Dynamic screening of the core exciton by swift electrons in electron-energy-loss scattering

We show for the first time that electron-energy-loss measurements of atomic absorption are different from the soft-x-ray photoyield data in the region influenced by the core exciton. We suggest that the core-exciton envelope function is influenced by the swift electron and its associated charge-density wake. Solving Schr\"odinger's equation for a model transition potential including the swift electron, we find that the observed differences for SiOₓ, diamond, and Si can be reproduced. Spectra from aluminum are included as a comparison when the exciton is absent.