Inelastic nuclear resonant scattering with sub-meV energy resolution

With an undulator-based synchrotron source and a tunable x-raf monochromator, we produce an x-ray beam with a flux of 4X10(8) photons/s in an energy bandwidth of 920+/-110 mu eV (Delta E/E approximate to 6.2X10(-8)) at a photon energy of 14.4 keV. The tunability of the monochromator allows for a measurement of lattice excitations in alpha-Fe using the technique of inelastic nuclear resonant scattering from Fe-57. The phonon density-of-states are extracted from the measurement and compared to the calculated phonon density-of-states derived from neutron-scattering measurements. (C) 1997 American Institute of Physics.