Double-core Excitations in Formamide Can Be Probed by X-ray Double-quantum-coherence Spectroscopy

TL;DR

This paper demonstrates how X-ray double-quantum-coherence spectroscopy can probe double-core excitations in formamide, revealing electron correlation effects and testing electronic structure theories through simulated signals.

Contribution

It introduces a simulation approach using REW-TDDFT and XCH to study core exciton coupling in formamide's K-edges, highlighting sensitivity to electron correlation treatments.

Findings

XDQC signals are sensitive to electron correlation levels.

Core exciton coupling influences the spectral signals.

Simulations provide signatures of many-body effects in core holes.

Abstract

The attosecond, time-resolved X-ray double-quantum-coherence (XDQC) four wave mixing signals of formamide at the nitrogen and oxygen K-edges are simulated using restricted excitation window time-dependent density functional theory (REW-TDDFT) and the excited core hole (XCH) approximation. These signals, induced by core exciton coupling, are particularly sensitive to the level of treatment of electron correlation, thus providing direct experimental signatures of electron core hole many-body effects and a test of electronic structure theories.