Positron scattering from the cyclic ethers oxirane, 1,4-dioxane, and tetrahydropyran

Abstract

In this paper we report original measurements of total cross sections (TCSs) for positron scattering from the cyclic ethers oxirane (C 2 H 4 O), 1,4-dioxane (C 4 H 8 O 2 ), and tetrahydropyran (C 5 H 10 O). The present experiments focus on the low energy range from ∼0.2 to 50 eV, with an energy resolution smaller than 300 meV. This study concludes our systematic investigation into TCSs for a class of organic compounds that can be thought of as sub-units or moieties to the nucleotides in living matter, and which as a consequence have become topical for scientists seeking to simulate particle tracks in matter. Note that as TCSs specify the mean free path between collisions in such simulations, they have enjoyed something of a recent renaissance in interest because of that application. For oxirane, we also report original Schwinger multichannel elastic integral cross section (ICS) calculations at the static and static plus polarisation levels, and with and without Born-closure that attempts to account for the permanent dipole moment of C 2 H 4 O. Those elastic ICSs are computed for the energy range 0.5-10 eV. To the best of our knowledge, there are no other experimental results or theoretical calculations against which we can compare the present positron TCSs. However, electron TCSs for oxirane (also known as ethylene oxide) and tetrahydropyran do currently exist in the literature and a comparison to them for each species will be presented.

Positron and electron collisions with nitrous oxide: Measured and calculated cross sections

“…We note here that this model might actually somewhat overestimate the thermal transpiration correction for large molecules, such as 1,4-dioxane [26], compared to similar approaches available in the literature [27,28]. However, as N 2 O is a relatively small target (its hard-sphere diameter is 3.9Å [29]), we estimate that this effect would be very small (<1%) in the pressure range and at the temperatures we worked at and in any case is well within our cited TCS errors.…”

Positron collisions with ethene

“…[10] and the single-particle basis described in Ref. [30], except for the p-type function on the hydrogens, whose exponent is 0.2 in the present calculations. The geometrical structure of C 2 H 4 is shown in Fig.…”

A dynamical (e,2e) investigation of the structurally related cyclic ethers tetrahydrofuran, tetrahydropyran, and 1,4-dioxane

“…1. Note that previous measurements of total cross sections for electron 16,17 and positron scattering 18 from series of structurally related cyclic ethers have been useful in establishing trends in their scattering phenomena. Further, they have revealed the potential for constructing functional forms for describing the total scattering cross section in both the electron and positron scattering cases.…”