The scattering of 40 eV electrons from magnesium:: a polarization correlation study for the 31P state and differential cross sections for elastic scattering and excitation of the 31P and 33P states

Excitation of the 3(1)P state of magnesium by 40 eV electrons has been studied experimentally using the polarized photon-scattered electron correlation method over a wide range of scattering angles (10degrees-120degrees). Measured Stokes parameters are consistent with the small angle (<20degrees) data of Brunger et al (1989 J. Phys. B:At. Mol. Opt. Phys. 22 1431-32). The measured linear Stokes parameters, and the circular polarization calculated from these parameters, assuming coherent excitation, are generally well produced by recent theoretical models, convergent close coupling, R-matrix with pseudo states, relativistic distorted wave and first-order many-body theory. Despite extensive testing, directly measured circular polarization data yielded low values at most scattering angles beyond 20degrees. Differential cross sections for elastic scattering and excitation of the 3(1)P and 3(3)P states were also measured over the angular range 10degrees-140degrees and compared with theoretical predictions.