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O: Fachverband Oberflächenphysik

O 42: Focus Session: Frontiers of Electronic-Structure Theory – Advances in Time-Dependent and Nonequilibrium Ab Initio Methods III

O 42.1: Talk

Wednesday, March 20, 2024, 10:30–10:45, HE 101

Pauli blocking and core-hole screening in X-ray transient absorption spectroscopy at the Zn K-edge in ZnO — •Lu Qiao¹, Thomas C. Rossi², Keith Gilmore¹, Renske M. Van der Veen², and Claudia Draxl¹ — ¹Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany — ²Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany

X-ray transient absorption (XTA) spectroscopy can provide valuable insight into the atomic structure, the electronic properties, and the dynamics of materials. Zinc oxide (ZnO) is a prototypical wide band gap band insulator with many applications in optoelectronics and photovoltaics. Combining state-of-the-art first principle calculations and picosecond XTA spectroscopy, we reveal XTA spectra at the Zn K-edge of ZnO thin films are composed of overlapping contributions from lattice heating and core-hole screening. In particular, we analyze the computed results obtained from the Bethe-Salpeter equation and time-dependent density functional theory to disentangle the contributions from Pauli blocking and core-hole screening. Our combined experimental and theoretical approach reveals that core-hole screening enhances with increasing excitation densities; its contribution to the XTA spectra dominates over Pauli blocking.

Keywords: X-ray transient absorption spectroscopy; Pauli blocking; Core-hole screening