Browsing by Author "Jackson, Bret"

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Citation Count: Boyukata, M...et al. "Dynamics of the D(2)+Ni(100) collision system: Analysis of the reactive and inelastic channels" 3rd European Conference on Computational Chemistry, Vol.84, No.1, pp.48-57, (2001).
Dynamics of the D(2)+Ni(100) collision system: Analysis of the reactive and inelastic channels
(Wiley-Blackwell, 2001) Böyükata, Mustafa; Güvenç, Büşra; Jackson, Bret; Jellinek, Johanna
The reactive and scattering channels of the D(2)(v, j) + Ni(100) collision system are studied using quasiclassical molecular dynamics simulations. The interaction between the D(2) and the atoms of the surface is modeled by a LEPS (London-Eyring-Polani-Sato) potential energy function. The molecule is aimed at three different impact sites (atop, bridge, and center) of a rigid Ni(100) surface along the normal direction with various collision energies less than or equal to1.0 eV. Dissociative chemisorption probabilities are computed for different rotational states of the molecule. Probability distributions of the final rovibrational states of the ground-state Dp molecule scattered from those impact sites are also computed as a function of the collision energy. Higher collision energy results in excitation of higher rotational and/or vibrational states of the scattered molecule. At collision energies below 0.1 eV an indirect dissociation mechanism (through molecular adsorption) dominates the reaction. (C) 2001 John Wiley & Sons, Inc.
Citation Count: Güvenç, Ziya B.; Sha, XW.; Jackson B., "Eley-Rideal and hot atom reactions between hydrogen atoms on Ni(100): electronic structure and quasiclassical studies" Journal of Chemical Physics, Vol.115, No.19, pp.9018-9027, (2001).
Eley-Rideal and hot atom reactions between hydrogen atoms on Ni(100): electronic structure and quasiclassical studies
(Amer Inst Physics, 2001) Güvenç, Ziya B.; Sha, Xianwei; Jackson, Bret
The reactions of gas-phase H (or D) atoms with D (or H) atoms adsorbed onto a Ni(100) surface are studied. Electronic structure calculations based on density functional theory are used to examine the interaction of H atoms with the Ni(100) surface, as well as the interactions between two H atoms near the metal surface. A model potential-energy surface based on ideas from effective medium theory is fit to the results of these electronic structure calculations. Quasiclassical trajectory methods are used to simulate the interaction of low energy H and D atom beams with H and D-covered Ni(100) surfaces. It is found that hot-atom processes dominate the formation of molecular hydrogen. The distribution of energy in the product molecules is examined with regard to the various pathways available for reaction. The initial adsorbate coverage is varied and is shown to control the relative amounts of reflection, reaction, sticking, and subsurface penetration. Our results are compared with those from similar studies on Cu(111) and available experimental data for Ni(100). (C) 2001 American Institute of Physics.
Citation Count: Jackson, B.; Sha, XW.; Güvenç, Ziya B., "Kinetic model for Eley-Rideal and hot atom reactions between H atoms on metal surfaces" Journal of Chemical Physics, Vol.116, No.6, pp.2599-2608, (2002).
Kinetic model for Eley-Rideal and hot atom reactions between H atoms on metal surfaces
(Amer Inst Physics, 2002) Jackson, Bret; Sha, Xianwei; Güvenç, Ziya B.
A simple kinetic model is used to describe the interaction of H and D atomic beams with H- and D-covered metal surfaces. The atoms incident from the gas phase can have a direct Eley-Rideal reaction with an adsorbate, reflect, penetrate into the bulk, knock an adsorbate out of its binding site, or trap to form a hot atom. These hot mobile atoms can go on to react with other adsorbates, or eventually relax and stick. A coarse-graining approach, which takes advantage of the large difference between the time scales for the kinetics experiments and the reaction dynamics, allows us to derive relatively simple kinetic equations for reaction rates and coverages. The approach is similar to a kinetic random walk model developed by Kuppers and co-workers [J. Phys. Chem. 109, 4071 (1998)] except that our equations can be used to derive analytical expressions for saturation coverages, rates, and yields. The model is applied to the case of H atom reactions on a Ni(100) surface, and a detailed comparison is made with both experimental and quasiclassical studies. (C) 2002 American Institute of Physics.
Citation Count: Güvenç, Ziya B.; Sha, XW; Jackson B., "The effects of lattice motion on Eley-Rideal and hot atom reactions: Quasiclassical studies of hydrogen recombination on Ni(100)" Journal of Physical Chemistry B, Vol.106, No.33, pp.8342-8348, (2002).
The effects of lattice motion on Eley-Rideal and hot atom reactions: Quasiclassical studies of hydrogen recombination on Ni(100)
(Amer Chemical Soc, 2002) Güvenç, Ziya B.; Sha, Xianwei; Jackson, Bret
Quasiclassical methods are used to simulate the interactions of H or D atom beams with D- or H-covered Ni(100) surfaces. The Ni substrate is treated as a multilayer slab, and the Ni atoms are allowed to move. The model potential energy surface is fit to the results of detailed total-energy calculations based on density functional theory. Most of the incident atoms trap to form hot atoms, which can eventually react with an adsorbate, or dissipate their energy and stick. The incident atom is found to lose several tenths of an eV of energy into the metal, upon initially colliding with the surface. This limits reflection to a few percent, at all coverages, and secondary reactions between adsorbates are significantly lowered. Long time hot atom reactions are also found to be damped out by the inclusion of lattice motion, leading to increased sticking, even at high coverages where dissipation into the adsorbates should be the primary energy loss mechanism. Overall, the inclusion of lattice motion is found to improve agreement with experiment.