A computational analysis of low-energy electron scattering from gaseous cyclopropane

Abstract

Absolute elastic cross sections, integral and differential, are computed for electron-cyclopropane collisions at energies from 1.0 up to 15.0 eV, spanning the region where possible shape resonance structures were detected by earlier experiments and calculations. The present results confirm the above findings and locate a resonance of A2' symmetry around 6.0 eV and a broader, weaker resonance of A2'' symmetry around 8 eV. The calculations are further shown to be in good agreement with the existing measurements of the angular distributions of the scattered electrons at energies from 2.0 up to 10.0 eV. The presently computed cross sections also agree with earlier R-matrix calculations (Beyer T, Nestmann B M, Sarpal B K and Peyerimhoff S D 1997 J. Phys. B: At. Mol. Opt. Phys. 30 3431) and with the available integral cross section measurements. A model local exchange potential of very simple usage is shown to provide quite good accord with the exact calculations at the static-exchange level.

Experimental and theoretical elastic cross sections for electron collisions with the C3H6 isomers

“…This does not occur with the results of Curik and Gianturco ͑who use a single center expansion, and are thus able to account for the higher partial waves͒, which agree with the experiment at all angles of overlap. However, the current experimental and theoretical results are found to agree well both qualitatively and quantitatively at overlapping energies at 7 eV and above with all three theoretical 6,21,22 and one experimental result. 23 These results are summarized as follows.…”

“…However, at this region, the current theoretical result seems to agree well with the other theoretical results by Winstead et al 6 ͑both calculations done with the SMC method͒ and Beyer et al, 21 whereas the two experimental results agree between themselves, as well as with the theoretical result by Curik and Gianturco. 22 In the SMC method, the scattering wave function is expanded in a basis set formed by square integrable functions ͑L 2 functions͒; the…”

“…Quantum calculations were carried out too in the investigation of a number of the vibrational modes. 20 Elastic DCS for these molecules have been studied mainly theoretically, 6,21,22 although there exists, to our knowledge, also one measurement. 23 High-resolution electron-energy-loss spectroscopy experiments were employed to study singlet-triplet, inner-shell, and valence-shell electronic excitations, of these molecules, [24][25][26] while photoabsorption and photoelectron spectra were also studied and helped in establishing the electronic states for these molecules.…”

Electron-impact vibrational excitation of cyclopropane

“…Present calculations are shown as red line, while the orange line represents previous SMC, 40 and blue line represents results of single-center expansion method. 42 The oldest SMC results 43 are omitted here for clarity reasons.…”

“…40 The red line shows present calculations, blue line displays results of previous Schwinger multi-channel calculations, 40 and the green line represents single-center expansion calculations. 42 may be assigned to the use of a single (electronic) channel model. Since the ionization potential of cyclopropane is at about 10 eV 45 and the lowest excited electronic states start at about 6.3 eV, 46 multiple electronic channels, not accounted for by single channel approach, become open.…”