EXCITATION OF HE 3(3)P AND NE 3P STATES BY POLARIZED ELECTRONS

Integrated Stokes parameters for the transitions in helium 3(3)P --> 2 (3)S (388.9 nm) and neon 2p(5)3p[5/2](3) --> 3s[2/3](2) (640.2 nm) and 2p(5)3p'[3/2](1) --> 3s'[1/2](0) (626.7 nm) have been measured over t he electron energy range from threshold to 300 eV after excitation by polarized electrons. The measured zero values of P-2 for both the He 3 88.9 and Ne 640.2 nm photons are consistent with the LS coupling of th e upper states for each transition. Similarly, the measured non-zero v alues of P-2 for the 626.7 nm photons provide clear evidence of the br eakdown of LS coupling for the Ne 2p(5)3p'[3/2](1) state due to the sp in-orbit interaction of the atomic electrons. Non-zero values of the S tokes P-3 parameter indicate strong electron exchange effects, particu larly near threshold. Negative ion resonances show considerable effect s on the polarizations of the subsequent radiations. The effect of dif ferent core configurations on the alignment of excited states is discu ssed.