Electron impact ionisation cross sections of iron oxides

Abstract

Abstract. We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+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 cm 2 located at 59-72 eV and 5.06 to 14.32 × 10 −16 cm 2 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.

The efficient calculation of electron impact ionization cross sections with effective core potentials

“…The Journal of Chemical Physics ARTICLE scitation.org/journal/jcp experiment. ECPs have been used previously in BEB calculations, [15][16][17] particularly for molecules of interest in nuclear fusion, [18][19][20] biologically significant molecules where electron impact ionization often plays a role in energy transfer mechanisms as a result of radiotherapy, 21,22 and molecules of interest for industrial plasma applications. 23,24 Our focus here is to make an implementation of ECPs for BEB as automated as possible to allow efficient generation of these cross sections for molecules containing heavy atoms.…”

Decomposition Reactions of Fe(CO)5, Fe(C5H5)2, and TTIP as Precursors for the Spray-Flame Synthesis of Nanoparticles in Partial Spray Evaporation at Low Temperatures

“…Direct calibration of the detected iron species is very difficult because these are not stable species, which can be bought and introduced into the mass spectrometer at known concentrations. The ionization cross section can be used for the atom of iron because the ionization cross section of iron has been calculated with good accuracy. − The estimation of the other cross sections requires quantum chemistry calculations as described in refs , . The reported experimental values , of the total ionization cross section of the iron atom vary between 3.75 × 10 –16 and 4.93 × 10 –16 cm 2 at the ionization energy of 20 eV.…”

“…The calculation predicts a value of 4.7 × 10 –16 cm 2 for the iron atom. A calculation for FeO estimates the cross section as 2 × 10 –16 cm 2 , whereas for FeH, this value is 3 × 10 –16 cm 2 . These values indicate that a transfer of ionization cross section from one iron-containing species to another is not permissible.…”

Electron impact ionisation cross sections of fluoro-substituted nucleosides

“…approach was followed sometimes in earlier work to estimate molecular cross sections from known atomic cross sections [56][57][58] which yields at least an upper bound for the real molecular cross sections. Improving the approximation, however, requires a refined approach [59].…”