Charge-transfer and impact-ionization cross sections for fully and partially stripped positive ions colliding with atomic hydrogen

Classical trajectory calculations have been used to predict the charge-transfer and impact-ionization cross sections for collisions of A^+q+H in the velocity range of (2-7) × 10⁸ cm/sec. The calculations employ a three-dimensional Monte Carlo approach that uses a classical description of the H atom and the Coulomb forces among all particles to obtain the cross sections. The positive ions studied include fully stripped A^+q, with q=1-8, 10, 14, 18, 26, and 36, and partially stripped B^+q, C^+q, N^+q, and O^+q, with q≥3. The total electron-loss cross sections (sum of charge exchange and impact ionization) vary only slightly with velocity for the higher charge states and reach a value of 2 × 10^-14 cm² for Kr⁺³⁶ + H collisions. The importance of impact ionization relative to charge transfer is found to decrease with increasing q in the velocity range studied. Transition probabilities versus impact parameters are presented for the H⁺ + H and Ar⁺¹⁸ + H reactions. The calculations are in reasonable agreement with experimentally measured cross sections for the H⁺, C^+q, N^+q, and O^q++H systems.