Shape resonances in the photoionization of N_2O

Abstract

We report the results of studies of the cross sections and photoelectron asymmetry parameters for photoionization of the 7σ level of N_2O using Hartree–Fock photoelectron continuum orbitals. These studies were motivated by recent measurements which showed significant non‐Franck–Condon vibrational distributions at low photoelectron energies where previously only autoionizing resonances, but no shape resonance, had been identified. Our results establish that there are two σ shape resonances in the 7σ ionization continuum, a pronounced resonance at low photoelectron energies, and another at higher energy which is essentially obscured in the vibrationally unresolved cross sections. The shape resonant structure that emerges from these studies differs significantly from the predictions of previous model studies. Studies in progress reveal a rich and unusual dependence of these resonances on changes in internuclear distances.

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