H 2O adsorption on Ni(100): Evidence for oriented water dimers

Abstract

H 2O adsorption on clean Ni(110) surfaces at T ≦ 150 K leads at coverages below θ ≊ 0.5 to the formation of chemisorbed water dimers, bound to the Ni substrate via both oxygen atoms. The linear hydrogen bond axis is oriented parallel to the [001] surface directions. With increasing H 2O coverage (θ ≧ 0.5), the accumulation of further hydrogen bonded water molecules induces some modification of the dimer configuration, producing at θ ≊ 1 a two-dimensional hydrogen bonded network with a slightly distorted ice lattice structure and long range order.