Lattice bands in germanium

e infra-red lattice bands of germanium have been remeasured and interpreted as multiple phonon bands involving four characteristic phonon energies. These energies are found to agree closely with the energies of the four maxima in the density of states curve calculated from the Cochran `shell' model. This observation supports the view that the form of the lattice bands is determined primarily by the summation over states rather than by specific selection rules.