Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

Abstract

Absolute cross sections for electronic excitation of pyrimidine by electron impact J. Chem. Phys. 144, 024302 (2016) In this work, we report theoretical and experimental cross sections for elastic scattering of electrons by chlorobenzene (ClB). The theoretical integral and differential cross sections (DCSs) were obtained with the Schwinger multichannel method implemented with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR). The calculations with the SMCPP method were done in the static-exchange (SE) approximation, for energies above 12 eV, and in the static-exchange plus polarization approximation, for energies up to 12 eV. The calculations with the IAM-SCAR method covered energies up to 500 eV. The experimental differential cross sections were obtained in the high resolution electron energy loss spectrometer VG-SEELS 400, in Lisbon, for electron energies from 8.0 eV to 50 eV and angular range from 7 • to 110 • . From the present theoretical integral cross section (ICS) we discuss the low-energy shape-resonances present in chlorobenzene and compare our computed resonance spectra with available electron transmission spectroscopy data present in the literature. Since there is no other work in the literature reporting differential cross sections for this molecule, we compare our theoretical and experimental DCSs with experimental data available for the parent molecule benzene. Published by AIP Publishing. [http://dx

Experimental and theoretical electron-scattering cross-section data for dichloromethane

“…Such joint experimental and theoretical procedure has been implemented recently in our laboratory in the case of electron scattering from acetone [20] and chlorobenzene [21], and revealed to be very reliable when compared to other available data in the literature. Therefore we are confident that the procedure implemented here for dichloromethane differential cross sections can be relied upon across the energy range studied (7.0-30 eV).…”

Elastic electron scattering from chlorobenzene

“…Further cross sections calculations were made in the 20-500 eV range using the independent atom model (IAM). The results are compared with the experimental data and the SMCPP theoretical results of Barbosa et al [8]. The results are also compared to existing experimental DCSs for similar benzene related targets discussed above to relate the importance of the benzene group in the collision dynamics.…”

“…The RFT [21] was employed in both experiments to determine normalized elastic electron scattering DCSs for chlorobenzene. However, its application in the two experiments was different and needs to be elaborated; this is important since the CSUF experiment used an aperture collimator of gas whereas CSUF data; Barbosa et al [8]; theory: SMCPP SEP calculation [8]; MCOP SEP calculation.…”

“…This would be a more dilute form of processing, but nevertheless of industrial interest in industrial exhaust stacks, etc. A discussion of anion resonant-state symmetries associated with resonant DEA to C 6 H 5 Cl for attachment to the benzene ring and attachment to the C 6 H 5 -Cl bond is given by Barbosa et al [8]. For such applications, it is important to know the energy and scattering angle dependence of electron collisions with this target for modeling studies.…”

“…The first experimental electron scattering DCSs and a detailed theoretical study of elastic scattering resonances of chlorobenzene was made by Barbosa et al [8]. Their experimental work was undertaken at E 0 values of 8 eV and above, so they could not empirically detect resonant structures which lay below 8 eV, but from their theoretical studies using the Schwinger multichannel with pseudopotentials (SMCPP) method, they identified resonances characterized as π * at around 0.7, 0.76, and 5.2 eV belonging respectively to the B 1 , A 2 , and B 1 symmetries and a σ * resonance at 2.8 eV of A 1 symmetry, in agreement with most of the literature published.…”