Momentum-dependent lifetime broadening of electron energy loss spectra: Sum rule constraints and an asymmetric rectangle toy model

Abstract

Electron energy loss spectra enable a detailed quantification of the electronic loss mechanisms in a target solid, particularly in the low-energy region dominated by plasmon excitations. Models of the electronic response in condensed-matter systems are usually derived from free-electron gas or jellium models, which commonly neglect to account for the lifetime broadening of individual plasmon and single-electron excitations in a constrained, physical manner. This can lead to potentially significant errors in electron energy loss spectra and electron inelastic mean-free-path (IMFP) calculations. We develop a toy model of plasmon and single-electron excitations that incorporates lifetime broade..