title: Spin anisotropy for excitation in collisions between two one-electron atoms
abstract: The singlet and triplet contributions of excitation cross sections are studied theoretically for collisions between various two one-electron atoms. The spin anisotropy is shown to have a general behavior in the important impact energy range. At low energies triplet cross sections dominate completely over the singlet ones while the opposite is true when the active electron and projectile velocities are comparable. Beyond the matching velocity regime singlet and triplet contributions become identical. We propose a general dynamical interpretation based on the analysis of the time dependency of the electron probability density and probability current density.
authors.affiliation: Institute of Physics, University of Bergen, Allegaten 55, N-5007 Bergen, Norway.
authors.initials: JB
authors.lastname: Wang
authors.initials: JP
authors.lastname: Hansen
authors.initials: A
authors.lastname: Dubois