Kavli Affiliate: Scott K. Cushing
| First 5 Authors: Isabel M. Klein, Alex Krotz, Jonathan M. Michelsen, Scott K. Cushing,
| Summary:
Transient X-ray spectroscopies have become ubiquitous in studying
photoexcited dynamics in solar energy materials due to their sensitivity to
carrier occupations and local chemical or structural dynamics. The
interpretation of solid-state photoexcited dynamics, however, is complicated by
the core-hole perturbation and the resulting many-body dynamics. Here, an ab
initio, Bethe-Salpeter equation (BSE) approach is developed that can
incorporate photoexcited state effects for solid-state materials. The extreme
ultraviolet (XUV) absorption spectra for the ground, photoexcited, and
thermally expanded states of first row transition metal oxides – $TiO_2,
alpha-Cr_2O_3, beta-MnO_2, alpha-Fe_2O_3, Co_3O_4, NiO, CuO, and ZnO$ – are
calculated to demonstrate the accuracy of this approach. The theory is used to
decompose the core-valence excitons into the separate components of the X-ray
transition Hamiltonian for each of the transition metal oxides investigated.
The decomposition provides a physical intuition about the origins of XUV
spectral features as well as how the spectra will change following
photoexcitation. The method is easily generalized to other K, L, M, and N edges
to provide a general approach for analyzing transient X-ray absorption or
reflection data.
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