Dependence of Calculated and Experimental Propane Mass Spectra upon Electron Voltage

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Abstract
Experimental propane mass spectra have been obtained with bombarding electrons ranging in energy from 14 to 500 v. The quasi-equilibrium theory has been used in calculating the same spectra. The grossly simplified version of the statistical theory that satisfactorily predicts the 70-v mass spectrum is inadequate at low voltages, but if half the theoretical number of oscillators are assumed to be effective in the parent-ion and activation energies that bear no simple relation to experimental appearance potentials are employed, a semiquantitative fit of the experimental data is obtained. The description of the decomposition reaction of a molecule-ion in terms of a collection of harmonic oscillators is clearly unsatisfactory. However, the more general form of the quasi-equilibrium theory, in which it is assumed only that the reaction coordinate is separable, does appear to be applicable.