Resonant Raman Scattering in ZnS

Three Raman lines were observed in addition to excitonic emission lines in cubic ZnS using a He-Cd laser 325 nm line. The lines were assigned to the Raman lines of the laser line scattered by one or two phonons. The energies of the LO phonon and the TO phonon were estimated to be 44 meV and 35 meV from the energy of the Raman lines. These values agreed well with those measured by right-angle Raman scattering with an Ar laser 514.5 nm line. With the rise in temperature from 4.2 K, the intensity of the Raman lines declined until 80 K and was then enhanced to about 130 K. The temperatures where the intensity was enhanced corresponded to those where the energy of the free exciton level approached the energies of the Raman lines. The temperature dependence of the Raman intensity was interpreted in terms of resonance between the incident or scattered light with the temperature-dependent free exciton level.