EXPERIMENTAL-STUDY OF THE GROWTH AND DISSOLUTION OF RE W(110) BY CORELEVEL PHOTOEMISSION SPECTROSCOPY - FORMATION OF A SURFACE ALLOY/

We present here an experimental study of the growth of Re/W(110). Auge r electron spectroscopy, core level photoelectron spectroscopy and LEE D experiments at T = 500 K and as a function of Recoverage theta show first (theta < 0.5 ML) a surface reconstruction followed (theta almost -equal-to 1 ML) by formation of a two-layer surface alloy which is the n buried by additional Re-layers (theta almost-equal-to 3 ML). An empi rical model is developed to simulate the growth mode. The main effect of annealing is to increase the number of Re-enriched layers. The esta blishment of a surface alloy over several atomic layers introduces the new idea of local equilibrium. Finally, the extension to non equilibr ium situations of the usual thermodynamical Born-Haber cycle allowed u s to derive from the KTBIM the time-evolution of the W4f core level sp ectra and shifts in good agreement with the experimental data.