Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 41: Postersitzung
M 41.44: Poster
Donnerstag, 27. März 2003, 14:30–16:30, HSZ
Moentum transfer dependence of inelastic x-ray Raman scattering from the Be K-edge — •Martin Schenkel1, C. Sternemann1, A. Soininen2,3, M. Paulus1, H. Nagasawa4, W. Schülke1 und M. Tolan1 — 1Institute of Physics, University of Dortmund, D-44221 Dortmund, Germany — 2Department of Physics, University of Washington, Seattle, Washington 98195, USA — 3Optical Technology Division, National Institute of Standards and Technology, Gaithsburg, Maryland 20899, USA — 4Faculty of Economics, Seikei University, Tokyo, 180-8633, Japan
We studied the Beryllium K-edge using non resonant x-ray Raman scattering at different momentum transfer q→, thus probing the unoccupied density of states. In addition we measured data for a Be polycrystal as well as for a single crystal with momentum transfer q→ both parallel and perpendicular to the c-axis, gaining acces to different symmetries of the final states of the excited electrons. The measurements have been carried out at the beamline SAW2 of the DELTA synchrotron.Energy loss spectra were measured at momentum transfers q=0.64 (1.27) a.u. where the dipole approximation is appropriate to discribe the excitation process so that 1s → p transitions dominate the x-ray Raman scattering cross section. By changing the scattering angle, q has been increased up to 4.78 a.u. making 1s → s transitions possible, resulting in a strong change in shape of the K-edge energy loss spectra.The spectra showed a distinct directional dependence for low momentum transfers, which vanished at higher q→. The experimental data are compared with first principles calculations modeling x-ray Raman scattering and its momentum dependence.