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

We present here an experimental study of the growth of Re/W(110). Auger electron spectroscopy, core level photoelectron spectroscopy and LEED 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 then buried by additional Re-layers (theta almost-equal-to 3 ML). An empirical model is developed to simulate the growth mode. The main effect of annealing is to increase the number of Re-enriched layers. The establishment of a surface alloy over several atomic layers introduces the new idea of local equilibrium. Finally, the extension to non equilibrium situations of the usual thermodynamical Born-Haber cycle allowed us to derive from the KTBIM the time-evolution of the W4f core level spectra and shifts in good agreement with the experimental data.