Chemical Reaction Kinematics XVIII: Reactions of NH₃⁺, NH₂⁺ and NH⁺ with Hydrogen and of N⁺ with HD

Abstract

Abstract The angular energy distributions of the product‐ions of various reactions NH n + + H 2 → NH n+1 + + H were measured at collision energies from 0.4 to 10eV (c.m. system). The relative intensities and energy distributions of the ions NH n D + , NH n‐1 D 2 + and NH n‐1 D 2 + produced in the reactions with D 2 were also investigated. The essential features of the reaction potential surface of NH 3 + + H 2 were calculated by the unrestricted Hartree‐Fock method. NH 3 + reacts with D 2 in an impulsive manner at all collision energies used, picking up a D atom. Simultaneously, the NH 3 D + ion formed is unreactively or reactively scattered on the remaining D atom and NH 3 D + or NH 2 D + , respectively, is the production observed. At the lowest collision energy used, NH 2 D + is even more abundant than NH 3 D + . The cross section has a maximum at about 2eV (c.m. system). Although a deep potential well of more than 5 eV exists in the potential hypersurface of the reactions of NH 2 + and of NH + with H 2 , they become noticeably impulsive at a c.m. collision energy of 1 eV. The symmetric intensity distribution around the c.m. point observed at smaller energies indicates a strong interaction of the freed hydrogen atom with the incident ions. Complex formation in the reaction of NH 2 + which has a small cross section may contribute at low energies. Complexes are less important in the reaction of NH + which has a large cross section because of a high rotational energy barrier. The reaction of N + with HD was found to occur in an impulsive manner. At low energies, the velocity distribution indicates a strong interaction between the freed hydrogen atom and the incident ion. The intensity ratio NH + /ND + of the two products of the reaction with HD is smaller than unity below 4eV and increases at higher energies.