Non-photochemical hole burning and impurity site relaxation processes in organic glasses

Laser-induced holes in the inhomogeneously broadened absorption spectra of aromatic hydrocarbons in frozen glasses are reported. The holes are shown to be of non-photochemical origin. Mechanisms for excited state site interconversion based on a metastable distribution of sites in asymmetric double well potentials are presented. Methods of eliminating non-photochemical holes and of distinguishing between photochemical and non-photochemical holes are described.