STABLE AND METASTABLE PHASES OF WATER ADSORBED ON CU(111)

Metastable and stable phases of water adsorbed at low coverages on Cu(111) were studied using vibrational spectroscopy (both time-resolved and high-resolution electron energy-loss spectroscopies) and temperature programmed desorption. The two water species have distinct spectroscopic signatures and different desorption kinetics. The more stable species appears to be three-dimensional clusters of bulklike, polycrystalline ice while the metastable species was observed to have a higher desorption rate despite a larger activation enthalpy for desorption. A simple model is proposed to explain this intriguing result. The conversion from the metastable to the stable species, as well as the affects of preadsorbed carbon monoxide on the adsorption/desorption kinetics, are also discussed.