title: Phenyl species formation and preferential hydrogen abstraction in the decomposition of chemisorbed benzoate on Cu(110).
abstract: The adsorption and decomposition of benzoic acid on the Cu(110) surface has been investigated using temperature-programmed reaction (TPR) spectroscopy and scanning tunneling microscopy (STM). The benzoate species is found to exist in two conformations--a phase containing upright species at monolayer saturation and a phase containing many lying-down species at lower coverages. Thermal decomposition begins to occur near 500 K, yielding benzene and CO(2). It is found that phenyl species, generated preferentially from the lying-down benzoate species, efficiently abstract H atoms from undecomposed benzoate species to produce benzene in a rate-controlling process with an activation energy of about 29 kcal/mol. Using deuterium-atom substitution at the 4-C position on the benzoate ring it is found that the hydrogen-abstraction reaction is selective for 2,3 and 5,6 C-H bonds. This observation indicates that the mobile phenyl species is surface bound and preferentially attacks C-H bonds which are nearest the Cu surface and bind the benzoate species as either an upright species or a tilted species.
authors.affiliation: Department of Chemistry, Surface Science Center, University of Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Junseok
authors.initials: J
authors.lastname: Lee
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Dougherty
authors.forename: John T
authors.initials: JT
authors.lastname: Yates