Shakeup in soft-x-ray emission. I. The low-energy tail

Abstract

The L soft-x-ray emission spectra for Al and Si, and the K emission for graphite and diamond are analyzed, taking into account the effects of multielectron transitions which produce a low-energy tail on the main band. Through an appropriate transformation on the initial states, it is shown that the final-state rule of Von Barth and Grossman is a direct result of exchange. A ``Pauli rigidity'' forces the initial-state wave function to approach that of the final state, except near the Fermi energy. An assumption of random phases allows a formal solution that includes single-particle shakeup events to all orders. It is argued that a low-energy feature of silicon is structure due to the shakeup of single-particle-like excitations rather than a plasmon satellite.