Photostructural changes in amorphous chalcogenides

Chalcogenide glasses respond to irradiation with optical or ultraviolet photons in a unique manner. They exhibit photostructural effects. Photostructural effects, in general, fall into two different categories. The first category is based on changes in scalar properties. 

Photo-darkening and light induced electron spin resonance (ESR) are typical examples of reversible photo-induced effects. Photo darkening occurs when the material is irradiated with band gap photons 

Xerography The high electrical resistivities and optical absorptivities of chalcogenides have lead to many important applications. One of the most remarkable applications is in xerography (dry writing). The principle involved is simply as follows (i) Se film coated on an aluminium substrate is exposed to corona discharge in order to charge the selenium 

The activation barriers for transport of bipolarons (Cf centers) has to be the difference in the pairing energies in orbitals of Pb and in sp orbitals of Se which is designated as At//,/ . Using plausible values of the various parameters (Table 8.3), the expected conductivities and thermo- 

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Shimakawa K, Yoshida N., Ganjoo A., and Kuzukawa Y, A model for the photostructural changes in amorphous chalcogenides, Philos. Mag. Lett. 77,153-158 (1998). 

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