Electron-induced surface chemistry: Production and characterization of NH2 and NH species on Pt(111)

Irradiating molecularly adsorbed NH, with controlled fluences of 50 eV electrons on Pt(111) at 100 K leads to NH2, NH, and H species. Temperature programmed desorption shows dihydrogen desorption, confirming electron induced decomposition of ammonia, and a new NH3 desorption peak (210 K) attributed to hydrogenation of NH2. High resolution electron energy loss spectroscopy identifies NH2 through two vibrational features at 830 and 1392 cm(-1) that are assigned to rocking and wagging modes, and NH through a single strong stretching feature at 3280 cm(-1). NH was stable up to 400 K where it dehydrogenated, leaving N on the surface, which was stable up to 700 K. In x-ray photoelectron spectroscopy a N(1s) peak, shifted to lower binding energy, appears after electron irradiation. (C) 1996 American Vacuum Society.