Interaction of N2 with Re(1120) in the presence of H2

Abstract The effect of coadsorbed hydrogen on the molecular physisorption and dissociation of N 2 on Re(11 2 0) was studied under UHV conditions. It was found that the hydrogen blocks selectively the less tightly bound molecular physisorption site, α 1 . This blocking has no effect on the dissociation of N 2 on this surface. The barrier of dissociative adsorption of N 2 in the presence of coadsorbed hydrogen was determined to be 2.1± 0.4 kcal/mole. In contrast to the effect of hydrogen, CO preadsorption was found to reduce the population of the N 2 -α 2 physisorption site, and also to decrease the probability for nitrogen dissociation, These results imply that α 2 is a direct molecular precursor for the dissociative adsorption of N 2 on Re(11 2 0).