Transient Optical Studies of Non-equilibrium Excitations in Semiconductors and Energy Transfer Processes in Ionic Crystals

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9301100 Tsen This experimental program will study the dynamics of carriers in semiconductors under extreme non-equilibrium conditions. A second sub-project will investigate energy transfer processes in ionic crystals. Sub-picosecond time-resolved Raman spectroscopy will be used to examine carrier transport under electic fields. The technique provides a direct, simple interpretation of the experimental results, which will provide conclusive fundamental information on ballistic transport as well as velocity overshoot phenomena predicted theoretically in nanostructured semiconductors. Study of various energy transfer processes in ionic crystals by time-resolved Raman spectroscopy should provide direct information about vibrational-to-vibrational energy transfer processes in a model solid state system. %%% This experimental program will study the dynamics of semiconductor electrons moving under the influence of high electric fields. A second project will investigate how energy is transferred among the various modes of vibration in an ionic crystal when it absorbs light. The information is of fundamental significance and is also of technological significance. It will aid in the design of better and faster semiconductor devices of micron and submicron dimensions. The energy transfer processes are immediately relevant to the design and utility of far infrared lasers used in photonics and telecommunications applications. ***