Secondary Ions in the Mass Spectrum of Propane

Abstract

The secondary spectra arising from ionic reactions in propane at several mean ion energies are reported. The results are compared with computed values taken from results obtained by the elegant techniques developed by Lindholm. From the comparison a calculation is made for the secondary spectrum obtained by bombarding C₃H₈ with C₂H₄⁺ ions. Experiments using mixtures of C₂D₄ and C₃H₈ lead to an observed secondary‐ion spectrum which is in good agreement with that calculated. A significant number of ionic fragments in the secondary spectrum appear to be formed by endothermic processes. It is assumed that translational energy supplies the required energy. Some appearance‐potential measurements support this assumption. There appears to be some evidence for CH₃^— transfer when C₃H₈ is bombarded either by C₂H₅⁺ or C₂H₄⁺. In both cases there is also a competing H^— transfer process.