DIIMIDE FORMATION ON RHODIUM SURFACES - A TEMPERATURE-PROGRAMMED REACTION SPECTROSCOPY STUDY

Diimide (N2H2) formation has been detected as a gas-phase product over the 180-500 K temperature range from a clean rhodium surface during decomposition of both hydrazine and ammonia. The diimide was identified on the basis of mass spectrometry of the parent ion (30 amu) and a single-dehydrogenation fragmentation product (29 amu) that is 6% of the parent. The formation of diimide was confirmed chemically for both precursors by observing substantial increases in yield in the presence of coadsorbed hydrogen and a substantial decrease in the presence of coadsorbed oxygen. Adsorbed NH from N2H4 or NH3 decomposition is proposed as a potential surface intermediate.