Synchrotron Radiation FTIR Spectroscopic Studies of Water on Ni(110)

Abstract

The adsorption of water on Ni(110) at 92-230 K has been studied by Fourier transform infrared reflection-absorption spectroscopy (FTIR-RAS) in the 200-2000 cm-l frequency range using a synchrotron radiation source. For water adsorbed at 90-180 K and coverage θ(0≤θ≤0.5 monolayers), two IR bands at frequencies of ~ 667 and 806 cm-1 can always be observed despite the absence of an O–H stretch band. For water adsorbed at 180 K followed by annealing to 230 K, two IR bands are again observed, at 767 and 947 cm-1. In both cases we attribute the bands to water wagging and rocking modes. At 180 K, they are rather broad and indicative of interactions in the ordered c (2 × 2) water layer; long range dipole–dipole interactions could be important in stabilizing this 0.5 ML structure at 180 K. At 230 K the bands are believed to originate from the water molecules in water-hydroxyl complexes which occur in well-ordered 2 × 1 islands.