Unimolecular gas-phase hydrogen randomization within 2-methyl-propane radical cations

Abstract

The low and high energy electorn impact (EI) mass spectra and the field ionization (FI) mass spectra of 2-methylpropane, 2-methyl[2-²H]propane, and 2-[²H₃]methyl[1,1,1,3,3,3-²H₆]propane have been measured. Metastable transitions following FI have been measured. There is no hydrogen–deuterium randomization within the molecular ions following FI. There is partial randomization prior to the formation of methyl ions following high energy EI, but not prior to the loss of methane. Hydrogen randomization within the 2-methylpropane ion is seen as having a high activation energy and a high frequency factor.