INTERACTIONS OF SRF2 AND PRF3 WITH TIC(111) AND SI(111) SURFACES STUDIED BY LOW-ENERGY D+ SCATTERING SPECTROSCOPY

On the basis of neutralization of scattered low-energy D+ ions, the na ture of the bonding of ionic molecules adsorbed on metal and semicondu ctor surfaces has been investigated. It is found that SrF2 reacts with the active dangling-bond states of the TiC(111) surface and the ionic bonding between Si2+ and F- ions is strongly weakened. However, the i onicity of the adsorbates recovers after oxygenation or hydrogenation of the TiC(111) surface since H or O passivates the dangling-bond stat es at the interface. On the other hand, the dangling bond of Si(111) h as relatively little effect on the ionic Sr-F bond formation and rathe r dissociation of SrF2 is promoted at an elevated temperature due to p referential reaction of F with Si. In terms of PrF3, ionicity is stron gly reduced on both Si(111) and TiC(111) surfaces and oxygenation of t he surface has very little effect, suggesting that PrF3 is dissociativ ely adsorbed and Pr forms covalent or metallic bonds with the substrat e. [SO163-1829(98)03739-4].