Synchrotron radiation FTIR spectroscopic studies of water on Ni(110)

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(-1) frequency range using a synchrotron radiation source. For water adsorbed at 90-180 K and coverage theta (0 less than or equal to theta less than or equal to 0.5 monolayers), two IR bands at frequencies of similar to 667 and similar to 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 x 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 x 1 islands.