Experimental signatures of phase interference and subfemtosecond time dynamics on the incident energy axis of resonant inelastic x-ray scattering

Core hole resonance is used in x-ray spectroscopy to incisively probe the local electronic states of many-body systems. Here, resonant inelastic x-ray scattering (RIXS) is studied as a function of incident photon energy on Mott insulators SrCuO2 and NiO to examine how resonance states decay into different excitation symmetries at the transition-metal M, L, and K edges. Quantum interference patterns characteristic of the two major RIXS mechanisms are identified within the data, and used to distinguish the attosecond scale scattering dynamics by which fundamental excitations of a many-body system are created. A function is proposed to experimentally evaluate whether a particular excitation has constructive or destructive interference in the RIXS cross section, and corroborates other evidence that an anomalous excitation is present at the leading edge of the Mott gap in quasi-one-dimensional SrCuO2.