Silver halide photography light sensitivity

Within (say) the red-sensitive layer of a color-negative film, silver halide grains become sensitized by red light to form a latent image and are reduced to silver metal by a developer just as in black-and-white photography. In... 

An important practical application of dye-sensitization phenomenon is in the silver halide photography [11]. Various cyanine and related dyes are adsorbed onto silver halide microcrystals to extend the spectral response in the visible light region. The optimum efficiency of spectral sensitization of silver halide grains is known to be very high. 

All the silver halides are sensitive to light, decomposing eventually to silver. In sunlight, silver chloride turns first violet and finally black. The use of these compounds in photography depends on this (see below). (All silver salts are, in fact, photosensitive—the neck of a silver nitrate bottle is black owing to a deposit of silver.)... 

Photography based on silver halides as the light-sensitive material depends on physical and chemical properties that, although occurring individually in other compounds, form a combination in the silver salts that makes them unique in their... 

Silver forms monovalent ion in solution, which is colourless. Silver(II) compounds are unstable, but play an important role in silver-catalysed oxidation-reduction processes. Silver nitrate is readily soluble in water, silver acetate, nitrite and sulphate are less soluble, while all the other silver compounds are practically insoluble. Silver complexes are however soluble. Silver halides are sensitive to light these characteristics are widely utilized in photography. 

The analog photography community is well-versed with the fact that silver halides are tunable band gap semiconductors. Thus the photoactivity of AgCl can be tuned from the UV into the visible light region by a process known as self sensitization, which is due to the formation of Ag clusters during the photoreaction. The formation of these clusters introduces new levels within the forbidden gap that can now be populated by visible light (Fig. 7). 

Another important contribution of radiation chemistry in photography was the enhancement of the sensitivity of photographic emulsions. The primary effect of photon absorption by silver halides is the formation of an electron-hole pair. However, because of the very fast and efficient electron-hole recombination and oxidation by hole of the newly formed silver atoms, the conversion yield of light is very low. The analogy with HO oxidation processes occurring in irradiated solutions led to the use of the same scavenging method to inhibit the electron-hole pair recombination and the oxidation by the... 

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