Time-resolved kinetic energy releases in propane

In this work we present a combined experimental and theoretical study of the time-resolved average kinetic energy release (KER) ε̄ of the H loss reaction in propane leading to the sec-propyl cation, C3H8+→sec-C3H7++H. The addition of a third field-free region to our double-focusing sector mass spectrometer, combined with previous results obtained by us and others, provides ε̄ values for ion lifetimes ranging from τmp<0.75 to 20.4μs. Their time dependence is nicely reproduced by Finite Heat Bath Theory. Furthermore, an analysis of the dependence of ε̄ on the excess non-fixed energy E# above the critical energy shows that the fraction ε̄/E# approaches a value of 1.0 for the metastable reaction.