Vibrationally state-selected reactions of ammonia ions. II. NH+3(v)+CH4

Abstract

The effects of vibrational excitation of the ammonia ν₂ inversion mode on the reaction of NH⁺₃(X̃,v=0 to 9) with methane have been measured in a tandem quadrupole mass spectrometer over the center‐of‐mass collision energy range 1.5 to 10 eV. The hydrogen abstraction channel is enhanced by nearly a factor of 2 at nine quanta of vibrational energy relative to the v=0 level of the ion. Added vibration in the ammonia ion umbrella‐bending mode facilitates the transition to the NH⁺₄ product ion geometry. Protonated methylamine is formed at lower kinetic energies by attack of the ion at the methane carbon center, but with increasing vibrational excitation of the ammonia ion, the protonated methylamine decomposes by 1,2‐elimination of molecular hydrogen and by C–N bond scission.