ACTA PHYSICA POLONICA A, vol.102, no.6, pp.801-810, 2002 (SCI-Expanded)
Systematic measurements by Raman scattering. of the frequency and line width of the zone-center optical modes in GaS0.25Se0.75 layered crystal over the temperature, range of 10-300 K are carried out. The analysis of-temperature dependence of intralayer modes shows that frequency shift and line broadening are successfully modeled by including the contributions from thermal expansion and lattice anharmonicity. The purely anharmonic contribution (phonon-phonon coupling) is found to be due to three-phonon processes.