Spin-polarized electron capture during ion impact on a ferromagnetic surface

25-keV He+ ions are scattered from a clean and Mn-covered (1 ML) Fe(100) su rface. The spin polarization of electrons captured into excited 3 P-3 state s of He atoms is probed via an analysis of polarized fluorescence light. Fo r projectiles impinging from grazing to normal incidence we observe the sam e spin polarization of captured electrons. By a coverage of 1 ML of Mn atom s we demonstrate the surface sensitivity of the method and discuss its pote ntial for spin-sensitive microscopy and sputter depth profiling. [S0163-182 9(99)00406-3].