Symmetry- and multiplet-resolved N1sphotoionization cross sections of theNO2molecule

Abstract

We present a joint theoretical and experimental investigation of the N 1s photoionization of NO{sub 2} in the shape resonance region. The theoretical calculations, based on a single-channel relaxed-core Hartree-Fock approximation, predict that the shape resonance appears only in the A{sub 1}{yields}B{sub 2} transition and that the shape resonance energy of the N 1s{sup -1} {sup 1}A{sub 1} channel is about 2.6 eV lower in kinetic energy than that of the N 1s{sup -1} {sup 3}A{sub 1} channel, suggesting that the potential for the {sup 1}A{sub 1} channel is much more attractive than that for the {sup 3}A{sub 1} channel. Symmetry-selected cross sections measured by means of a multiple-ion coincidence imaging prove that the shape resonance appears only in the A{sub 1}{yields}B{sub 2} transition, as predicted by the calculation. The experimental partial cross sections for the N 1s{sup -1} {sup 1}A{sub 1} and {sup 3}A{sub 1} channels measured by means of conventional electron spectroscopy exhibit the shape-resonance maxima at photon energies of 416.3 and 415.9 eV, respectively, at corresponding kinetic energies of 3.0 and 3.3 eV, respectively, implying that the attractive potential for the {sup 1}A{sub 1} channel is overestimated in the single-channel approximation. The possible role played by correlationmore » effects on the K-shell ionization of NO{sub 2} is discussed in terms of interchannel coupling between the main-line channels and, possibly, with additional excited target states.« less