Structural phenomena related to associative and dissociative adsorption of water on Ni(110)

The adsorption of water on Ni(110) has been studied by thermal desorption spectroscopy (TDS), work function (ΔΦ), Fourier transform infrared reflection–absorption spectroscopy (FTIR-RAS), low energy electron diffraction (LEED), and electron-stimulated desorption ion angular distribution (ESDIAD). The major findings of this study are the following: (1) Water molecules in the chemisorbed c(2×2) half-monolayer do not cluster and the plane of the molecules is highly inclined to the surface normal; (2) no ESDIAD evidence of oriented water dimers is observed at 130 K and no FTIR activity is observed following adsorption at 80 K until multilayers are populated; (3) water has been measured to partially dissociate at a minimum temperature of 205±2 K; (4)the binding energy of water to the Ni(110) surface is increased by H-bonding to adsorbed hydroxyls (produced by the partial dissociation) in a linear OH(ad)/H2O complex with planar symmetry in the [001] direction. This bonding results in a higher temperature desorption state (A1).