Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 11: Elektronische Struktur I
O 11.4: Vortrag
Freitag, 4. März 2005, 16:30–16:45, TU EB420
Analysis of the SrTiO3 Valence Band Structure by X-ray Standing Wave Measurements and Ab-Initio Calculations — •Sebastian Thieß1, Tien-Lin Lee1, François Bottin2, Bruce C.C. Cowie1, and Jörg Zegenhagen1 — 1ESRF, Grenoble, France — 2CEA, Bruyères-le-Châtel, France
We have determined the Sr, Ti and O components of the SrTiO3 valence band (VB) by site-specific X-ray photoelectron spectroscopy employing the X-ray Standing Wave (XSW) method. Decomposition into angular-momentum resolved density of states for each element was achieved by comparision with ab initio calculations based on norm-conserving pseudopotentials within the local density approximation.
Lattice site-specific electronic information - which is not available from standard XPS - is obtained by utilising the spatial intensity modulation of an XSW interference field, generated by the coherent superposition of an incident and a Bragg-reflected x-ray beam. By proper positioning the antinodes of the XSW within the STO unit cell, photoemission from specific lattice sites can be preferentially excited and their valence electronic contribution identified.
XSW fields were generated by the STO(111) and STO(112) reflections at photon energies of 2.75 and 3.89 keV. XSW modulated, high-resolution core and valence-electron emission spectra were recorded from an in-situ UHV annealed STO single crystal at beamline ID32 at the ESRF.