THE OPTICAL CONSTANTS OF SOME IONIC SOLIDS IN THE NEIGHBORHOOD OF THEIR $EIGENFREQUENCIES^{*}$

Abstract

“The transmission of thin films of several ionic solids have been measured for several film thicknesses and two temperatures. The solids (LiF, NaCl, NaBr, KCl, KBr, and KI) were deposited on a collodion substrate and measured with a grating spectrometer which was well filtered to insure purity of the measured radiation. By assuming the wavelength dependence of the optical constants n and k to be correctly expressed by the classical formulae, it was possible to obtain the values of n and k through the eigenfrequency region. The results will be compared with those of other workers and the temperature shift of the eigenfrequencies will be discussed.”