Effect of Preadsorbed Oxygen on the Growth of Water Ice Multilayers on Cu(111)

The adsorption of water molecules on a substrate is influenced by the substrate-water interaction, as well as the H-bonding interactions between neighboring water molecules. The properties of the substrate can dictate the adsorption geometry of individual water molecules on the surface and the growth mechanism of the first layers of water. In this study, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) is used to explore how preadsorbed oxygen on a Cu(111) substrate affects the structure and growth of multilayer crystalline D₂O films. Differences in the intensity ratios of the OD symmetric and asymmetric stretch peaks (ν₁/ν₃) reveal that D₂O ices grown on Cu(111) precovered with oxygen (Cu(111)/O) are more orientationally ordered than those grown on bare Cu(111). A further comparison of the ν₁/ν₃ intensity ratios shows that the orientational ordering of the films differs from the earliest D₂O exposures, indicating that the surface properties dictate the arrangement of the D₂O film. The integrated IRRAS intensity of the OD stretch peaks reveals that the orientational order of D₂O ices grown on Cu(111)/O is preserved up to an exposure of 25 Langmuirs. These results demonstrate that changes in the surface properties can significantly alter the 3D structure of the resulting D₂O ices.