POLARIZATION AND ORIENTATION IN ELECTRON-IMPACT EXCITATION TO NE-ASTERISK(2P(5)3P) STATES

The electron impact excitation of ground-state neon atoms to several, generally not LS-coupled, Ne(2p(5)3p) states is studied by electron-p olarized photon coincidence experiments on the Net(2p(5)3p) --> Ne(2p (5)3s) decay radiation. For four transitions the Stokes' parameters P- 1 to P-4 are published at fixed incident electron energies of 50 and 8 0 eV and in the electron scattering range of 22 degrees-70 degrees. A theoretical discussion is presented to show how information about the collision process can be extracted from the experimental results. For excitation to the three excited states with total angular momentum J = 2 the behaviour of the total angular momentum transferL(perpendicular to) as a function of the electron-scattering angle at 50 eV strongly suggests a common excitation mechanism.