ENERGIES AND ANGULAR CHARACTERISTICS OF THE RESONANCE IMPORTANT FOR PENNING AND ASSOCIATIVE IONIZATION IN HE(2(3)S)-H COLLISIONS

We report R-matrix calculations for energies and width of the lowest (2) Sigma resonance important for Penning and associative ionization in He-H collisions. The first ab initio determination of the angular distribution of the He (2(3)S)-H (1(2)S) resonance is reported. This resonance is shown to be anisotropic with considerable d character at small internuclear separation, whereas previously it had been assumed to have an isotropic distribution.