Experimental and theoretical analysis for total electron scattering cross sections of benzene

Abstract

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.

A Complete Cross Section Data Set for Electron Scattering by Pyridine: Modelling Electron Transport in the Energy Range 0–100 eV

“…The energy loss spectra have been measured with a standard electron transmission apparatus, which has been detailed in a previous publication [7], and is briefly described later in Section 4.1.1. Basically, it consists of a linear electron beam, which is energy analyzed with a high resolution hemispherical spectrometer, after passing through a gas cell containing pyridine at a well-defined pressure.…”

“…[1,3]). However, here we also incorporate new electron energy loss distribution functions for the main inelastic processes (vibrational, electronic excitation and ionization), as measured with a standard electron transmission apparatus [7], and double differential ionization cross sections derived from a reaction microscope coincidence analysis [8][9][10]. The reliability of this cross section data set is then evaluated by comparing the simulated electron intensity transmitted through a well-defined molecular density of gaseous pyridine, under strong magnetic field confinement conditions, with that directly measured with an alternative electron transmission apparatus [11].…”

“…Averaged energy loss (0-100 eV) spectrum for 100 eV incident electron collisions with pyridine, as measured with our linear transmission apparatus[7].…”

Electron scattering cross sections from nitrobenzene in the energy range 0.4–1000 eV: the role of dipole interactions in measurements and calculations

“…However, as we showed in recent papers, 30,31 TCS are considered to be crucial reference data to validate electron scattering data sets for modelling purposes, in particular to model radiation damage at the molecular level. 32 For this reason, we have recently measured and calculated total electron scattering cross sections for biologically relevant molecules such as pyrimidine, 33 pyrazine, 34 thiophene, 35,36 sevoflurane, 37 para-benzoquinone, 38 pyridine, 39 and most recently benzene 40 which is considered as a benchmarking molecule for basic carbon ring structures. In this context, nitrobenzene becomes even more relevant since comparison with the case of benzene may help elucidate the role of the NO 2 group in electron scattering processes.…”

“…For the lower energies [0.4-250 eV] we utilized our new magnetically confined electron scattering apparatus, 42 whilst from impact energies from 90 to 1000 eV the linear transmission-beam system described in ref. 40 has been employed. In addition, our independent atom representation with the screening corrected additivity rule including interference effects (IAM-SCARI) [43][44][45] has been applied to calculate the differential and integral elastic scattering cross sections, as well as the momentum transfer and the integral summed excitation and ionisation cross sections, over the whole energy range considered here [0.4-1000 eV].…”