Photo-induced ring-to-chain conversion in as-evaporated films of amorphous selenium.

Results of an in-situ extended X-ray absorption fine-structure study of photostructural changes in films of amorphous selenium are reported. It is shown that at first the average coordination number decreases by about 10%. As time elapses, the initial coordination number is restored. This change is attributed to breaking of ring-like structural fragments with subsequent formation of longer chains. This model is supported by a Raman scattering experiment demonstrating the disappearance upon photoexcitation of a peak at about 112 cm -1 characteristic of rings. [ABSTRACT FROM AUTHOR]