Semiempirical Calculations on Low-Energy Electron Scattering by Zn and Cd Atoms

Abstract

Since total cross section measurements for electron scattering by Zn and Cd performed in the 1970s, the existence of p-wave shape resonances below 1 eV are well established in the literature. It was suggested that a second d-wave shape resonance could exist in both systems at an energy slightly higher than the one recorded for the p-wave but still below the inelastic threshold. We report elastic scattering calculations for electron collisions with Zn and Cd atoms below 4 eV using a semiempirical approach, as well the scattering length for both targets. Our results show that, indeed, the d-wave shape resonance is found in Zn but absent in Cd. In fact, our cross sections and the few other ones available for this energy range are in discrepancy with the available experimental total cross sections for Cd.

Low Energy Positron Scattering by F and F2

“…The same polarization models were chosen for the SD approach, nonetheless, there are significant differences in the static and correlation potentials, due to the SD parametrization. We have observed in a recent work that the SD parametrization does not represent the atomic electronic density correctly inside the atomic shell region, which may impact negatively in the determination of the static and correlation potentials, as also observed by Rabasović et al in electron-atom scattering studies. This effect has little consequence for high energy projectiles; however, it is expected to have considerable influence in the low energy region.…”

Cross Sections for Electron Scattering from Cadmium: Theory and Experiment

“…To obtain orbital kinetic energies, we have performed a quantum chemical calculation on a Cd atom in Gaussian 09. 74 Here, we used a B3LYP model chemistry 75 with a Sapporo-TZP-diffuse basis set, 76 19 as given (×) and multiplied by 0.1 (+) and for theoretical calculations: Present OP (----), present ROP (-⋅ -), present RCCC (--), Dirac (1991) 26 (---), OP (1991) 25 (---), real OP 24 (---), semiempirical 34 (---), and recommended (--).…”

“…Also shown are a relativistic calculation solving the Dirac equation (Dirac), 26 an OP approach (OP), 25 a real OP approach (real OP), 24 and a recent semiempirical approach. 34 Journal of Physical and Chemical Reference Data ARTICLE scitation.org/journal/jpr FIG. 4.…”

“…4. Total ICSs (10 −16 cm 2 ) for electron scattering from Cd as a function of electron impact energy for the measurements of Kontros et al 19 as given (×) and multiplied by 0.1 (+) and for theoretical calculations: Present OP (----), present ROP (-⋅ -), present RCCC (--), Dirac (1991) 26 (-----), semiempirical 34 (---), and our recommended total ICS (Recommended).…”

“…Kontros et al 19 used their HES to measure TCSs for electron scattering from Cd in the range 0-15.3 eV, thus giving the elastic ICS for impact energies below the inelastic threshold of 3.75 eV. Recent semiempirical calculations 34 agree reasonably well in energy dependence with these measurements below 0.7 eV, but the measurements are an order of magnitude higher in the range 2-3.75 eV. As the calibrated ionization values were used to calibrate the other measured cross sections, 19 it is possible that the ambiguous factor of 10 in the ionization figure was transferred to the TCSs.…”