The electronic states of isoxazole studied by VUV absorption, electron energy-loss spectroscopies and ab initio multi-reference configuration interaction calculations

Isobel C. Walker, Michael H. Palmer, Jacques Delwiche, Søren V. Hoffmann, P. L. Vieora, Nigel J. Mason, Martyn F. Guest, Marie Jeanne Hubin-Franskin, J. Heinesch, A. Giuliani

Research output: Contribution to journalArticle

Abstract

The VUV absorption spectrum of isoxazole (5-10.8 eV, 250-115 nm) has been recorded for the first time. The molecule has also been probed using electron impact with electrons of different incident energies and the He(I) photoelectron spectrum has been re-measured. Electronic excitation energies for valence and Rydberg-type states have been computed using multi-reference multi-root CI methods. Calculated energies for Rydberg states are close to those expected, but the precision of the calculated 1pp* states is more variable, especially for the lowest members. More than 30 valence excited states having finite oscillator strengths are computed to lie between 6 and 12 eV, but most of the intensity in the VUV absorption spectrum is from excitation of states of 1pp* character. From the results of the calculations, it is concluded that the first two 1pp* states lie at about 6 and 7 eV, respectively, and are separated by a state of type 1sp*, where s is nitrogen lone pair; dominant higher bands near 8 and 9 eV are also largely 1pp* in character. The lowest-lying triplet states, located by experiment at about 4.1 eV and 5.3 eV, are calculated to be 3pp*. Short-lived anionic states (electron-molecule resonances) have been detected in both inelastic scattering and dissociative electron attachment channels. Some one-electron properties derived from the ground state wavefunction of the molecule have also been computed for comparison with experiment. © 2003 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)289-306
Number of pages18
JournalChemical Physics
Volume297
Issue number1-3
DOIs
Publication statusPublished - 16 Feb 2004

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configuration interaction
energy dissipation
electron energy
electronics
spectroscopy
excitation
valence
absorption spectra
molecules
electron attachment
electron states
oscillator strengths
atomic energy levels
electron impact
energy
inelastic scattering
photoelectrons
electrons
nitrogen
ground state

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Walker, Isobel C. ; Palmer, Michael H. ; Delwiche, Jacques ; Hoffmann, Søren V. ; Vieora, P. L. ; Mason, Nigel J. ; Guest, Martyn F. ; Hubin-Franskin, Marie Jeanne ; Heinesch, J. ; Giuliani, A. / The electronic states of isoxazole studied by VUV absorption, electron energy-loss spectroscopies and ab initio multi-reference configuration interaction calculations. In: Chemical Physics. 2004 ; Vol. 297, No. 1-3. pp. 289-306.
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abstract = "The VUV absorption spectrum of isoxazole (5-10.8 eV, 250-115 nm) has been recorded for the first time. The molecule has also been probed using electron impact with electrons of different incident energies and the He(I) photoelectron spectrum has been re-measured. Electronic excitation energies for valence and Rydberg-type states have been computed using multi-reference multi-root CI methods. Calculated energies for Rydberg states are close to those expected, but the precision of the calculated 1pp* states is more variable, especially for the lowest members. More than 30 valence excited states having finite oscillator strengths are computed to lie between 6 and 12 eV, but most of the intensity in the VUV absorption spectrum is from excitation of states of 1pp* character. From the results of the calculations, it is concluded that the first two 1pp* states lie at about 6 and 7 eV, respectively, and are separated by a state of type 1sp*, where s is nitrogen lone pair; dominant higher bands near 8 and 9 eV are also largely 1pp* in character. The lowest-lying triplet states, located by experiment at about 4.1 eV and 5.3 eV, are calculated to be 3pp*. Short-lived anionic states (electron-molecule resonances) have been detected in both inelastic scattering and dissociative electron attachment channels. Some one-electron properties derived from the ground state wavefunction of the molecule have also been computed for comparison with experiment. {\circledC} 2003 Elsevier B.V. All rights reserved.",
author = "Walker, {Isobel C.} and Palmer, {Michael H.} and Jacques Delwiche and Hoffmann, {S{\o}ren V.} and Vieora, {P. L.} and Mason, {Nigel J.} and Guest, {Martyn F.} and Hubin-Franskin, {Marie Jeanne} and J. Heinesch and A. Giuliani",
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Walker, IC, Palmer, MH, Delwiche, J, Hoffmann, SV, Vieora, PL, Mason, NJ, Guest, MF, Hubin-Franskin, MJ, Heinesch, J & Giuliani, A 2004, 'The electronic states of isoxazole studied by VUV absorption, electron energy-loss spectroscopies and ab initio multi-reference configuration interaction calculations', Chemical Physics, vol. 297, no. 1-3, pp. 289-306. https://doi.org/10.1016/j.chemphys.2003.10.012

