Atoms (Oct 2020)

Vibrationally and Spin-Orbit-Resolved Inner-Shell X-ray Absorption Spectroscopy of the NH<sup>+</sup> Molecular Ion: Measurements and ab Initio Calculations

  • Stéphane Carniato,
  • Jean-Marc Bizau,
  • Denis Cubaynes,
  • Eugene T. Kennedy,
  • Ségolène Guilbaud,
  • Emma Sokell,
  • Brendan McLaughlin,
  • Jean-Paul Mosnier

DOI
https://doi.org/10.3390/atoms8040067
Journal volume & issue
Vol. 8, no. 4
p. 67

Abstract

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This article presents N2+ fragment yields following nitrogen K-shell photo-absorption in the NH+ molecular ion measured at the SOLEIL synchrotron radiation facility in the photon energy region 390–450 eV. The combination of the high sensitivity of the merged-beam, multi-analysis ion apparatus (MAIA) with the high spectral resolution of the PLEIADES beamline helped to resolve experimentally vibrational structures of highly excited [N1s−1H]*+ electronic states with closed or open-shell configurations. The assignment of the observed spectral features was achieved with the help of density functional theory (DFT) and post-Hartree Fock Multiconfiguration Self-Consistent-Field/Configuration Interaction (MCSCF/CI) ab-initio theoretical calculations of the N1s core-to-valence and core-to-Rydberg excitations, including vibrational dynamics. New resonances were identified compared to previous work, owing to detailed molecular modeling of the vibrational, spin-orbit coupling and metastable state effects on the spectra. The latter are evidenced by spectral contributions from the 4Σ− electronic state which lies 0.07 eV above the NH+2Π ground state.

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