UV Photodesorption of Novel Molecular Beam Induced NO Layers on NiO(111)/Ni(111)

Abstract

The photodesorption and photoreactivity of the molecular beam dosed NO/NiO(111)/Ni(111) system has been examined using high-resolution electron energy loss spectroscopy (HREELS). The molecular beam dosed surface exhibits three major vibrational peaks, which we attribute to a linear bonding NO species at 230 meV, a bent bonding NO species at 197 meV, and a stretching mode of NO 2 at 160 meV. UV photon irradiation causes the attenuation of these peaks accompanied by simultaneous emergence of a fourth vibrational peak at 215 meV. The emergence of this peak is explained by a mechanism of selective desorption of the original, linear-bound NO species and a reaccommodation of the beam-induced, bent NO structure to a new state on the lower coverage surface. The measured desorption cross sections and wavelength dependence are consistent with those of other studies of photochemical processes on such interfaces, indicating that photoinduced electron transfer from the substrate to the adsorbate is the mechanism responsible for the observed behavior.