Theoretical Treatments of the Bound-Free Contribution and Experimental Best Practice in X-ray Thomson Scattering from Warm Dense Matter

Abstract

By comparison with high-resolution synchrotron x-ray experimental results, we assess several theoretical treatments for the bound-free (core-electron) contribution to x-ray Thomson scattering (i.e., also known as nonresonant inelastic x-ray scattering). We identify an often overlooked source of systematic error in the plane- wave form factor approximation (PWFFA) used in the inference of temperature, ionization state, and free electron density in some laser-driven compression studies of warm dense matter. This error is due to a direct violation of energy conservation in the PWFFA. We propose an improved practice for the bound-free term that will be particularly relevant for XRTS experiments performed with somewhat improved energy resolution at the National Ignition Facility or the Linac Coherent Light Source. Our results raise important questions about the accuracy of state variable determination in XRTS studies, given that the limited information content in low-resolution XRTS spectra does not strongly constrain the models of electronic structure being used to fit the spectra.

References in corpus (5)

• Rocky core solubility in Jupiter and giant exoplanets
• High multipole transitions in NIXS: valence and hybridization in 4f systems
• Persistence of Covalent Bonding in Liquid Silicon Probed by Inelastic X-ray Scattering
• Thomson scattering in the average-atom approximation
• Exciton spectroscopy of hexagonal boron nitride using non-resonant x-ray Raman scattering

Cited by in corpus (4)

• First principles simulations of dense hydrogen
• X-ray Thomson scattering spectra from DFT-MD simulations based on a modified Chihara formula
• Modelling of warm dense hydrogen via explicit real time electron dynamics: Dynamic structure factors
• Real-Space Green's functions for Warm Dense Matter