The interaction of CO2 and H2O with Sr films studied with MIES and UPS (HeI)

Metastable impact electron spectroscopy and ultraviolet photoelectron spectroscopy (HeI) were applied to study the interaction of CO2 and H2O with Sr films. The films were prepared by evaporating Sr layers (typical thickness: 4 nm) on clean Si(1 0 0). For both CO2 and H2O the interaction is initiated by the dissociation of the molecules and the formation of (Sr–O) bonds. Subsequently impinging CO2 molecules form carbonate complexes CO32− involving the (Sr–O) bonds. In the case of H2O the surface becomes largely covered by hydroxyls at larger exposures. These are formed by hydrogen abstraction from water occurring close to the (Sr–O) bonds.