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Verhandlungen
Verhandlungen
DPG

Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 33: New materials

HL 33.1: Vortrag

Mittwoch, 28. März 2007, 16:45–17:00, H15

Study of the Ba giant dipole resonance in Ba8Si46 with non-resonant inelastic x-ray scattering — •Sternemann Henning1, Sternemann Christian1, Tse John S.2, Desgreniers Serge3, Vankó György4, Schacht Andreas1, Soininen Juha Aleksi5, and Tolan Metin11Dept. Phys. / DELTA, University of Dortmund, D-44221 Dortmund — 2Dept. Phys. & Engn. Phys., University of Saskatchewan, Canada — 3Dept. Phys., University of Ottawa, Canada — 4ESRF, Grenoble, France — 5Div. X-ray Physics, Dept. Physical Sciences, University of Helsinki, Finland

Atomic Ba shows a giant dipole resonance arising from collective 4d electron motion above the energetic threshold of the NIV,V edges. We will present the first experimental observation of the Ba resonance in the complex silicon clathrate network of Ba8Si46. The measurements were done at different momentum transfers using non-resonant inelastic x-ray scattering. The giant resonance spectra were modeled within the time-dependent local density approximation using a real-space multiple-scattering approach. The resulting spectra show very good agreement with the experiment. Separate calculations for Ba@Si20 and Ba@Si24 demonstrate the sensitivity of the resonance concerning the local environment of the Ba atom. Thus, a combined study of absorption edges and the fine-structure of the giant resonance by means of non-resonant inelastic x-ray scattering yields the possibility to study electronic and structural changes in pressure-induced phase transitions of the clathrate simultanously. The experimental setup for such studies will also be presented.

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