OVERLAYER FORMATION AND INTERDIFFUSION OF RH ATOMS AT THE PT(100) SURFACE

The kinetics of Rh inter-diffusion into a Pt(100) surface was investig ated on abrupt interfaces of Rh/Pt(100) which were artificially create d by thermal evaporation of 0.8 and 1.5 monolayers of Rh on a (5 x 20) reconstructed Pt(100) substrate at 110 K. Deposition of a small amoun t of Rh on a clean and reconstructed Pt(100) surface destroys the reco nstruction and yields a (1 x 1) structure. The kinetics of Rh diffusio n from the overlayer into the bulk was monitored by Auger electron int ensities of the Rh and Pt signals as a function of time and annealing temperature. The activation energies of inter-diffusion are derived to be 1.63 +/- 0.4 and 1.68 +/- 0.2 eV for 0.8 and 1.5 monolayer coverag es, respectively.