SELF-DIFFUSION OF POTASSIUM ON ULTRA-THIN EPITAXIAL POTASSIUM LAYERS

The self-diffusion of potassium on potassium layers supported by a Ni( 001) substrate was studied using quasielastic helium atom scattering. From the broadening of the quasielastic peak in the energy transfer sp ectra as a function of surface temperature the activation energy for s urface diffusion was determined to be 63 +/- 15 meV. This value is of the same order as that found in. the diffusion study of Na on Cu(001) using the same technique. The way in which the energy broadening depen ds on the transfer of parallel momentum suggests a jump diffusion mech anism. (C) 1997 American Institute of Physics.