• Comparison of experimental and theoretical electron-impact-ionization triple-differential cross sections for ethane

      Ali, Esam; Nixon, Kate; Murray, Andrew; Ning, Chuangang; Colgan, James; Madison, Don (American Physical Society, 2015-10-30)
      We have recently examined electron-impact ionization of molecules that have one large atom at the center, surrounded by H nuclei ( H 2 O , N H 3 , C H 4 ). All of these molecules have ten electrons; however, they vary in their molecular symmetry. We found that the triple-differential cross sections (TDCSs) for the highest occupied molecular orbitals (HOMOs) were similar, as was the character of the HOMO orbitals which had a p -type “peanut” shape. In this work, we examine ethane ( C 2 H 6 ) which is a molecule that has two large atoms surrounded by H nuclei, so that its HOMO has a double-peanut shape. The experiment was performed using a coplanar symmetric geometry (equal final-state energies and angles). We find the TDCS for ethane is similar to the single-center molecules at higher energies, and is similar to a diatomic molecule at lower energies.
    • Theoretical and experimental (e,2e) study of electronimpact ionization of laser-aligned Mg atoms

      Amami, Sadek; Murray, Andrew; Stauffer, Al; Nixon, Kate; Armstrong, Gregory; Colgan, James; Madison, Don (2014-12-08)
      We have performed calculations of the fully differential cross sections for electron-impact ionization of magnesium atoms. Three theoretical approximations, the time-dependent close coupling, the three-body distorted wave, and the distorted wave Born approximation, are compared with experiment in this article. Results will be shown for ionization of the 3 s ground state of Mg for both asymmetric and symmetric coplanar geometries. Results will also be shown for ionization of the 3p state which has been excited by a linearly polarized laser which produces a charge cloud aligned perpendicular to the laser beam direction and parallel to the linear polarization. Theoretical and experimental results will be compared for several different alignment angles, both in the scattering plane as well as in the plane perpendicular to the incident beam direction.
    • Triply differential (e,2e) studies of phenol

      da Silva, G. B.; Neves, R. F. C.; Chiari, L.; Jones, D. B.; Ali, E.; Madison, D. H.; Ning, C. G.; Nixon, K. L.; Lopes, M. C. A.; Brunger, M. J.; et al. (American Institute of Physics, 2014-09-28)