Two-phonon infra-red lattice absorption in diamond

Abstract

The specimen independent infra-red absorption spectrum of diamond in the 2 μ to 6 μ region has been examined using a grating spectrometer. The results have been analysed in terms of multi-phonon processes. In particular the two-phonon absorption has been examined in detail in an attempt to deduce phonon energies for the various branches of the frequency spectrum at symmetry points in the reduced zone. Sets of lattice wave dispersion curves have been constructed from these results and are very unlike those for silicon and germanium.