235 fluorescent whiteners,236 oil and water repellents on cotton and wool,237 and blue dyes for polyesters and polyamides.238 Oxadiazole merocyanine dyes have been patented as photosensitizers for silver halide emulsions.239... 

Color sensitizers are dyes added to silver halide emulsions to broaden their response to various wavelengths. Unsensitized emulsions are most responsive in the blue region of the spectrum and thus do not correctly represent the light spectrum striking them. Widely used sensitizers include the cyanine dyes, the merocyanines. the benzooxazoles, and the hcn/n11iki/oIl1 s Cryplocyaniiie sensitizes the extreme red and infrared. 

Coordination compounds and coordination chemistry are involved in a number of these steps. Chemical sensitizing agents, antifoggants and stabilizers are discussed separately. This discussion concerns silver halide emulsion precipitation and physical ripening methods. 

In contrast to using metal complex developers in solution, metal salt developer precursors such as CuNCS, C0CO3, CoC204 or MnC204 can be incorporated directly into silver halide emulsion layers. After exposure, the emulsion is developed by immersion in an ethylenediamine or other amine solution, generating a complex ion developer in situ. 2... 

Polycyclic sulfur compounds were used for silver halide emulsion and silver halide photographic material C1994JPP06118537, 1995JPP06102610, 1997JPP09061956, 1999JPP11119368, 2000JPP2000047344,... 

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