The electronic states of isoxazole studied by VUV absorption, electron energy-loss spectroscopies and ab initio multi-reference configuration interaction calculations. / Walker, Isobel C.; Palmer, Michael H.; Delwiche, Jacques; Hoffmann, Søren V.; Vieora, P. L.; Mason, Nigel J.; Guest, Martyn F.; Hubin-Franskin, Marie Jeanne; Heinesch, J.; Giuliani, A.

In: Chemical Physics, Vol. 297, No. 1-3, 16.02.2004, p. 289-306.

Research output: Contribution to journalArticle

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T1 - The electronic states of isoxazole studied by VUV absorption, electron energy-loss spectroscopies and ab initio multi-reference configuration interaction calculations

AU - Walker, Isobel C.

AU - Palmer, Michael H.

AU - Delwiche, Jacques

AU - Hoffmann, Søren V.

AU - Vieora, P. L.

AU - Mason, Nigel J.

AU - Guest, Martyn F.

AU - Hubin-Franskin, Marie Jeanne

AU - Heinesch, J.

AU - Giuliani, A.

PY - 2004/2/16

Y1 - 2004/2/16

N2 - The VUV absorption spectrum of isoxazole (5-10.8 eV, 250-115 nm) has been recorded for the first time. The molecule has also been probed using electron impact with electrons of different incident energies and the He(I) photoelectron spectrum has been re-measured. Electronic excitation energies for valence and Rydberg-type states have been computed using multi-reference multi-root CI methods. Calculated energies for Rydberg states are close to those expected, but the precision of the calculated 1pp* states is more variable, especially for the lowest members. More than 30 valence excited states having finite oscillator strengths are computed to lie between 6 and 12 eV, but most of the intensity in the VUV absorption spectrum is from excitation of states of 1pp* character. From the results of the calculations, it is concluded that the first two 1pp* states lie at about 6 and 7 eV, respectively, and are separated by a state of type 1sp*, where s is nitrogen lone pair; dominant higher bands near 8 and 9 eV are also largely 1pp* in character. The lowest-lying triplet states, located by experiment at about 4.1 eV and 5.3 eV, are calculated to be 3pp*. Short-lived anionic states (electron-molecule resonances) have been detected in both inelastic scattering and dissociative electron attachment channels. Some one-electron properties derived from the ground state wavefunction of the molecule have also been computed for comparison with experiment. © 2003 Elsevier B.V. All rights reserved.

AB - The VUV absorption spectrum of isoxazole (5-10.8 eV, 250-115 nm) has been recorded for the first time. The molecule has also been probed using electron impact with electrons of different incident energies and the He(I) photoelectron spectrum has been re-measured. Electronic excitation energies for valence and Rydberg-type states have been computed using multi-reference multi-root CI methods. Calculated energies for Rydberg states are close to those expected, but the precision of the calculated 1pp* states is more variable, especially for the lowest members. More than 30 valence excited states having finite oscillator strengths are computed to lie between 6 and 12 eV, but most of the intensity in the VUV absorption spectrum is from excitation of states of 1pp* character. From the results of the calculations, it is concluded that the first two 1pp* states lie at about 6 and 7 eV, respectively, and are separated by a state of type 1sp*, where s is nitrogen lone pair; dominant higher bands near 8 and 9 eV are also largely 1pp* in character. The lowest-lying triplet states, located by experiment at about 4.1 eV and 5.3 eV, are calculated to be 3pp*. Short-lived anionic states (electron-molecule resonances) have been detected in both inelastic scattering and dissociative electron attachment channels. Some one-electron properties derived from the ground state wavefunction of the molecule have also been computed for comparison with experiment. © 2003 Elsevier B.V. All rights reserved.

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