Surface spectroscopy and temperature-programmed desorption studies of the interaction of water vapor with Ni₃(Al, Ti) (100) and (111) surfaces as a function of temperature

The interaction of water vapor with single crystal Ni₃(Al, Ti) has been studied with Auger electron spectroscopy, photoemission spectroscopy and thermal desorption. Water adsorbs molecularly onto the (111) and (100) surfaces at 140 K. When warmed up to room temperature, water remains as an intact molecule on (111), but dissociates to surface hydroxyl and atomic oxygen on (100). The latter process is accompanied by the evolution of hydrogen and oxidation of Al. It appears that the dissociation of water is structure-sensitive and that Al is the active species in controlling the dissociation of water on Ni₃Al surfaces.