Date: 25 Sep 2014
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Dye-Sensitization

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Definition

Photosensitization can be defined as a process in which light absorption by a photosensitizer molecule leads to a photophysical or photochemical change in a second molecule or system.

History

The scientific term sensitization referred originally to the process by which a photographic film or plate was made more sensitive to particular wavelengths of light. The history of dye-sensitization began in 1873 with the discovery by Hermann Wilhelm Vogel (1834–1898) that the sensitivity of silver halide photographic plates to green and red light was greatly enhanced by the presence of dyes in the photographic emulsion. Using a “cocktail” of different colored dyes, Vogel was able to achieve tone balance in black and white photographs [1]. It is now generally accepted that the photoexcited state of the dye injects electrons into the silver halide, leading to the formation of silver atoms. The oxidized dye can be regenerated by electron transfer from a “supersensitizer” su ...