Elucidating Surface Structure with Action Spectroscopy

Surface Action Spectroscopy, a vibrational spectroscopy method developed in recent years at the Fritz Haber Institute is employed for structure determination of clean and H₂O-dosed (111) magnetite surfaces. Surface structural information is revealed by using the microscopic surface vibrations as a fingerprint of the surface structure. Such vibrations involve just the topmost atomic layers, and therefore the structural information is truly surface related. Our results strongly support the view that regular Fe₃O₄(111)/Pt(111) is terminated by the so-called Fe_tet1 termination, that the biphase termination of Fe₃O₄(111)/Pt(111) consists of FeO and Fe₃O₄(111) terminated areas, and we show that the method can differentiate between different water structures in H₂O-derived adsorbate layers on Fe₃O₄(111)/Pt(111). With this, we conclude that the method is a capable new member in the set of techniques providing crucial information to elucidate surface structures. The method does not rely on translational symmetry and can therefore also be applied to systems which are not well ordered. Even an application to rough surfaces is possible.