Electron scattering by trimethylene oxide, c-(CH2)3O, molecules

Abstract

Electron-scattering cross sections have been determined for trimethylene oxide, cyclic (CH(2))(3)O molecule, both experimentally and theoretically. The absolute total cross section (TCS) has been measured over energies from 1 to 400 eV using a linear electron-transmission method. The obtained TCS generally decreases with rising energy, except for the 3-10 eV range, where some resonantlike structures are discernible. Integral elastic cross section (ECS) and ionization cross section (ICS) have been also calculated up to 3 keV in the additivity rule approximation and the binary-encounter-Bethe approach, respectively. Their sum, ECS+ICS, is in a good agreement with the measured TCS. Comparison of the TCS energy dependence for trimethylene oxide with that for its isomeric open-chain counterpart--acetone, (CH(3))(2)CO, has also been made. Moreover, examination of experimental TCSs for the cyclic (CH(2))(n)O, n=2-4, ether series reveals that the intermediate-energy molecular TCSs for members of that family can be nicely represented as a sum of the effective TCSs for particular constituents of the molecule, i.e., methylene groups and oxygen atom. Finally, based on these partial TCSs, the TCS for the c-(CH(2))(5)O--the next member of the series--has been determined and compared with the respective ECS+ICS values computed here for this compound.

Scattering of electrons from acetaldehyde and acetone

“…Comparison of electron-scattering TCSs for these carbonyl compounds may show how replacing one hydrogen atom in (CH 3 )CHO by the methyl group, to form (CH 3 ) 2 CO, influences electron interaction with molecules (substitutional effect). In addition, to examine how the arrangement of atoms in the target molecule reflects in the TCS energy behaviour (isomer effect), the current TCS results for the open-chain (CH 3 )CHO and (CH 3 ) 2 CO molecules will be confronted with the recent TCS data (Szmytkowski et al 2008(Szmytkowski et al , 2009 for their isomeric ring counterparts c-(CH 2 ) 2 O and c-(CH 2 ) 3 O respectively.…”

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.…”

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

“…A comparison, where possible, with corresponding electron total cross sections, [16][17][18] suggested that between 200-300 eV incident impact energy the magnitudes of the positron and electron TCSs were converging towards a common value. This makes good physical sense as two of the major processes that set positron and electron scattering apart, namely, positronium formation and exchange are expected to be negligible by 100 eV.…”

“…For positron scattering from tetrahydropyran, we are able to compare to corresponding electron total cross section data from Szmytkowski and Ptasińska-Denga 16 and results from the independent atom model calculations of Szmytkowski et al 17 All these results, both positron and electron, are shown in Fig. 4 being listed in Table IV.…”

“…The results contained within this paper conclude our studies on the cyclic ethers. [16][17][18] will be made later in this paper. In addition, here we also seek to investigate if there are any trends in the energy dependence of the positron total cross sections for all the cyclic ethers we have investigated, and if so can those trends be related to some of the more important physico-chemical properties (see Table I) of the species in question.…”