STRUCTURE AND DYNAMICS IN SOLIDS AS PROBED BY OPTICAL SPECTROSCOPY

Optical spectroscopy provides a useful tool for probing the structure and dynamics of solids. Over the years, optical methods have evolved f rom absorption spectroscopy to more complex methods such as spectral h ole burning, photon echoes, and luminescence line narrowing. The absor ption spectrum provides information about inhomogeneous broadening, wh ile the latter approaches provide information about the systematics of the homogeneous line shape-information that is often obscured by inho mogeneous broadening. When external perturbations such as strain or el ectric fields are applied, details of the local site can be obtained. Recently, the ultimate limit of optical spectroscopy has been attained , in which the spectral properties of individual single impurity molec ules in a solid can be measured, with all ensemble averaging removed. This novel regime has provided additional, previously unobtainable, in formation on a highly local scale, such as the direct observation of t he spectral shifting of a single molecule produced by configurational transitions of the host. It is to be expected that further surprises a wait us in this new frontier of single-molecule spectroscopy in solids .