Analysis of Observable Quantities from Excited Rubidium Impacted by Electrons at Low Incident Energy

The observable quantities (Stokes parameters, orientation parameter L⁺, alignment angle γ, linear-light-polarization degree P_lin) of rubidium, excited from S to P and scattered by electrons at 20eV, are calculated with the two distorted wave methods, i.e. the ordinary distorted wave method distorted wave method (ODWM) and the indirect-relativistic distorted wave method (IRDWM). Compared to the measured results of superelastic electron scattering from laser excited rubidium at incident energy 20eV, the result shows that the two kinds of theoretical calculations are partially in agreement with the experimental results. When scattering angle is smaller than 45°, the Stokes parameters and both the calculations of orientation parameter and alignment are consistent with the measured data. Within the scattering angles 70°-120°, the IRDWM results are in agreement with the measurements, which shows that indirect relativistic effects exist during the process of rubidium scattering by low-energy electrons.