The dynamics and origin of NO photodesorbed from NO/Ag(111)

The photochemistry of the NO/Ag(111) system has been studied by time-of-fli ght, photon-induced desorption and temperature-programmed desorption measur ements. It is shown that two species are photoactive for NO desorption, one of which had previously been thought photoinactive. The time-of-flight (TO F) data show that NO is desorbed from both sites by a photochemical mechani sm. This allows the previously unassigned high-temperature desorption of NO detected in temperature-programmed desorption to be assigned to a new form of adsorbed NO. In addition, the temperature-programmed desorption measure ments show that there: are a range of inter-adsorbate interactions on the s urface. Hence, the surface should not be thought of as comprising a range o f non-interacting adsorbates. (C) 2000 Elsevier Science B.V. All rights res erved.