Role of exchange and kinematic in the generation of low-energy polarized electron pairs

Spin-polarized electron pairs are generated following the ionization of the valence electron of polarized Li atoms by polarized low-energy electron im pact. It is shown that the shapes of energy-sharing spectra of the pairs ar e influenced by an interplay of structures resulting from binary-encounter and exchange effects of the two electrons. The spin asymmetry is measured a t an excess energy as low as 20 eV and compared with dynamical calculations of different models. The shape of the asymmetry is explained on the ground s of symmetry and dynamics. [S1050-2947(99)50106-6].