Effect of vibrations on the pre-edge features of x-ray absorption spectra

Abstract

The influence of atomic vibrations on x-ray absorption near edge structure (XANES) is calculated by assuming that vibrational energies are small with respect to the instrumental resolution. The resulting expression shows that, at the K-edge, vibrations enable electric dipole transitions to 3s and 3d final states. The theory is applied to the K-edge of Al in Al2O3 corundum and of Ti in TiO2 rutile and compared with experiment. At the Al K-edge, sizeable transitions towards 3s final states are obtained, leading to a clear improvement of the agreement with experimental spectra. At the Ti K-edge, electric dipole transitions towards 3d final states explain the temperature dependence of the pre-edge features.

4 pages, 2 figures

References in corpus (3)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• X-ray Absorption Near-Edge Structure calculations with pseudopotentials. Application to K-edge in diamond and alpha-quartz
• Theoretical X-Ray Absorption Debye-Waller Factors

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• Pseudopotential Bethe-Salpeter calculations for shallow-core x-ray absorption near-edge structures: excitonic effects in Al2O3
• Effect of lattice excitations on transient near edge X-ray absorption spectroscopy