Phase transitions in the chemisorbed layer W(110) p (2×1)–O as a function of coverage. I. Experimental

The thermal disordering of oxygen chemisorbed on W(110) has been investigated as a function of coverage below half-monolayer coverage by measuring the angular distribution of intensity in the LEED superlattice reflections as a function of temperature. The transition temperature is a function of coverage, being much lower at low coverage. A partial phase diagram is constructed for this overlayer, and the low- and high-coverage limits are interpreted, respectively, in terms of an island–dissolution and an order–disorder transition.