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arXiv · 2211.15892

Shape resonances in photoionization cross sections and time delay

Anatoli S. Kheifets·Stephen Catsamas
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Abstract

Shape resonances in photoionization of atoms and molecules arise from a particular geometry of the ionic potential which traps the receding photoelectron in a quasi-bound state in a particular partial wave. This mechanism allows us to connect the photoionization cross section in the resonant region with the photoelectron scattering phase in this partial wave by a simple formula $σ\propto \sin^2δ_\ell$. Due to this relation, the phase $δ_\ell$ can be extracted from an experimentally known cross section and then converted to the photoelectron group delay (Wigner time delay) $τ_{\rm W} = \partial δ_\ell/\partial E$ which is measurable by recently developed laser interferometric techniques. Such a direct connection of the photoionization cross section and the time delay is a fundamental property of shape resonances which provides a comprehensive test of novel measurements against a large body of older synchrotron data.

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Anatoli S. Kheifets, Stephen Catsamas. 2022-11-29. Shape resonances in photoionization cross sections and time delay. https://doi.org/10.1103/physreva.107.l021102

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