The diffusion of lithium on a Ru(001) surface has been studied with nuclear magnetic resonance techniques using the radioactive isotope ${}^8\mathrm{Li}$ as a probe. As a function of substrate temperature and alkali metal coverage the nuclear spin-lattice relaxation measurements show the existence of two distinctly different diffusion barriers on the surface, valued at 0.46 and 0.22 eV. The former is attributed to jumps from step to terrace sites, whereas the latter is the barrier between adjacent terrace sites. At 200 K the Li diffusion was observed from low to full coverage.

• Received 8 September 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.656