OPTICAL-ABSORPTION SPECTRA OF LIQUID AS2S3 AND AS2SE3 OVER A WIDE TEMPERATURE-RANGE

We have measured the optical absorption coefficient of liquid As2S3 and As2Se3 up to 900-degrees-C in a wide absorption range up to about 3 x 10(5) cm-1. We have developed an optical cell of our own design with a sample thickness of about 2000 angstrom. The optical gap obtained from the spectra decreases rapidly with increasing temperature, eventually becoming zero at about 950-degrees-C for liquid As2Se3, where the semiconductor-to-metal transition starts to occur.