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 ${\mathit{np}}^5$ (n+1)p[5/2${]}_3$ states in Ne (n=2), Ar (n=3), Kr (n=4), Xe (n=5), and the ${\mathit{np}}^5$ (n+1)p[5/2${]}_2$ state in Kr. The near-threshold linear-polarization fractions ${\mathrm{\eta }}_1$ were consistent with zero for all of the J=3 states measured, providing no evidence of Mott scattering. For J=2 excitation, ${\mathrm{\eta }}_1$ shows the clear influence of the intermediately coupled nature of the state. At threshold, the measured circular polarization ${\mathrm{\eta }}_2$ and linear polarization ${\mathrm{\eta }}_3$ for the J=3 states agree well with the LS-coupled threshold predictions. These results provide the basis for optical measurements of electron polarization.