XE ADSORPTION ON THE CU3PT(111) SURFACE

The interaction of Xe with the ordered and a disordered Cu3Pt(111) surface in the temperature range 50-120 K was investigated with AES, LEED, TDS, UPS and work function (WF) measurements. In the Xe coverage range of 0.1-0.6 ML on both surfaces the shape and the binding energy (BE) of the Xe5p1/2 and 5p3/2 UPS peaks are practically independent of the Xe coverage. The splitting of the 5p3/2 peak in the UPS spectra indicates that Xe condensation takes place at low coverages. This is confirmed by LEED; already at theta almost-equal-to 0.2 ML a square-root 3 x square-root 3 R30-degrees Xe superstructure is observed on both surfaces. In particular, only one 5p1/2 signal is observed on either surface and its BE is related to the respective macroscopic WF. At higher coverages both 5p signals broaden slightly to the higher BE side. This suggests that a two-dimensional (2D) phase transition (2D Xe(commensurate)-2D Xe(incommensurate)) occurs on both surfaces independent of their different surface composition. The results support the notion that the Xe-substrate interaction potential on both alloy surfaces is rather homogeneous in character.