ORIENTATION OF NA-ASTERISK ATOMS FORMED UNDER GRAZING SCATTERING AT AN AL SURFACE

A study of the angular momentum orientation of excited Na 3p atoms by grazing scattering of Na+ ions from an Al surface is presented. The c oupled angular mode (CAM) method; previously used for the nonperturbat ive treatment of dynamic resonant electron-transfer in grazing atom-su rface collisions [1,2], is used for the study of this polarization pro blem. Following the dynamical approach of Brako [3,4] density matrix e lements are calculated within the 3p subspace of Na. A pronounced orie ntation of the orbital angular momentum perpendicular to the scatterin g plane is obtained. For the first time, a theoretical calculation has yielded a decrease of this atomic orientation with decreasing ion-bea m velocities below-0.4 Bohr. Overall agreement of the theoretical resu lts with experimental observations is found.