Zur Ultrarotdispersion der Alkali-Halogenide

The infra-red spectra of LiF, NaCl and CsBr are interpreted according to the dispersion theory ofBorn andHuang1. This theory takes into account anharmonic terms in the lattice potential and leads to a frequency-dependent damping which describes the absorption. This damping function is first obtained by evaluating the empirical data of the optical constants and is then compared with an approximate computation based on the frequency spectrum of lattice vibrations. The result of this comparison shows that theory and experiment correspond qualitatively very closely, especially with respect to the secondary structure in dispersion.