Chemical Reaction Kinematics XVI: Crossed Beam Study of the Reaction CH₂⁺ + H₂ → CH₃⁺ + H

Abstract

Abstract The reactions equation image were investigated with respect to the energy and angular distributions of the product‐ions at collision energies between 0.54 and 13.3 eV (cm‐system). An intermediate complex CH 4 + (or CH 2 D 2 + ) is formed with a high cross section at low energies which decays into the reactants and products with a ratio of 1:2. The intensity distribution of the CH 3 + ion in the velocity vector diagram indicates that the transition state of the dissociating complex acts as a spherical top and decays isotropically in space. The CH 3 + ion is often formed with rotational excitation, CH 2 D + and CD 2 H + are formed with equal abundance at low energies. The relative abundance of CH 2 D + at first increases with energy and simultaneously preferred forward scattering of this ion is observed. This corresponds to the transition to a stripping process. Beyond 5.5 eV, the CH 2 D + abundance decreases because of the preferred formation of CHD + + H + D. The relative abundance of CD 2 H + rapidly decreases with increasing energy. The intensity distribution, however, remains isotropic around the center of mass. CHD + is preferentially scattered into the forward direction at high energies. Below about 1 eV, a small part of the reaction enthalpy is transformed into translational energy of the products. With increasing energy, the translational exoergicity becomes increasingly negative.