The dynamic conductivity and the plasmon profile of Aluminum in the ultra-fast-matter regime; an analysis of recent X-ray scattering data from the LCLS

Abstract

We use an explicitly isochoric two-temperature theory where the ion temperature is not assumed to be equal to the electron temperature, to analyze recent X-ray laser scattering data for Aluminum in the ultra-fast-matter (UFM) regime up to 6 eV, obtained at the Standford Linac Coherent Light Source (LCLS). The observed surprisingly low conductivities are explained by including strong electron-ion scattering effects using the phase shifts calculated via the density-functional neutral-pseudo-atom model (NPA). The applicability of the Mermin model to UFM is questioned. The static and dynamic conductivity, complex collision frequency and the plasmon line-shape are evaluated within a Born approximation and without the use of the Mermin response. This approach, where all needed quantities are obtained from the NPA model, provides good agreement with the reported experimental results.