Dresden 2011 – scientific programme

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KR: Fachgruppe Kristallographie

KR 6: Poster: Crystallography in Materials Science

KR 6.3: Poster

Wednesday, March 16, 2011, 15:00–17:30, P1

Polarization dependent Diffraction Anomalous Fine Structure studies of TiO₂. — •Carsten Richter^1,2, Matthias Zschornak¹, Dmitri Novikov², Hartmut Stöcker¹, and Dirk C. Meyer¹ — ¹Institute of Experimental Physics, TU Bergakademie Freiberg, Germany — ²Hamburger Synchrotronstrahlungslabor HASYLAB at DESY, Germany

Diffraction Anomalous Fine Structure (DAFS) is, like X-Ray Absorption Fine Structure (XAFS), a method suitable to study the local electronic structure of a certain type of atoms in the crystal. In contrast to absorption spectroscopy atoms of the same type but different crystallographic sites can be distinguished, due to the combination of spectroscopy and diffraction. Near an absorption edge, the atomic scattering factor becomes dependent of the polarization and direction of the incident and the reflected beam. Reflection conditions based on the crystal’s symmetry can be used to eliminate polarization or direction independent parts. This and the variation of the polarization with respect to the crystal allows a closer insight into the types of electronic transitions involved in the scattering process.

Here we present a detailed DAFS study of rutile single crystals with different densities of oxygen vacancies including measurements and modeling of the energy and polarization dependence of the scattered intensity. Recent results of its separation into the 2 polarization states using a polarization analyzer are included. The measurements have been carried out for rutile reflections 001 and 111 at beam lines C, E2 and W1 of the HASYLAB at DESY.