Electron collisons with cyclobutane

Abstract

We report integral, differential, and momentum transfer cross sections for elastic scattering of low-energy electrons by cyclobutane (c-C 4 H 8 ), which is an isomer of the C 4 H 8 molecule and has a closed chain. Our calculations were performed with the Schwinger multichannel method with pseudopotentials at the static-exchange level of approximation, for energies up to 50 eV. We compare the cross sections of cyclobutane with the cross sections of other three isomers of C 4 H 8 , namely, isobutene, cis-2-butene, and skew-1-butene. These isomers have open chain and were the subject of a previous study by our group [Lopes et al. J. Phys. B 37, 997 (2004)]. We also show previous calculated integral and momentum transfer cross sections for isomers of C 3 H 4 , C 3 H 6 and C 4 H 6 , which have open and closed chains. For each isomeric group we discuss the isomer effect focusing on the closed chain isomer. The isomer effect is related to differences in the isomers cross sections due to differences in their geometries.

Scattering of electrons from 1-butene, H2C=CHCH2CH3, and 2-methylpropene, H2C=C(CH3)2, molecules

“…Figure 3 confronts the present experimental TCS energy dependence for 1-butene with the TCS computations of Jiang et al (1995) and Tan et al (2010) and with the integral ECS calculations of Bettega et al (2006). Computations of Jiang et al (1995) carried out in the simple AR approximation lie above our experimental results over the whole common investigated energy range.…”

“…For the correction, however, the absolute differential cross sections (DCSs) are necessary, either from measurements or calculations, over the energies for which the TCS is determined. The only available electron-scattering DCSs for the C 4 H 8 isomers are the elastic data of Lopes et al (2004) and Bettega et al (2006) computed from 5 to 50 eV, within the SE level of approximation. With the aid of these DCS results and the collision cell geometry, we have estimated that the inability to discriminate against electrons scattered elastically through the small angles in the forward direction may lower our measured TCSs between 5-50 eV by about 2%, for both isomers.…”

“…Theoretical investigations on the electron collisions with 1-butene are more scarce. For instance, elastic cross sections (ECSs) were computed by Lopes et al (2004) and Bettega et al (2006) with the Schwinger multichannel method with pseudopotentials, at the staticexchange (SE) level of approximation, for incident energies up to 50 eV. The resulting elastic integral and MTCSs show two low-energy resonant structures: the sharp maximum in the vicinity of 3.8 eV and the broad enhancement centred around 12 eV.…”

“…The total cross section for the DEA process in 2-methylpropene as a function of electron impact energy was measured by Trepka and Neuert (1963) and Rutkowsky et al (1980). Theoretical works available in the literature (Lopes et al 2004, Bettega et al 2006 concern the elastic electron collisions with various butene isomers, among them the 2methylpropene, below 50 eV. The geometrical arrangement of constituents in the 2-methylpropene molecule was investigated with the gas electron diffraction (e.g.…”

Experimental and theoretical cross sections for positron scattering from the pentane isomers

“…Electronic mail: luca.chiari@rs.tus.ac.jp. (Kossoski et al, 2011), the hydrocarbons C 3 H 4 (Nakano et al, 2002;Szmytkowski and Kwitnewski, 2002b;Lopes and Bettega, 2003;Makochekanwa et al, 2003;Sanchez et al, 2005;, C 3 H 6 (Mott and Massey, 1965;Floeder et al, 1985;Nishimura and Tawara, 1991;Winstead et al, 1992;Szmytkowski and Kwitnewski, 2002a;Makochekanwa et al, 2005;2008;and Tan et al, 2007), C 4 H 6 Kwitnewski, 2003a andLopes et al, 2004a), C 4 H 8 (Lopes et al, 2004b andBettega et al, 2006), and C 4 H 10 (Floeder et al, 1985;Lopes et al, 2004b;and Bettega et al, 2007), as well as five-membered heterocyclic, aromatic compounds (Kossoski and Bettega, 2013). On the other hand, very little is known about the interaction of positrons with isomers, with just a few investigations for hydrocarbons (Floeder et al, 1985;Kimura et al, 2000;Makochekanwa et al, 2003;2008;Sueoka et al, 2005;and Nunes et al, 2015) and chiral enantiomers being available.…”