On the rotational angular momentum polarization in N+2–He. Classical trajectory and hard-ellipsoid model calculations

Abstract

Classical trajectory and hard-ellipsoid methods are used to investigate collision-induced rotational alignment effects in N+2–He. Classical total, mf-resolved, and tensor cross sections for collision-induced rotational transitions are presented. Comparison of classical trajectory and quantum closed-coupled results show that total rotational inelastic cross sections are in good agreement, while mf-resolved and tensor cross sections agree only semiquantitatively. Velocity-averaged alignment parameters for N+2 ions drifting in a helium buffer gas are computed using a hard-ellipsoid model and a semiempirical two-dimensional velocity distribution. The alignment parameters are found to be smaller than the experimental values but lie in the range of the parameters obtained from a former quantum closed-coupled analysis.