R. Lai et al., SPECTRAL SIGNATURE OF LOW-TEMPERATURE HOPPING BETWEEN 2 IMPURITY-INDUCED ELASTIC CONFIGURATIONS, Physical review letters, 76(11), 1996, pp. 1864-1867
We demonstrate that the jump-rotational-diffusion model originally dev
eloped in the context of quasielastic neutron scattering from high tem
perature liquids can describe the two-state behavior observed in the l
ow temperature dynamics of some molecular and point defects in crystal
s. The unusual temperature dependences of the IR spectra of both diato
mic chalcogen hydrides in alkali halides and KI:Ag+ can be explained i
n terms of two elastic configurations between which the impurities jum
p with temperature-dependent dwell times.