Abstract
I present a general treatment for evaluating the angular distribution of ejected electrons from doublet resonant states and their interference with direct ionization. The formulation is applied to sodium, and the results are found to agree very well with two sets of experimental data. It is also found that the direct ionization cross section for sodium is unusually low for secondaries of ∼25 eV, with a sharp peak at the angle predicted by the binary encounter approximation. The dependence of the incident and the secondary energies and other features of the process are discussed in detail.