ON THE MECHANISM OF NONPHOTOCHEMICAL HOLE BURNING OF OPTICAL-TRANSITIONS IN AMORPHOUS SOLIDS

New temperature-dependent nonphotochemical hole burning results are reported for cresyl violet perchlorate in polyvinyl alcohol which indicate that the simple model for spectral hole production based on a static distribution of two-level systems (TLS) provides an inadequate description. One of the key observations reported is noted to have been made for a variety of other systems. A new mechanism, based on an "outside-in" hierarchy of constrained configurational tunneling events, is proposed in which the time evolution of free volumes plays an important role. The model is consistent with the available data and lends itself to testing by further experiments. © 1990.