IMAGING AND TUNNELING SPECTROSCOPY OF INDIVIDUAL IRON ADSORBATES AT ROOM-TEMPERATURE

We have imaged for the first time individual atoms and small clusters of metal species on a metal substrate at room temperature by means of a scanning tunneling microscope (STM) operated under ultrahigh vacuum conditions. The system we have studied is Fe on W(110), for which a ca rbon-induced (15x3)- reconstruction of the W(110) substrate has been f ound to prevent surface diffusion of Fe atoms at 300 K. Upon positioni ng the STM-tip above individual Fe adsorbates, local tunneling spectra could be obtained. A pronounced empty-state peak at 0.5 eV above the Fermi level has been found, characteristic for individual Fe adsorbate s. This peak can serve as a fingerprint for the identification of Fe a dsorbate species.