Mass Spectrum of Propane: Isotope Effect and Metastable Ions

The mass spectra of propane and of propane-2,2-d2 have been calculated assuming that the mass spectra result from successive and competing unimolecular reactions following initial vertical ionization of the parent molecules. Reasonable agreement with experiment is found for the change in mass spectral pattern with deuterium substitution. The metastable ion peaks are shown to be a normal part of the mass spectrum.