The magnetic properties of a chemisorbate on a ferromagnetic surface a
re investigated by means of spin polarized metastable deexcitation spe
ctroscopy (SPMDS). The study was carried out with oxygen on magnetized
Fe(110) films evaporated on W(110). By using a spin polarized He(2(3)
S) beam, an intensity change is observed in the iron related structure
near the Fermi edge when reversing the polarization of the incident H
e beam. This asymmetry changes its sign after oxygen exposure.