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Circularly polariztd light from BESSY with energies from 15 eV to 20 eV in normal incidence is used to excite oriented 4p,,,-hole states in thick layers of Rb on Pt(ll1). The CVV-Auger decay of these hole states is studied in a normal-cmission set-up. The preferential spin direction of the Augerelectrons has been measured to be parallel to the spin of the exciting photons near the excitation threshold and changes to be antiparallel at somewhat higher photon energies. This behaviour is consistent with an excitation varying with the photon energy and an atom-like model for the decay of the primary hole state. Thereby the two valence electrons participating in the decay are assumed to be dike and to be coupled to a singlet state.As the Augerdecay of the excited hole-state does not depend on the excitation, spin dependent Auger-spectroscopy opens a new method of studying excitations and unoccupied electronic states.

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Abstract. CVV Auger electrons emitted from K, Rb and Cs layers are studied using spinresolved spectroscopy. Oriented 3p, 4p and 5p hole states are excited by circularly polarized radiation in normal incidence. The photon energies range from 12 to 24 eV. With all h e materials, the degree and sign of the Auger electron spin polarization vary with the photon energy. As an atomic model of the Auger process predicls. and as a comparison of measurement8 with the calculated densities of states shows, the spin polaimtion is essentially determined by the symmetry of the final states reached in the primary (photo)excitation, Just above the excitation threshold, lhe preferential spin direction of the Auger electrons is measured to be panllcl to the spin of the exciting photons corresponding to a predominantly s-lkc symmetsy of the unoccupied final stares reached by the excitation. At higher photon energies the preferential spin direction changes to be antiparallel to the photon spin, corresponding to the mainly d-like symmetry of unoccupied States reached by the excitation.