Confined Raman Scattering - Easy Access to the Surface Phonons of Specific Crystalline Solids

Abstract

An easily feasible method to measure surface phonons of specific crystalline solids is described. Special experimental conditions allow confining Raman scattering to the surface region of crystals, while the contribution of bulk scattering to the spectra is largely excluded. Such conditions exist for example in the case of hexaborides, using FT Raman spectroscopy with a commercial spectrometer with ND:YAG laser excitation. We show results obtained on LaB 6, SmB 6 and boron carbide. The surface phonon spectra of LaB 6 are analyzed by comparing them with bulk spectra and discussed in comparison with results of other experimental methods and theoretical calculations.