Effect of Chlorination on the Shape Resonance Spectrum of CHBr and CClBr Molecules in Collisions with Electrons.

In this work, we present a theoretical study of elastic electron scattering by the CHBr and CClBr molecules using the Schwinger multichannel method. Through the scattering amplitudes computed at the static-exchange and static-exchange plus polarization levels of approximation, we have obtained integral, momentum transfer, and differential cross sections for energies ranging from 0 to 20 eV. For both systems, the resonance spectrum was identified in the cross sections and characterized with basis on the analysis of the eigenvalues and eigenvectors obtained by diagonalization of the scattering Hamiltonian. Despite some discrepancies, our cross sections and resonance assignments are in overall good agreement with the experimental and theoretical data available in the literature. Present results also indicate that the effect of chlorination (i.e., the substitution of the hydrogen atoms by chlorine atoms in going from CHBr to CClBr) on the scattering process causes the following outcomes: the change in the position of the resonances in the low-energy regime and the increase in the magnitude of the cross sections for higher energies.