Investigation of spin-orbit effects in the excitation of noble gases by spin-polarized electrons

We have measured the integrated Stokes parameters of the light emitted following the impact excitation by polarized electrons of the np⁵ (n+1)p[5/2]₃ states in Ne (n=2), Ar (n=3), Kr (n=4), Xe (n=5), and the np⁵ (n+1)p[5/2]₂ state in Kr. The near-threshold linear-polarization fractions η₁ were consistent with zero for all of the J=3 states measured, providing no evidence of Mott scattering. For J=2 excitation, η₁ shows the clear influence of the intermediately coupled nature of the state. At threshold, the measured circular polarization η₂ and linear polarization η₃ for the J=3 states agree well with the LS-coupled threshold predictions. These results provide the basis for optical measurements of electron polarization.