Spin polarisation of electrons scattered superelastically by laser-excited Na atoms

The authors have measured the spin polarisation of electrons scattered superelastically from laser-excited Na atoms at a collision energy of 20 eV and a scattering angle of 30 degrees . The measured spin polarisation is 0.095+or-0.048 for scattering from the 3p 2 P 1/2 excited state of Na. The polarisation changes sign if the laser is tuned to the 3p 2 P 3/2 state, as is expected on formal grounds. They also present calculations of the spin polarisation using theoretical scattering amplitudes from Moores (1971) and from Kennedy et al. (1977).