Effect of Gamma Irradiation on Vibrational Spectra of KCl : TlNO_3 Crystals

摘要

Infrared absorption spectra of KCl : TlNO_3 crystals measured with a high-resolution spectrometer at 18 and 300 K are analyzed. Additional bands in the region of vibrations of nitrate ions at 18 K and at 300 K are detected after gamma irradiation. Models of NO_3~(2-), NO_3~-·Tl~+ centers and NO_3~- ions perturbed by oxygen defects are considered. Along with a fine structure of absorption spectra of nitrite and nitrate ions with the 3- to 6-cm~(-1) line separation observed at 18 K, a "hyperfine" structure with the 1-2 cm~(-1) line separation is revealed. This effect is explained by the superposition of vibrational absorption spectra of nitrite and nitrate ions whose vibrations are perturbed by defects that are not in the nearest environment. Gamma irradiation favors enhancement of lines of the hyperfine structure, probably, because of an increase in the concentration of defects.