The growth process of first water layer and crystalline ice on the Rh(111) surface

J Chem Phys. 2009 Jan 21;130(3):034706. doi: 10.1063/1.3060952.

Abstract

The adsorption states and growth process of the first layer and multilayer of water (D(2)O) on Rh(111) above 135 K were investigated using infrared reflection absorption spectroscopy (IRAS), temperature programed desorption, spot-profile-analysis low-energy electron diffraction, and scanning tunneling microscopy (STM). At the initial stage, water molecules form commensurate ( radical3x radical3)R30 degrees islands, whose size is limited for several hexagonal units; the average diameter is approximately 2.5 nm. This two-dimensional (2D) island includes D-down species, and free OD species exist at the island edge. With increasing coverage, the D-up species starts to appear in IRAS. At higher coverages, the 2D islands are connected in STM images. By the titration of Xe adsorption we estimated that the D-down domain occupies about 55% on Rh(111) at the saturation coverage. Further adsorption of water molecules forms three-dimensional ice crystallites on the first water layer; thus, the growth mode of crystalline water layers on Rh(111) is a Stranski-Krastanov type. We have found that an ice crystallite starts to grow on D-down domains and the D-down species do not reorient upon the formation of a crystalline ice.