Adsorption on Niobium (110), Tantalum (110), and Vanadium (110) Surfaces

Abstract

Clean surfaces of Nb (110), Ta (110), and V (110) have been prepared by heating in an ultrahigh-vacuum environment. Low-energy, electron-diffraction measurements indicated that all clean surfaces were the same as an ideal (110) plane in the bulk to within experimental error. Adsorption of CO and O2 on the clean surfaces of these metals led to similar patterns suggesting that the same structures formed on all three metals. The patterns obtained from adsorption of CO followed by warming to about 400°C were the same as those obtained by room-temperature exposure to O2. This suggests decomposition of the adsorbed CO. At least three different structures of O2 on these metals are produced as coverage is increased. Unfortunately, dissolution of the O2 into the bulk prevents accurate determination of surface coverage and this, coupled with the inability to handle intensity-distribution curves effectively, has made complete structure determinations of these oxides impossible.