Quantitative first-principles calculations of valence and core excitation spectra of solid C60

All-Electron many-body approach to resonant inelastic x-ray scattering

We present a formalism for the resonant inelastic x-ray scattering (RIXS) cross section. The resulting compact expression in terms of polarizability matrix elements, particularly lends itself to the implementation in...

Exciton-Dominated Core-Level Absorption Spectra of Hybrid Organic-Inorganic Lead Halide Perovskites

In a combined theoretical and experimental work, we investigate X-ray absorption near-edge structure spectroscopy of the I L₃ and the Pb M₅ edges of the methylammonium lead iodide (MAPbI₃) hybrid inorganic-organic perovskite and its binary phase PbI₂. The absorption onsets are dominated by bound excitons with sizable binding energies of a few hundred millielectronvolts and pronounced anisotropy. The spectra of both materials exhibit remarkable similarities, suggesting that the fingerprints of core excitations in MAPbI₃ are essentially given by its inorganic component, with negligible influence from the organic groups. The theoretical analysis complementing experimental observations provides the conceptual insights required for a full characterization of this complex material.