Electron impact ionization dynamics of para-benzoquinone

Abstract

Triple differential cross sections (TDCSs) for the electron impact ionization of the unresolved combination of the 4 highest occupied molecular orbitals (4b, 5b, 1b, and 2b) of para-benzoquinone are reported. These were obtained in an asymmetric coplanar geometry with the scattered electron being observed at the angles -7.5°, -10.0°, -12.5° and -15.0°. The experimental cross sections are compared to theoretical calculations performed at the molecular 3-body distorted wave level, with a marginal level of agreement between them being found. The character of the ionized orbitals, through calculated momentum profiles, provides some qualitative interpretation for the measured angular distributions of the TDCS.

Total electron scattering cross sections from para-benzoquinone in the energy range 1–200 eV

“…Note that this energy is near to the pBQ threshold ionisation energy (10.0 ± 0.1 eV) 13 and our calculation, which is based on the atomic ionisation energies, is not able to properly reproduce near-threshold molecular scattering processes. However, from 12 eV and above our calculated total ionisation and total excitation cross sections agree well with our previous BEB calculation and experimental total electronic-state excitation cross sections.…”

“…Low-energy dissociative electron interactions have been reviewed by Ómarsson and Ingólfsson, 6 while electronic excitation and ionisation processes have been studied by several different authors. 2,3,[7][8][9][10][11][12][13][14][15] Electron attachment processes have also been experimentally studied and some resonances identified, 16,17,18,19 with some of those resonances having recently been investigated through R-matrix 20 and "ab initio" electronic structure calculations of the p-BQ anion. 21,22 More recently, we have combined theoretical and experimental photoabsorption techniques to investigate the electronic excitedstate structure of pBQ, and their corresponding electron scattering cross sections, together with some elastic differential cross section calculations.…”

An experimental and theoretical investigation into the electronically excited states of para-benzoquinone

“…Further, the dynamics of the electron impact ionization of pBQ have been recently investigated. 32 In the present contribution, we report a high resolution synchrotron photoabsorption spectrum of pBQ. This is complemented by new electron energy loss spectra (EELSs) measurements.…”

Electron-impact electronic-state excitation of para-benzoquinone

“…The spectroscopy of quinones has therefore attracted considerable attention over an extended period, with comprehensive reviews by Itoh 3 and more recently bý Omarsson and Ingólfsson. 4 While the electronic-state spectroscopy is complicated by a large number of closely lying (in energy) states, photo-, chemi-, and electron-impact ionization [5][6][7][8][9][10][11] investigations have helped to clarify the ordering of orbitals in the neutral species and its cationic structure. The anion states of pBQ and quinone derivatives have also been heavily studied, particularly through dissociative and non-dissociative electron attachment and electron scattering resonances.…”