title: Atomic-Scale Dynamics of Surface-Catalyzed Hydrogenation/Dehydrogenation: NH on Pt(111).
abstract: Low-temperature scanning tunneling microscopy (LT-STM) was used to move hydrogen atoms and dissociate NH molecules on a Pt(111) surface covered with an ordered array of nitrogen atoms in a (2 × 2) structure. The N-covered Pt(111) surface was prepared by ammonia oxydehydrogenation, which was achieved by annealing an ammonia-oxygen overlayer to 400 K. Exposing the N-covered surface to H2(g) forms H atoms and NH molecules. The NH molecules occupy face-centered cubic hollow sites, while the H atoms occupy atop sites. The STM tip was used to dissociate NH and to induce hopping of H atoms. Action spectra consisting of the reaction yield versus applied bias voltage were recorded for both processes, which revealed that they are vibrationally mediated. The threshold voltages for NH dissociation and H hopping were found to be 430 and 272 meV, corresponding to the excitation energy of the N-H stretching and the Pt-H stretching modes, respectively. Substituting H with D results in an isotopic shift of -110 and -84 meV for the threshold voltages for ND dissociation and D hopping, respectively. This further supports the conclusion that these processes are vibrationally mediated.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago , 845 West Taylor Street, Chicago, Illinois 60607, United States.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Liang
authors.affiliation: Surface and Interface Science Laboratory, RIKEN , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Yang
authors.affiliation: Surface and Interface Science Laboratory, RIKEN , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Junepyo
authors.initials: J
authors.lastname: Oh
authors.affiliation: Surface and Interface Science Laboratory, RIKEN , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.|Department of Chemistry, University of Ulsan , 93 Daehak-ro, Nam-gu, Ulsan 680-749, Republic of Korea.
authors.forename: Jaehoon
authors.initials: J
authors.lastname: Jung
authors.affiliation: Surface and Interface Science Laboratory, RIKEN , 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Yousoo
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Chemistry, University of Illinois at Chicago , 845 West Taylor Street, Chicago, Illinois 60607, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Trenary
keywords: H hopping; NH dissociation; Pt(111); action spectroscopy; low-temperature scanning tunneling microscopy