Postcollision-interaction recapture of photoelectrons and zero-kinetic-energy electron emission: A quantum model

Abstract

Near-threshold photoelectron recapture due to postcollision interaction with a single Auger electron is examined within the quantum-mechanical framework of radiationless resonant Raman scattering. Model calculations using a hydrogenic approximation are performed, revealing general features of the escape probability as a function of inner-shell decay width \ensuremath{\Gamma}. The escape probability is useful in estimating diagram and spectator Auger intensities near threshold. The process of recapture produces a delay in the onset of double ionization to energies above threshold, which scales as ${\ensuremath{\Gamma}}^{2/3}.$ The present model is also applied to the cross section for ejection of photoelectrons with zero kinetic energy (ZKE), assuming a stable final state. A comparison with semiclassical results at small \ensuremath{\Gamma} suggests that existing semiclassical distributions are formally correct, with further convolution suggested by Thomas et al. [J. Phys. B 29, 3245 (1996)] not required. Results of the present quantum ZKE model, which does not include additional cascade effects, are in agreement with existing data. Quantities that describe the escape and ZKE-emission distributions are identified and their variation with \ensuremath{\Gamma} is examined.