Reaction kinetics of cerium thin films with H2, O2 and H2O systems at 298 K

Cerium (Ce) thin films were prepared under an ultra high vacuum condition, and each reactivity of H2, O2 or H2O with the Ce surface was quantitatively measured for the reaction probability r and the gas amount reacted at 298 K. A clean Ce surface exhibited the highest reactivity, r=1 for H2, O2 and H2O. Oxidized Ce surfaces exhibited higher reactivities with H2 than oxidized surfaces of other rare earths, La, Tb, Dy [1], however, the H2O preadsorption layers on the Ce surface strongly reduced H2 reactivities. CeH2+x hydride layers exhibit higher reactivities with O2 than the Ce oxide surface, suggesting a high metallic property of Ce hydride layers. © 2002 Elsevier Science B.V. All rights reserved.