An analytic degradation spectrum for H2

Using a discrete-energy-bin energy-apportionment method in conjunction with a detailed atomic cross-section approach, we obtain the degradation spectrum of H2 for a range of nonrelativistic incident-electron energies extending from threshold energies up to 50 000 eV. We fit the results so obtained with an analytic function of the incident energy and the energy variable. This representation exceeds in accuracy that achievable with simple scaling. We show that the various excited-state populations obtained using our analytic representation of the degradation spectrum agree closely with the corresponding values obtained directly from the discrete-energy-bin approach. Thus, by specifying the relevant cross sections and parameters in our two-dimensional fit to the degradation spectrum, we can solve all the nonspatial aspects of the initial stages of the nonrelativistic degradation problem of H2