Atomic collision parameters for electron de-excitation of the 4S-3P transition of sodium

A comparison of measured Stokes parameters and atomic collision parameters (P-lin gamma, L-perpendicular to, P+) is made for the excitation and de-exc itation of the 3S-3P and 4S-3P transitions of Na respectively, for electron s with incident energies of 22, 30 and 50 eV. These parameters are obtained from 'time-inverse' experiments in which electrons are either superelastic ally (3P-3S) or inelastically (3P-4S) scattered from the laser prepared 3P state, The data are compared with calculations from a convergent close coup ling (CCC) model and a second-order distorted wave Born (DWB2) model. Both models demonstrate very good agreement for 3S-3P transitions. For the 4S-3P transitions, the DWB2 is in better accord with experiment than the CCC for the P-lin, parameter, the CCC is in excellent agreement with experiment fo r gamma and LI, and neither is in accord with experiment for P+.