Low energy secondary electrons ejected by metastable helium (He) beam: Observation of He spin dependence

Intensity of low energy electrons ejected by a spin polarized metastable helium (He^∗) beam was measured for clean and water-adsorbed Fe surfaces. A definite He^∗ spin dependence was found in the intensity of electrons with energies just above the vacuum level of the sample when an Fe surface was covered with a water multilayer. The He^∗ spin dependence was found to be associated with the He^∗ deexcitation process. The spin dependence is likely to be due to the spin-dependent secondary processes.