Low-Energy Electron Scattering Research Articles

Low-Energy Electron Scattering from Ethyl Amine and Propyl Amine: A Comparative Study.

In this study, we investigate the low-energy electron (<20 eV) scattering cross sections for the linear ethyl amine and propyl amine using the R-matrix approach. A theoretical study is conducted, covering various cross sections such as elastic, symmetry-wise elastic, differential, momentum transfer, and electronic excitation. We obtained the ionization cross section using the CSP-ic and BEB methodologies. We unveil the intricate electron-amine interactions within these molecular systems. Additionally, our work extends to a comparative analysis among ethyl amine, propyl amine, and previously studied methyl amine systems. By comparing the obtained results, we discern subtle differences and similarities in the electron scattering behaviors across these structurally related amines. The findings presented herein shed light on fundamental electron-amine interactions, offering valuable insights for diverse fields ranging from chemical kinetics to astrophysics.

Low-Energy Electron Scattering from Pyrrole and Its Isomers.

Low-energy electron scattering from pyrrole and its isomers, such as 2-H pyrrole, cyclopropanecarbonitrile, and Z-2 butenenitrile, is explored in detail in this article. The electron interaction with the target molecules was studied through R-matrix theory. We have used minimal STO-3G and advanced DZP basis sets on a fine energy grid from 0.1 to 12 eV electron energy in the calculation. The properties of the STO-3G and DZP-based targets, such as their ionization energy, polarizability, dipole moment, rotational constant, principal moment of inertia, ground-state energy, and orbital energies, were investigated and compared to previously reported data. The elastic and inelastic channels showed the appearance of shape and Feshbach resonances for pyrrole and its isomers. The ultralow-energy region resonance was observed for Z-2 butenenitrile at 0.47 eV. With STO-3G and DZP basis sets, we estimated elastic, excitation, and momentum-transfer cross sections. The differential cross section for the present polar molecules was studied at 5 eV. The dissociative electron attachment channel for pyrrole and its isomers was studied for the pyrrolide anion. The data presented here will be helpful in astrophysical, astrochemical, atmospheric, and low-energy plasma modeling due to the presence of pyrrole and its isomers and the pyrrolide anion in the celestial bodies. The estimated data are also helpful in the biomedical field, radiation therapy, and pharmaceuticals.

Low-Energy Electron and Positron Scattering by para-Difluorobenzene.

The Schwinger multichannel method is employed in calculations of the elastic integral and differential cross sections for collisions of low-energy electrons and positrons with para-difluorobenzene (1,4-C6H4F2). The present calculations involving electron scattering have been performed using both static-exchange and static-exchange plus polarization levels of approximation. Our results indicate the presence of three resonances of π*-character in the low-energy region and a fourth resonance, of σ*-character, at higher energy levels. With respect to the positron scattering, the calculations were conducted using the static plus polarization approximation at three different polarization levels. The present calculated electron and positron cross sections show a reasonable agreement with the total cross sections measured by Makochekanwa et al. (J. Phys. B, 2004, 37, 1841). It is also important to highlight that our computed integral cross section for electron scattering indicates the presence of a Ramsauer-Townsend minimum, while the integral cross section for positron scattering indicates the presence of a virtual state.

Low-Energy Electron Scattering from c-C4F8

Electron collision cross-sections of c-C4F8 were investigated at low energies by using the R-matrix method. The static exchange (SE), static exchange with polarization (SEP), and close-coupling (CC) models of the R-matrix method were used for the calculation of the scattering cross-section. The shape resonance was detected with all the models at around 3~4 eV, and a Feshbach resonance was detected with the SEP model at 7.73 eV, in good agreement with the previous theoretical calculation. The resonance detected was also associated with the experimental dissociative electron attachment of c-C4F8, which displayed the resonances at the same energy range. The cross-sections calculated are important for plasma modeling and applications.

Low-Energy Elastic Electron Scattering from Helium Atoms

We reinvestigate a key process in electron-atom collision physics, the elastic scattering of electrons from helium atoms. Specifically, results from a special-purpose relativistic polarized-orbital method, which is designed to treat elastic scattering only, are compared with those from a very extensive, fully ab initio, general-purpose B-spline R-matrix (close-coupling) code.

Low-Energy Electron Scattering from Dimethyl Ether.

Low-energy (0.1 to 15 eV) R-matrix calculation is performed for dimethyl ether molecule. Electronic excitation and momentum transfer cross section for low energies are reported for the first time. Present differential cross sections show good agreement with previous data in terms of shape but are significantly higher in magnitude. Apart from low energies, we have also performed high-energy calculation (11-5000 eV) using spherical complex optical potential formalism. To deal with the molecular nature of the present target, we have applied an effective potential method in our computation for the first time. Good consistency can be seen at the overlapping energies of the two calculations.

Measurement of Proton Charge Radius by Low-Energy Electron Scattering

Measurement of Proton Charge Radius by Low-Energy Electron Scattering

Scattering of low-energy electrons and positrons by atomic beryllium: Ramsauer–Townsend effect

Total cross sections for the scattering of low-energy electrons and positrons by atomic beryllium in the energy range below the first inelastic thresholds are calculated. A Ramsauer–Townsend minimum is seen in the electron scattering cross sections, while no such effect is found in the case of positron scattering. A minimum total cross section of 0.016 a02 at 0.0029 eV is observed for the electron case. In the limit of zero energy, the cross sections yield a scattering length of −0.61 a0 for electron and a0 for positron scattering.

