Dissociative Charge-Exchange Reactions of Rare-Gas Ions with Propane

Abstract

Dissociative charge-exchange reactions of rare-gas ions with propane and with partially deuterated propanes have been investigated using a modified commercial mass spectrometer. The experimental results for propane are in good agreement with data previously obtained using much more sophisticated instrumentation. Charge-exchange spectra obtained with 2,2-dideuteropropane and with 1,1,1,3,3,3-hexadeuteropropane permit the determination of details of the fragmentation mechanism. The data suggest that both s-propyl and n-propyl ions are formed by charge exchange, but that the latter is a relatively unimportant process. Ethylene is formed chiefly by 1,3 elimination of methane from the molecule ion, but 1,2 elimination becomes relatively more important with increasing recombination energy of the rare-gas ion. In contrast to observations on the vacuum uv photolysis of deuterated propanes, the present data indicate that elimination of molecular hydrogen as HD is of substantial importance in the over-all ionic decomposition of both compounds.