Adsorbate-induced surface rearrangement of the system Pd/Mo(1 1 1)

The thickness effect of Pd-adlayer on thermal stability of the Mo(1 1 1) surface has been investigated. It is found for θ>3 ML that heating to T>700 K results in faceting of the type {2 1 1}. At 920 K a reversible transition from the faceted to the planar surface occurs, which is accompanied by meaningful changes in work function opposite in sign to those measured upon the irreversible surface evolution during heating a new layer. It is also found that the faceting process is accompanied by changes in characteristic electron energy loss spectra with the loss energy of the faceted surface higher by 0.7 eV than that of the planar one. The dependence of desorption energy has been determined and four adsorption states found with their related energies of 4.82, 4.47, 4.13 and 3.92 eV/atom, respectively, in the range 0<θ<3 ML.