ADSORPTION AND REACTION OF WATER ON OXYGEN PRECOVERED CU(100)

The reaction of water with a fractional (<0.5) monolayer of oxygen on Cu(100) at 120 K has been studied using high resolution electron energy loss spectroscopy (HREELS) and work function measurements (DELTAphi). Two major species were found. The prevalent species (gamma) is formed for a wide range of oxygen precoverages and desorbs at approximately 220 K. This gamma species shows typical tilted OH vibrational modes in HREELS and is attributed to OH due to the dissociation of H2O. The second species (delta) is only dominant at low oxygen precoverage and desorbs between 255 and 300 K. It is characterized by at least three HREELS peaks at 420, 1170, and 3590 cm-1 and its formation is accompanied by a significant work function decrease. Its precise composition is not certain, but it is proposed to be a complex which involves molecular water.