Superelastic scattering of spin-polarized electrons from sodium

Superelastic scattering of spin-polarized electrons from laser-excited sodium atoms has been measured at incident energies of 2.0, 17.9, and 52.3 eV over the angular range 10°–120°. Circularly polarized excitation of the sodium atoms was used to produce pure 3 ${}_{}{}^2{}_{}{}^{}P_{3/2}^{}{}_{}{}^{}$ (F=3, $M_F$=±3) states, which are deexcited by collisions with spin-polarized electrons. The spin polarization of both the target electron and the incident electron allows the resolution of triplet and singlet contributions to $L_{\perp }$, the angular momentum transferred in the collision perpendicular to the scattering plane, and the measurement of r, the ratio of triplet to singlet cross sections. At low energy, agreement with theory is good over the entire angular range for r, but only at small angles for $L_{\perp }$. At high energy, agreement is excellent over the full angular range.