Multiple-electron excitation in X-ray absorption: a screened model of the core-hole-photoelectron potential

The probability of secondary electron shake-off in X-ray absorption is calculated using a model form for the time- and energy-dependent core-hole-photoelectron potential, screened by the single plasmon pole dielectric function of the surrounding material. The resultant excitation probabilities are related to the energy-dependent intrinsic loss function in EXAFS data analysis and compared with experiment. Reasonable agreement is obtained close to the absorption edge although the calculation is less accurate at higher photon energies. The theory described allows the losses to be calculated with little computational effort, making the method suitable for routine EXAFS data analysis.