Regular Article

Electron impact ionisation cross sections of iron oxides^★

¹ Institute of Ion Physics and Applied Physics, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
² Institute for Basic Sciences in Engineering Science, University of Innsbruck, Technikerstraße 13, 6020 Innsbruck, Austria
³ Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, 84248 Bratislava, Slovakia
⁴ Vidyasirimedhi Institute of Science and Technology, School of Energy Science and Engineering, 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand

^a e-mail: s.huber@uibk.ac.at

Received: 6 May 2017
Received in final form: 26 September 2017
Published online: 19 December 2017

Abstract

We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, Fe_xO_x and Fe_xO_x+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9 . 96 × 10^-16 cm² located at 59–72 eV and 5.06 to 14.32 × 10^-16 cm² located at 85–108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4–1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research.