LEED STUDY OF NO ADSORPTION-INDUCED RESTRUCTURING OF A SINGLE-DOMAIN PT(001)-(20X5) SURFACE AT 80-410K

NO adsorption on a single-domain Pt(001)-(20 x 5) surface at 80-410 K has been studied with low-energy electron diffraction (LEED). The restructuring of the topmost Pt-(20 x 5) layer and the growth process of the adsorbed NO layer are found to depend on the surface temperature. At 330-390 K, a double-domain NO-c(2 x 4) layer grows while restructuring the Pt-(20 x 5) layer into the (1 x 1) structure. On the other hand, a single-domain NO-c(2 x 4) layer grows anisotropically at 230-270 K. At 80 K, the (20 x 5) --> (1 x 1) restructuring of the topmost Pt layer occurs suddenly in an NO exposure range of 0.8-1.0 L. A model for the single-domain Pt(001)-(20 x 5) surface formation is presented. The restructuring of the Pt(001)-(20 x 5) surface induced by NO adsorption is discussed.