SPIN-DEPENDENT STUDIES OF THE DYNAMICS OF HE+ ION NEUTRALIZATION AT A AU(100) SURFACE

Spin labeling techniques, specifically the use of electron-spin-polarized He{sup +} ions coupled with energy-resolved measurements of the ejected electron polarization, are used to study the dynamics of He{sup +} neutralization at a Au(100) surface. A marked correlation in the spins of the electrons involved in the Auger neutralization process is observed that is particularly pronounced at the highest ejected electron energies. A theoretical model is presented that explains the general characteristics of the data by considering the perturbation in the surface electronic structure induced by the presence of the (polarized) He{sup +} ion. This model, which includes the effects of ion velocity parallel to the surface, shows that the induced density of states is spin dependent, the spin dependence being most pronounced in the vicinity of the Fermi energy. {copyright} {ital 1999} {ital The American Physical Society}