Aurous thiocyanate complex

Most Intensification treatments accelerate development as well as increase the effective speed of the photographic material. The gold Intensification is especially notable in this respect, and is of interest in relation to the mechanism of development. A simple motion picture positive film responds well to the gold treatment, which consists simply in bathing the exposed film for a few minutes in a solution containing the aurous thiocyanate complex in the presence of excess thiocyanate and bromide ions. Figure 7 shows the developed densities for several... 

Mechanism of Sensitization. Photoconductivity (170) and Dember effect (171) studies on emulsions sensitized by aurous thiocyanate complex used without S-sensitizers are consistent with hole trapping. Faelens (170) observed that the aurous thiocyanate sensitization increased the photoconductivity, but thiocyanate ion alone caused a similar increase. Hence, the product formed by the action of the aurous complex may not be... 

Duglav and associates (173), in a study of the photoelectro-motive force in emulsion layers, observed an increase in the EMF with increasing time of sensitization in the presence of aurous thiocyanate complex. They attribute this increase to photohole capture and to decreased activity of photoelectron capture. Sensitization by stannous chloride, which forms reduction centers, produced a similar increase in photo EMF amplitude with increasing time of sensitization. (S+Au)-sensitization, however, does not provide for complete removal of holes in many emulsions. This is shown by the further increases in sensitivity obtained by hydrogen hypersensitization of both experimental and commercial emulsions (108). 

Koslowsky in 1936 observed that certain gold salts, such as aurous thiocyanate and aurous thiosulfate complexes, are sensitizers, but this discovery remained a trade secret for several years (157-159). Gold salts used alone are relatively poor sensitizers, but in combination with sulfur sensitizers they can increase the sensitivity beyond that obtainable by S-sensitiza-tion alone (160). 

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See also in sourсe #XX -- [ ]

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