We present a joint theoretical and experimental investigation of the N 1s photoionization of NO2 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(1)-->B-2 transition and that the shape resonance energy of the N 1s(-1) (1)A(1) channel is about 2.6 eV lower in kinetic energy than that of the N 1s(-1) (3)A(1) channel, suggesting that the potential for the (1)A(1) channel is much more attractive than that for the (3)A(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(1)-->B-2 transition, as predicted by the calculation. The experimental partial cross sections for the N 1s(-1) (1)A(1) and (3)A(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 (1)A(1) channel is overestimated in the single-channel approximation. The possible role played by correlation effects on the K-shell ionization of NO2 is discussed in terms of interchannel coupling between the main-line channels and, possibly, with additional excited target states.

Symmetry- And multiplet-resolved N 1s photoionization cross sections of the NO2 molecule

TOFFOLI, DANIELE;
2004

Abstract

We present a joint theoretical and experimental investigation of the N 1s photoionization of NO2 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(1)-->B-2 transition and that the shape resonance energy of the N 1s(-1) (1)A(1) channel is about 2.6 eV lower in kinetic energy than that of the N 1s(-1) (3)A(1) channel, suggesting that the potential for the (1)A(1) channel is much more attractive than that for the (3)A(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(1)-->B-2 transition, as predicted by the calculation. The experimental partial cross sections for the N 1s(-1) (1)A(1) and (3)A(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 (1)A(1) channel is overestimated in the single-channel approximation. The possible role played by correlation effects on the K-shell ionization of NO2 is discussed in terms of interchannel coupling between the main-line channels and, possibly, with additional excited target states.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2870391
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