ENERGY-TRANSFER BETWEEN OPEN-SHELL SPECIES AND METAL-SURFACES

It is shown that the electronic friction between a metallic surface an d an open-shell atom or molecule moving perpendicularly to it can be s ubstantially enhanced under experimentally interesting conditions due to the involvement of the Kondo or correlated mixed-valent state. The region of large friction is shifted from the point where the adsorbate resonance crosses the Fermi level to the point where the position-dep endent Kondo temperature is of the order of the physical electron temp erature. In addition, there is strong temperature and velocity depende nce. along with the breakdown of the local friction approximation. Nev ertheless, the strong frictions persist for reasonable experimental ve locities. (C) 1998 Published by Elsevier Science B.V.