Photoionization of Ethane, Propane, and n-Butane with Mass Analysis

Abstract

Relative photoionization cross-section curves have been determined for parent and fragment ions of ethane, propane, and n-butane over the photon-energy range from the ionization potential to 14.0 eV. The data have been treated to give experimental breakdown curves which are in good qualitative and fair quantitative agreement with the predictions of the statistical theory of mass spectra. The results are also compared with data obtained by charge exchange, electron impact, and photoelectron energy analysis by other workers. Heats of formation of some ions have been obtained more accurately and the ionization potential of the C2H5 radical is confirmed to be 8.4 eV. Ion-pair formation of H− is shown to occur at least for ethane and n-butane and very probably for propane.