OPTICALLY INDUCED CRYSTAL-TO-AMORPHOUS-STATE TRANSITION IN AS2S3

The optically induced transition of crystalline As2S3 (orpiment) to th e amorphous state was studied using Raman spectroscopy. The illuminati on of As2S3 crystals by Kr laser light (530.9 and 568.2 nm wavelength) rapidly reduces the intensities of the narrow Raman lines of c-As2S3, while increasing the intensities of broad Raman bands (340 cm(-1), 23 1 cm(-1)) typical of the amorphous state. The origin of the effect is non-thermal; the light probably decreases the kinetic barrier for the disordered crystal-to-amorphous-state transition.