title: The role of Oad in the decomposition of NH3 adsorbed on Ir(110): a combined TPD and high-energy resolution fast XPS study.
abstract: High energy resolution fast XPS combined with TPD experiments were used to study the effect of chemisorbed oxygen on the adsorption and dissociation of NH(3) on Ir(110). Below 250 K the presence of O(ad) does not influence NH(3) decomposition. Above 250 K O(ad) enhances NH(3) dissociation, which results in three times as much N(2) formation and less molecular NH(3) desorption compared to the experiments without O(ad). The effect of O(ad) can be attributed to destabilization of NH(ad) on the surface, resulting in a further dehydrogenation towards N(ad). The presence of O(ad) on the surface lowers the temperature at which the N(ad) combination reaction takes place by as much as 200 K, due to repulsive interaction between N(ad) and O(ad). NO is formed above 450 K if both N(ad) and O(ad) are present on the surface.
authors.affiliation: Leids instituut voor chemisch onderzoek, Universiteit Leiden, P.O. Box 9502, Einsteinweg 55, 2300 RA Leiden, The Netherlands.
authors.forename: C J
authors.initials: CJ
authors.lastname: Weststrate
authors.forename: J W
authors.initials: JW
authors.lastname: Bakker
authors.forename: E D L
authors.initials: ED
authors.lastname: Rienks
authors.forename: C P
authors.initials: CP
authors.lastname: Vinod
authors.forename: S
authors.initials: S
authors.lastname: Lizzit
authors.forename: L
authors.initials: L
authors.lastname: Petaccia
authors.forename: A
authors.initials: A
authors.lastname: Baraldi
authors.forename: B E
authors.initials: BE
authors.lastname: Nieuwenhuys
mesh_terms: D000327:Adsorption; D000641:Ammonia / Q000737:chemistry*; D004055:Differential Thermal Analysis / Q000379:methods; D007495:Iridium / Q000737:chemistry*; D009569:Nitric Oxide / Q000138:chemical synthesis; D010100:Oxygen / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission / Q000379:methods; D013499:Surface Properties; D013696:Temperature
chemical_list: D009569:Nitric Oxide; D007495:Iridium; D000641:Ammonia; D010100:Oxygen