Stokes parameters from neon 3p(J=2) states excited by polarized electrons

For neon 3p states excited by transversely polarized electrons, the integrated Stokes parameters, P-1, P-2 and P-3, have been measured from threshold to 300 eV for the decay photons of 692.9, 667.8 and 717.4 nm wavelengths from the 2p(5)3p[3/2](2), 2p(5)3p'[3/2](2) and 2p(5)3p[5/2](2) tates, respectively. The P-1 and P-3 parameters for the 692.9 and 667.8 nm transitions indicate similar excitation mechanisms consistent with their similar LS component stares'. The non-zero P-2 indicates the breakdown of LS-coupling and the large P-3 values near threshold suggest a significant exchange process. For the 717.4 nm transition, the three Stokes parameters are much smaller than those of the other two lines. The low P-3 is surprising since the large (75.4%) D-3(2) LS-coupled component state was expected to cause large exchange effects.