Scattering of low energy electrons with SiCl2 molecule by R matrix methodology

In the present paper we have reported low energy electron scattering calculations on SiCl2 molecule by Quantemol code for R matrix methodology.

Low Energy Electron Scattering from Fuels

In order to understand and optimize processes occurring during the ignition of plasma and its consequences in post-discharge for an internal combustion engine, especially considering the spark plug, we have produced in this work some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules in the energy range from 60 to 500 eV are reported, using the linear transmission method based on the Beer-Lambert law to first approximation. Aditionally to that, measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering were also discussed, for impact energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°–130°. The measurements were obtained using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons.

Low Energy Electron Scattering from Fuels

Total cross sections for electron impact and resonant structure for ethanol and methanol are reported.

Low energy electron collisions with the N2H radical

Low energy electron-scattering from the N2H molecule are carried using the R-matrix approach.

Spin-related Effects in Scattering of Spin-Polarized Low-energy Electrons from Magnetic and Nonmagnetic Surfaces

Spin-dependent scattering of polarized electrons from magnetic and non-magnetic surfaces was studied experimentally using single- and two-electron spectroscopies. Intensity asymmetry was observed in elastic and inelastic channels of scattering. Exchange and spin-orbit contributions to observed asymmetries are discussed.

Low-energy Electron Scattering with CH3C: Comparison with the High-energy Counterpart

Low-energy Electron Scattering with CH3C: Comparison with the High-energy Counterpart

Low-energy Electron Scattering from Argon

Low-energy Electron Scattering from Argon

Scattering of low-energy electrons by positive ions in a magnetic field. II. Resonances, transition probabilities, and transport frequencies

We analyze quantum-mechanically electron-ion collisions in a magnetic field at a low temperature, for which the electron's thermal energy is less than the energy gap between two Landau levels and the electron's Larmor radius is less than the characteristic impact parameter of close collisions without the magnetic field. To calculate transition probabilities, we use the analytical procedure proposed in the first part of our paper. We calculate the energy and lifetime of the resonant (autoionization) states of an electron embedded in the Coulomb electric field of an ion and in a uniform magnetic field. The obtained values coincide in order of magnitude with the known exact numerical values. We find that the electron backward scattering probability irregularly (chaotically) depends on the particle energy and the magnetic field. We propose analytical approximations for the collision transport frequencies, one of which describes the electron braking along the magnetic field and another, equalizing of the temperatures corresponding to the electron motion along and across the magnetic field.

Scattering of Low-Energy Electrons by Positive Ions in a Magnetic Field. I. Quantum Calculation of Transition Probabilities

We analyze electron–ion collisions in a magnetic field at a low temperature, for which the electron’s Larmor radius is less than the characteristic impact parameter of close collisions without the magnetic field. This ratio of spatial scales is realized in the photospheres of magnetic white dwarfs and in the experiments of antihydrogen creation. Under considered conditions, an electron transits from the initial to the final state via an intermediate quasibound state. We put forward an approximate analytical procedure for the quantum-mechanical calculation of the probabilities for an electron to transit between Landau levels due to a collision with an ion. We reduce the calculation to the inversion of finite-dimension matrices.

Scattering of low-energy electrons by isomers of C4H10

We report elastic integral, differential and momentum transfer cross sections for low-energy electron collisions with the two isomers of C4H10, butane and isobutane. We employ the Schwinger multichannel method with pseudopotentials at the static-exchange-polarization approximation, and cover energies from 1 eV to 20 eV. We investigate the influence of polarization on the isomer effect comparing the cross sections of these isomers and concluded that polarization has a small influence in that effect. We also compare our computed elastic cross sections with available total cross sections. Total ionization cross sections by electron impact are computed using the binary-encounter-Bethe (BEB) model and the results compared with available experimental data. The ionization cross sections for butane and isobutane are similar, showing that they also have a small isomer effect in the ionization process.

Depth and Angular Profiles of Inelastic Low-Energy Electron Scattering in Condensed Molecular Samples

Angular distributions of electrons scattered elastically and inelastically from cold solid molecular films of ethylene and nitrogen in various proportions, grown from the gas phase at different temperatures, have been studied by high-resolution electron energy loss spectroscopy. The probing depth of dipole and impact scattering has been investigated by covering the sample by overlayers of argon of increasing thickness. The angular distribution measured for elastically and inelastically dipole-scattered electrons was found to be peaked about the specular direction for all surface conditions studied, while a diffuse angular distribution was possible for electrons that underwent dipole-forbidden scattering. These results allow us to identify favorable conditions for monitoring the composition of a solid sample during the course of reactions occurring under exposure to low-energy electrons.

Specific Features of Low-Energy Electron Scattering by Thin Films of Cubic Crystals

The specific features of the electron states in thin films of cubic crystals are considered in the energy range above the vacuum zero of the crystal potential. It is demonstrated that bands of bound states embedded in the energy continuum can exist along particular directions of the two-dimensional Brillouin zone. These bands can substantially affect the intensity of low-energy electron scattering.