This research project utilizes laser spectroscopy techniques to investigate fundamental physical processes in inorganic host crystals doped with transition metal and rare earth ions. The processes to be studied include energy migration among the ions and radiationless relaxation transitions. The experimental techniques to be employed include four-wave mixing, accumulated photon echos, and pulse-probe transient absorption experiments. An effort will be made to verify a detailed model for the origin of the four-wave mixing signal of ions in solids, in addition to characterizing the energy migration between these ions in solids. The measurements will feature real time measurements in the subpicosecond regime. Uniaxial stress measurements will also be employed. It is hoped to learn more about the poorly understood processes associated with radiationless relaxation among the excited states of the ions in solids.
