Probing adsorption on a nanoscale: field desorption microspectroscopy

Combining an energy analyzer with a field ion microscope equipped with a probe-hole which corresponds to just few atomic surface sites, spatially resolved energy analysis of ions field desorbed from the adsorbent surface is possible on a nm-scale. The experimentally measured values of the kinetic energy of field ions can be related (by means of a thermionic cycle) to the physically meaningful binding energy of corresponding adsorbed species. The development of the technique into a full serviceable microspectroscopy on a nanoscale allowed recent detection of the weakly adsorbed CO species on Pt(111) which are largely analogous to those adsorbed at high pressures and provided first results for the binding energy of Li adatoms in a coadsorption system, namely Li-O-W(112) for various lithium and oxygen coverages. In the present contribution, an overview of the experimental possibilities of the technique is given and recent results are discussed.