DIIMIDE FORMATION ON THE NI(100) SURFACE

Diimide (N2H2), an extremely reactive species, is observed as a gas ph ase product from the Ni(100) surface in the 200 to 450 K range during hydrazine thermal decomposition and during thermal desorption of predi ssociated ammonia. These results suggest that the primary mechanism fo r diimide formation is recombination of an adsorbed NH surface interme diate. The ohservation that diimide can be formed from predissociated ammonia illustrates that a nitrogen-nitrogen bond in the precursor is not required for diimide formation. Diimide formation from predissocia ted ammonia is enhanced by coadsorbed hydrogen, which we believe stabi lizes NH on the Ni(100) surface. In addition, the direct decomposition of adsorbed N2H4 contributes to the production of diimide at 230 K.