The Bicarbonate Ion in Solid Solution in Alkali Halides: An Optical Filter at 10.6 μm

Abstract

When single impurity ions go into solid solution in alkali halide crystals, very narrow absorption bands appear in the infrared spectra of these materials. These narrow bands arise from the isolation of the individual impurity ions in the crystal lattice. Such bands have a bandwidth of 2 to 6 cm−1 at room temperature and 0.5 to 2.0 cm−1 at liquid nitrogen temperature. The frequency of the band shifts 2 to 4 cm−1 higher at liquid nitrogen temperature.