Anharmonic effects in phonon spectra of GaSe.

The different manifestations of the crystalline potential anharmonicity in GaSe were studied. The temperature dependence of one and multiphonon mode energies was obtained from infrared absorption and Raman scattering experiments. The temperature and frequency dependence of multiphonon absorption coefficient were discussed.

Refractive index of GaSe between 0.45 microm and 330 microm.

Using the natural properties of the lamellar compounds, the ordinary refractive index of GaSe has been induced from interferential patterns of transmission and reflection spectra in the low absorption range and from reflectivity spectra in the polar modes range. An analytic development of the refractive index vs energy can reproduce the measured values of this index and provides the energy gap in the visible range, and values for omega(LO) and omega(TO) in the ir range infinity have been used as a parameter to get this fitting.