Ion—Molecule Reactions of Methane

The ionic reactions of gaseous methane have been investigated in a tandem mass spectrometer. The reactions of each primary ion, CH4+, CH3+, CH2+, CH+, C+, have been observed at 0.3 eV and several secondary-ion reactions have also been studied. An investigation of the effects of translational energy on many of these reactions demonstrated the efficient conversion of translational energy into internal energy. Evidence for randomization of the intermediate [C2HxD7−x+] ion in the methyl-ion—methane reaction is presented. Isotope effects in hydrogen-transfer reactions have also been investigated as a function of kinetic energy. The results are interpreted in terms of a transition from a complex model of reaction to a stripping model at higher energies.