Angular-resolved photoemission from NH3 on Ni(110)

NH₃ adsorbed on Ni(110) at a temperature of 100 K has been studied by angular-resolved ultraviolet photoelectron spectroscopy (ARUPS) using synchrotron radiation in the energy range 10 ? ? ω ? 35 eV. From ARUPS it is concluded that NH₃ bonds via its nitrogen lone-pair orbital with its molecular axis normal to the surface. For both the 3a₁ and 1e level dispersion has been found indicating lateral interactions within a compact NH₃ layer. Increasing the NH₃ coverage beyond the chemisorbed monolayer produces a physisorbed monolayer followed by a multilayer deposition of NH₃ phase on top which has been identified by photoemission and thermal desorption. Desorption and partial decomposition result from annealing. At 300 K NH₃ or NH is left at the surface which desorbs almost completely by annealing to 400 K.