Electron scattering from allene and 1,2-butadiene

Abstract

The Schwinger multichannel method is employed to calculate elastic cross sections for electron collisions with allene (C3H4) and 1,2-butadiene (C4H6) molecules. Integral elastic and differential cross sections were obtained for both molecules in the static-exchange and static-exchange-polarization approximations, for energies from 0.1 eV to 10 eV. Both molecules have a π* shape resonance centered at 2.4 eV in the integral cross section, and a Ramsauer-Townsend minimum was found at around 0.34 eV in the allene cross section. The present differential elastic cross sections are compared between the two molecules and with the experimental and theoretical data available. Some of the features in the cross sections are analyzed and discussed in the context of the methylation effect, since the 1,2-butadiene molecule can be viewed as the methylated allene molecule. Electronic structure calculations are also performed in order to help in the interpretations of our results.