Measurements of the total electron scattering cross sections (TCSs) from benzene, in the impact energy range of 1-1000 eV, are presented here by combining two different experimental systems. The first utilizes a magnetically confined electron transmission beam for the lower energies (1-300 eV), while the second utilizes a linear transmission beam apparatus for the higher energies (100-1000 eV). These cross sections have also been calculated by means of two different theoretical methods, the Schwinger Multichannel with Pseudo Potential (SMCPP) procedure, employing two different approaches to account for the polarization of the target for impact energies between 0.1 and 15 eV, and the Independent Atom Model with the Screening Corrected Additivity Rule including Interference effect (IAM-SCAR+I) paradigm to cover the 10-10 000 eV impact energy range. The present results are compared with available theoretical and experimental data, with the level of accord being good in some cases and less satisfactory in others, and some predicted resonances have been identified. In particular, we found a π * shape resonance at 1.4 eV and another feature in the energy region 4.6-4.9 eV interpreted as a π * resonance (2 B 2g symmetry), which is a mixture of shape and a core excited resonance, as well as a Feshbach resonance at 5.87 eV associated with the 3s (a 1g) Rydberg state. A Born-type formula to extrapolate TCS values for energies above 10 000 eV is also given. This study provides a complete set of TCS data, with uncertainty limits within 10%, ready to be used for modeling electron transport applications.
In this work, we revisit the low-energy electron scattering by benzene. We employed the Schwinger multichannel method implemented with pseudopotentials to carry out systematic cross section calculations with different schemes of polarization for the resonant and the totally symmetric irreducible representations within the D symmetry group. We present integral and differential cross sections for incident electron energies up to 12 eV and discuss the shape resonances and the presence of a Ramsauer-Townsend minimum and a virtual state in the former. We also discuss the relation of these physical phenomena with the different schemes of the polarization effects employed in our calculations. Finally, the comparison of our calculated integral and differential cross sections with the available data from the literature suggests improvement in the agreement between theory and experiment.
We report on a combination of experimental and theoretical investigations into the elastic differential cross sections (DCS) and integral cross sections (ICS) for electron interactions with dichloromethane, CH 2 Cl 2 , in the incident electron energy over the 7.0-30 eV range. Elastic electron scattering cross section calculations have been performed within the framework of the Schwinger multichannel method implemented with pseudopotentials (SMCPP), and the independent atom model with screening corrected additivity rule including interference effects correction (IAM-SCAR+I). The present elastic DCSs have been found to agree reasonably well with the results of IAM-SCAR+I calculations above 20 eV, and also with the SMC calculations below 30 eV. Although some discrepancies were found for 7 eV, the agreement between the two theoretical methodologies is remarkable as the electron impact energy increases. Calculated elastic DCSs are also reported up to 1000 eV for scattering angles from 0º to 180º together with total cross section (TCS) within the IAM-SCAR+I framework.
Electron scattering cross sections for pyridine in the energy range 0–100 eV, which we previously measured or calculated, have been critically compiled and complemented here with new measurements of electron energy loss spectra and double differential ionization cross sections. Experimental techniques employed in this study include a linear transmission apparatus and a reaction microscope system. To fulfill the transport model requirements, theoretical data have been recalculated within our independent atom model with screening corrected additivity rule and interference effects (IAM-SCAR) method for energies above 10 eV. In addition, results from the R-matrix and Schwinger multichannel with pseudopotential methods, for energies below 15 eV and 20 eV, respectively, are presented here. The reliability of this complete data set has been evaluated by comparing the simulated energy distribution of electrons transmitted through pyridine, with that observed in an electron-gas transmission experiment under magnetic confinement conditions. In addition, our representation of the angular distribution of the inelastically scattered electrons is discussed on the basis of the present double differential cross section experimental results.
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