Weak molecular chemisorption of N2/Pt(111)

The ordering in a higher-order-commensurate monolayer solid of Pt(111)-(3 x 3)-4 N-2, which has coexisting physisorbed and weakly chemisorbed N-2 species, is analyzed with model calculations. Density functional theory calculations are also used to evaluate properties of chemisorbed N-2 in a (2 x 2) unit cell on Pt(111). The relation of these results to the orientational ordering of N-2 on other metal surfaces is discussed.