Pa. Hayes et al., EXCITATION OF HE 3(3)P AND NE 3P STATES BY POLARIZED ELECTRONS, Journal of physics. B, Atomic molecular and optical physics, 29(17), 1996, pp. 3989-4000
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.