title: Experimental and theoretical cross sections for positron scattering from the pentane isomers.
abstract: Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present.
authors.affiliation: Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan.
authors.forename: L
authors.initials: L
authors.lastname: Chiari
authors.affiliation: Department of Physics, University of Trento, Via Sommarive 14, Povo, Trento 38123, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Zecca
authors.affiliation: Departamento de Física Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Blanco
authors.affiliation: Instituto de Física Fundamental, Consejo Superior de Investigationes Científicas (CSIC), Serrano 113-bis, 28006 Madrid, Spain.
authors.forename: G
authors.initials: G
authors.lastname: García
authors.affiliation: School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Brunger