The adsorption of ammonia on polycrystalline thorium

摘要

The chemistry of the actinides has long been an area of great interest to many researchers, due to the unusual nature of the f-orbital electrons. Electron spectroscopies provide a useful means to study the electronic structure of the 5 f states, and how they affect the interactions of the actinide elements with various molecules. In this Study the interaction of ammonia with a polycrystalline thorium surface at two different temperatures has been investigated using X-ray and ultraviolet photoelectron spectroscopic techniques. Exposure to ammonia at ambient temperature results in the formation of both nitride (Th-N) and NHx species, characterised by N is photoemission peaks at 396.5 and 398.8 eV binding energy respectively, on the thorium surface. Exposure to ammonia at 100 K gives rise to an additional signal at 401.2 eV corresponding to physisorbed ammonia. Additional UPS results provided corroborating evidence for the effect of the surface temperature on the reaction with ammonia.