Abstract
XPS and UPS Photoelectron Spectroscopy techniques (Anoble ESCA-5 Spectrometer which permit pressure from 1-10-11 Torr) have been used to investigate water vapour interaction with clean and pre-oxygen exposed chromium surface in the temperature range 80-623 K.
Initially at low exposure (a < monolayer), the interaction of water vapour with clean chromium surface is dissociative at active site of chromium atoms through the formation of an adsorbed oxyhydroxyl layer together with molecular water which is coordinately bonded to the unsaturated site, via the oxygen which strongly held. The second layer which represents the physically adsorbed layer occurs at higher than one monolayer coverage through water molecules hydrogen bonded to the chemisorbed oxyhydroxyl layer. Models and the mechanism of the dehydroxylation of this layer when the exposed surface warmed to room temperature, have been suggested by the monitoring of the XPS and UPS spectra.