Atomically resolved images of the interaction of ammonia with chemisorbed molecular oxygen on a Pt(111) surface have been obtained with a scanning tunneling microscope (STM) operated at 5 K in ultrahigh vacuum. Adsorption of NH3 onto a structure formed by preadsorbed O2 molecules results in a structure indicative of an NH3-O2 complex. Annealing of the ammonia-oxygen overlayer to 400 K produces a well ordered p(2�2) N overlayer. For annealing temperatures slightly less that 400 K, the nitrogen is present in a mixed p(2�2) + (v3�v3)R 30� overlayer. Exposure of the N-covered surface to H2(g) reveals the formation of NH molecules, which can be distinguished from N atoms in several ways. Also apparent in the images are H atoms, which are highly mobile and easily moved by the STM tip. This work provides new insights into the formation and hydrogenation of nitrogen atoms on platinum surfaces.

Observations at the single-molecule level of the formation of nitrogen atoms on the Pt(111) surface from the reaction of ammonia with molecular oxygen

245th National Meeting (2013)

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