Interaction of condensed water molecules with hydroxyl and hydrogen groups on Si(0Â 0Â 1)

Interaction of condensed water molecules with hydroxyl and hydrogen groups on Si(0 0 1) was investigated using high-resolution electron energy-loss spectroscopy (HREELS) in an ultrahigh vacuum system and also slab model calculations based on the density functional theory (DFT). Equal amounts of the hydroxyl and hydrogen groups were formed via dissociative adsorption of water molecules on a reconstructed Si(0 0 1)-(2 × 1) surface. The interaction between the hydroxyl group and condensed water molecules was clearly observed in vibrational peak shifts of the hydroxyl group, while the hydrogen group showed little interaction, reflecting its hydrophilic or hydrophobic property, respectively.