The influence of valence electron state on the 2p ionization of atomic sodium by electrons

In a plane-wave Born approximation the total cross sections of the 2p shell ionization by electrons are calculated for Na atoms in the ground and in a number of excited states 2p(6)nl (n = 3, 4, 5; l less than or equal to n - 1). The relaxed-orbital (RO) Hartree-Fock and sudden perturbation (SP) methods are applied within the plane-wave Born approximation. Very strong dependence of the calculated cross sections on the valence electron state has been found. Large difference between the cross sections of RO and SP approximations is noticed near the threshold of ionization which disappears with the increase of the impact electron energy. The relaxation probabilities of the Hartee-Fock calculation strongly deviate from the hydrogenic ones for the 2p(6)ns and 2p(6)np states and coincide with them for the 2p(6)nl (l greater than or equal to 3) states.