Wave‐vector dependence of the electron energy losses of PbS, PbSe, and PbTe

The wave‐vector( q ‐)dependence of electron energy losses of cubic PbS, PbSe, and PbTe up to q ‐values near the first Brillouin zone boundary and up to energies of 40 eV is given. Anisotropic effects of the derived energy loss functions Im [−ε(ω, q ( ijk ))] −1 and dielectric functions ε 2 (ω, q ( ijk ))[( ijk ) = (100), (110), (111)] are observed and discussed in terms of present band structure calculations.