title: Substrate Vibrations as Promoters of Chemical Reactivity on Metal Surfaces.
abstract: Studies exploring how vibrational energy (Evib) promotes chemical reactivity most often focus on molecular reagents, leaving the role of substrate atom motion in heterogeneous interfacial chemistry underexplored. This combined theoretical and experimental study of methane dissociation on Ni(111) shows that lattice atom motion modulates the reaction barrier height during each surface atom's vibrational period, which leads to a strong variation in the reaction probability (S0) with surface temperature (Tsurf). State-resolved beam-surface scattering studies at Tsurf = 90 K show a sharp threshold in S0 at translational energy (Etrans) = 42 kJ/mol. When Etrans decreases from 42 kJ/mol to 34 kJ/mol, S0 decreases 1000-fold at Tsurf = 90 K, but only 2-fold at Tsurf = 475 K. Results highlight the mechanism for this effect, provide benchmarks for DFT calculations, and suggest the potential importance of surface atom induced barrier height modulation in heterogeneously catalyzed reactions, particularly on structurally labile nanoscale particles and defect sites.
authors.affiliation: Department of Chemistry and W. M. Keck Foundation Laboratory for Materials Chemistry Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Campbell
authors.affiliation: Department of Chemistry and W. M. Keck Foundation Laboratory for Materials Chemistry Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
authors.forename: Han
authors.initials: H
authors.lastname: Guo
authors.affiliation: Department of Chemistry, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
authors.forename: Bret
authors.initials: B
authors.lastname: Jackson
authors.affiliation: Department of Chemistry and W. M. Keck Foundation Laboratory for Materials Chemistry Tufts University , Medford, Massachusetts 02155, United States.
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Utz