The local vibrational modes of the anion-site substitutional defect, CAs, were investigated by means of Fourier transform absorption spectroscopy at temperatures ranging from 10 to 450K. A new thermally activated line at 576.5/cm (300K) was attributed to the 5 ( = 1) to 5( = 2) transition. Analysis in terms of an anharmonic oscillator with Td symmetry gave a cubic potential parameter, |B|, of 6.4 x 1012J/m3. The fine structure of a second harmonic transition, 1 ( = 0) to 5( = 2), due to host isotope effects, was detected at low temperatures.

H.C.Alt: Materials Science Forum, 1995, 196-201, 1577-82