Photographic applications silver halide

An industrial application is provided by a reaction important in photographic processing. On exposure to light, the silver halide in photo-... 

Such dyes found early application as sensitizers in photography and many thousands of related structures have been made. Suitable dyes when added to the photographic emulsion extend the sensitivity of the silver halide from the blue and UV region towards the green, red and near IR. The sensitivity of the dyes can be balanced throughout the visible spectrum to give panchromatic emulsions. 

Another very useful technique that alleviates some of the aforementioned difficulties is the controlled double-jet precipitation (CDJP) process, which can be extended to a triple jet design. The technique was originally developed to produce uniform large particles (23-25), particularly of silver halides for photographic applications. Recently, it was demonstrated that the procedure may be used for the synthesis of a variety of uniform dispersions, including those of metal oxides of different modal sizes, ranging from several nanometers to several micrometers (26-29). 

The reactions which will be discussed here are basic in the application of dyes as sensitizer for photographic materials like silver halides, zinc oxide and others. Model experiments can be performed at electrodes of such materials which help to understand the mechanism of spectral sensitization in photography. 

Materials for use in black and white processes are obtained in the following way. A photographic emulsion is prepared by precipitating either a silver halide or a mixture of silver halides in a polymeric medium which is usually gelatin. This emulsion is then coated as a very thin layer on to a support such as film or paper. The coating is dried, and the support is cut into sizes appropriate to specific applications and stored in light-proof containers. 

The coverage has been limited to the applications of coordination compounds or of the coordination chemistry of relatively soluble ligands and metal species. Numerous chemical agents in photographic systems function by means of adsorption on silver halide grains and silver metal surfaces. Such chemical interactions lie outside the confines of coordination chemistry defined for this work and have not been discussed. 

Like the more widely used 1,2,3-triazoles, many 1,2,4-triazole derivatives find application in photography thanks to the adsorption of thiones on silver halides, reactivity with silver compounds or the formation of disulfides as potential free radicals. Also 5-propargylthiol (344) stabilizes photographic emulsions (74GEP2304321). 

Another important application to photography of our understanding of the cluster formation mechanism in radiation chemistry is the enhancement of the sensitivity of photographic emulsions (Fig. 11) [16]. The primary effect ofthe photon absorption by the silver halide crystals of the emulsion during the exposure is indeed to produce one... 

The photographic process, another photoimaging technique (see also Special Topic 6.27), is still the most widespread application of photochemistry.1547 IR, visible, UV and X-ray irradiation of photosensitive silver halide (Ag + X ) crystals in a gelatine emulsion, coated on a film base, glass or paper substrate, causes reduction of interstitial... 

A correlation of the photosensitivities of several organic photochemical systems with this theoretical value is given in Table 1, where the sensitivity of some silver halide materials were Included for comparison. It Is trivial to state that the success of classical photographic systems, considered from the point of view of their photosensitivity, lies in the possibility of chemical amplification of the latent image. It seems therefore evident that the only chance for organic photochemical systems to realize a significant penetration Into the broad application field of silver systems with sensitivities of 10 ergs/cm and less Is to find some way to amplify the primary photochemical effect - that is, to find photochemical reactions with an overall... 

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