Kinetic-energy dependence of rate constants and branching ratios for reactions of NH2+ ions with CH3NH2: Mobilities of NH2+ in He

Abstract Drift velocities of NH 2 + ions in He have been measured in the E/N range 5–90 Td and mobilities deduced. Kinetic-energy dependences of the total rate constant and of the branching ratios for the reaction of NH 2 + ions with methylamine have been determined in the energy range 0.03–1.2 eV using the drift-tube mass spectrometer technique. The increase of the total rate constant with energy is a consequence of an increase of the m/z 30 ion channel. The proton-transfer reaction shows a decrease in rate while the charge-transfer reaction shows an increase in rate with increasing kinetic energy. The NH 4 + channel remains a minor channel with a rate constant that is energy-independent. All the ions formed in the primary steps undergo proton transfer to methylamine; CH 3 NH 3 + is the terminating ion.