The purpose of the proposed research is to identify and characterize persistent IR spectral effects in a variety of crystalline and disordered solids. The technique provides a high resolution window into defect dynamics and the local environment, measures the excited vibrational state dephasing time and probes the low lying non-equilibrium elastic configurations in both crystalline and disordered solids. Four different types of systems will be explored: 1) glass-like crystals will provide a new approach for studying low lying states in glasses; 2) the apparent strong interaction between persistent photodarkening and persistent IR hole burning in chalcogenide glasses; 3) whether glassy behavior in polymers translates into persistent spectroscopic effects; 4) whether the impurity-induced far IR spectrum associated with heavy metal impurities in alkali halides is persistent.
