Unelastische Streuung niederenergetischer Elektronen an Methan, Propan und n-Heptan

Abstract

The inelastic scattering of 70 eV electrons (0.3 eV half width) by methane, propane, and nheptane has been measured in the angular range of 0 to 145°. From these data the relative total cross sections versus energy loss of the electrons for propane and n-heptane are calculated The energy distributions of the scattered electrons and the electrons ejected during the ionization processes are largely separated. In the case of n-heptane the ratio of the total number of processes leading to neutral excited states and the total number of processes leading to ionized states is determined. About 25% of the neutral excitations have energies below the first ionization potential, 75% above. Electronic levels of the ionized species are observed; some of them have been predicted by MO calculations. The amount of vibrational energy transferred to one electronic state is discussed, and the rapid change of the form of the energy transfer function with temperature (from 50 to 850°C) is experimentally demonstrated.