Energy dependence of ion-molecule reactions. I. Methane

Abstract

The ion-molecule reactions of gaseous methane were studied at source pressures of up to 70 μ using a mass spectrometer operated without the usual source magnets. The range of ion exit energies used (0.2-1.8 eV) was obtained by using different ion path lengths as well as different field strengths. The operation of the mass spectrometer was checked by measuring the rate for the proton transfer reaction of CH₄⁺. The energy dependence and the rate of the reactions inside the ion chamber of all the primary ions in CH₄ were determined by plotting the cross section against the term, (ion exit energy)^-1/2.