Studies of Phonon-Photon and Electron-Photon Interaction via Incoherent Nuclear Resonant Scattering of Synchrotron Radiation

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9623684 Mullen This proposal is intended to develop capabilities for meV resolution xray optics that can be used to scan the phonon density of states using the Mossbauer transitions with energies below 30 keV. The technique, which has so far been applied only to 57Fe, will permit the measurement of the density of phonon states for europium and dysprosium compounds. We plan to explicitly carry out such measurements on the high Tc superconductors, as well as multilayer semiconductors containing europium. Using delayed coincidence techniques we propose to measure low-angle Compton scattering, to obtain new information about the Fermi surface of metals. %%% Gamma and x-ray optics is at the forefront of synchrotron radiation. We propose a new two crystal system of x-ray optics that should enhance the energy resolution of synchrotron monochromators by an order of magnitude. This improved technology will make possible precision density of states measurements of lattice vibrations in solids and new approaches to determining the electronic properties of crystalline materials. These techniques will be applied to high temperature superconductors, superlattice semiconductors structures, and especially to crystalline materials that can only be fabricated in millimeter sizes where neutron scattering measurements are not practical. ***