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  • 1
    Electronic Resource
    Electronic Resource
    Quantum-mechanical scattering of H2 from metal surfaces: Diffraction and dissociative adsorption (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 7197-7208 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Some theoretical and experimental aspects of the interaction of H2 with metal surfaces are reviewed. A variety of model potential energy surfaces based on simple extensions to the Lennard-Jones model are presented. These potentials include activation barriers which vary across the surface unit cell giving rise to a variety of physically interesting and realistic topologies. The quantum-mechanical scattering of hydrogen and its isotopes from these potentials illustrate that it is possible, in a very simple way, to account for simultaneous sticking and diffraction at a single beam energy. The inclusion of tunneling in a realistic description of initial sticking coefficients is shown to be essential for these light gases. Finally, it is proposed that by inverting diffraction data, it should be possible to obtain key information regarding the form of the potential energy surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454372
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  • 2
    Electronic Resource
    Electronic Resource
    The loss of memory in the trapping of Ar/Pt(111) (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 806-807 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460299
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of potential energy surface topologies on the dissociation of H2 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 2859-2870 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this work we present a theoretical study of the dissociative adsorption of hydrogen molecules from a series of model potential energy surfaces. The aim is to discover those particular topological features in the potential surface which are responsible for determining the vibrational state-to-state cross sections in both the dissociated and the scattered flux. The potential energy surface is two-dimensional, and is chosen to be deliberately simple; a combination of Morse potentials and a Gaussian barrier. A quantum wave packet is chosen to represent the molecule and the dynamics are solved by a spectral grid method. Results show that the location of the barrier influences the scattering cross sections markedly. Early barriers result in vibrationally excited adsorbed species while late barriers produce translationally hot atoms. The individual state distributions resulting from the two model potentials are quite different. In addition, results are given for a potential where the activation barrier is deep in the exit channel. For this case, results show that molecules can trap near the barrier for significant times without invoking substrate degrees of freedom. This is explained in terms of trapping in dynamic wells. Finally, we assess the effect on dissociation probability following vibrational excitation of the hydrogen molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458871
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  • 4
    Electronic Resource
    Electronic Resource
    A theoretical study of the dissociation of H2/Cu (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 7209-7219 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present calculations for the dissociative adsorption of hydrogen molecules on a Cu surface as a function of initial translational energy and vibrational quantum state. Classical, semiclassical, and fully quantum calculations are performed and the results compared. The potential energy surface was based upon a total energy calculation for H2 on a small Cu cluster and has been previously employed in dynamical simulations. Our results show that for low primary beam energies, dissociation occurs primarily via tunneling through the activation barrier in the vibrational coordinate. Populating the initial vibrational states is shown to enhance reactivity, but not simply by a total energy shift. By changing the hydrogen isotope it is shown that tunneling effects can persist up to quite high molecular masses. This occurs because the activation barrier lies in the vibrational coordinate, where the reduced mass of the molecule determines the dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457288
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  • 5
    Electronic Resource
    Electronic Resource
    Resonance-mediated dissociative adsorption of hydrogen (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 9145-9156 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Selective adsorption has been examined theoretically using time-dependent quantum-mechanical methods. In the simple case of a potential with no open channel to dissociation, we find that the description in terms of bound states of the laterally averaged potential holds, and perturbation theory gives adequate results for the lifetimes of the states. A more complicated situation, in which dissociation and resonance interact strongly, is beyond the reach of perturbation theory. Nevertheless, the resonances still exist at energies determined by kinematics. They decay more rapidly than before into both the dissociation and scattering channels. The most striking feature of the results is that the dissociation probability, as well as the diffraction intensities, exhibits a Fano profile around the resonance. Thus resonance diminished dissociation can be seen. We examine the possible inclusion of inelastic effects in our calculations, and the direct comparison with experiment this would allow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459204
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  • 6
    Electronic Resource
    Electronic Resource
    Dissociation dynamics from a de Broglie–Bohm perspective (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 10373-10381 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Within the framework of Bohm's reformulation of quantum physics we revisit the activated dissociation of hydrogen molecules at metal surfaces. The quantum-mechanical force, which accounts for most of quantum effects in the method, and is caused by nonlocal, topographical properties of the wave function, is computed using time-dependent wave packets obtained using conventional, spectral methods. Driven by a combination of the classical force together with the quantum force, trajectories carrying probability density either succeed in overcoming the barrier for dissociation or are scattered back into the gas phase. The Bohmian picture for the dissociation process has enabled us to develop a novel mechanism to account for vibrationally enhanced molecular dissociation. This is relevant to the recently observed promotion of dissociation of very highly vibrationally excited NO molecules at Cu surfaces. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1415450
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  • 7
    Electronic Resource
    Electronic Resource
    Charge transfer, vibrational excitation, and dissociative adsorption in molecule–surface collisions: Classical trajectory theory (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 5203-5215 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The consequences of charge transfer processes occurring when a molecular beam of diatomic molecules is directed upon a solid surface are here considered. In analogy with resonance electron scattering from molecules or harpooning processes in atom–diatom collisions, the incident beam could either be scattered into a highly vibrationally excited molecular state, dissociatively scattered, or dissociatively adsorbed due to formation of temporary negative molecular ions which enable redistribution of the incident translation energy of the beam into intramolecular degrees of freedom. In this work, the exact classical trajectories for the diatomic molecule, including internal vibrational motion, are calculated for motion over model diabatic potential surfaces in which surface hopping due to charge transfer/harpooning is accounted for. Connections between classes of trajectories and topological features of the potential energy surfaces (PES) are illustrated. The model is used to study the average translational to vibrational energy transfer as a function of incident kinetic energy and of PES parameters. Branching ratios between scattered and dissociatively adsorbed molecules are obtained as a function of both incident translational and total energy and the role of the intermediate negative ion resonance in influencing the dynamics of molecular processes at surfaces is illustrated. Comparison with quantum mechanical theories is given in a subsequent paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448645
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  • 8
    Electronic Resource
    Electronic Resource
    Changes in the vibrational frequencies of adsorbed molecules due to an applied electric field
    Amsterdam : Elsevier
    Journal of Electroanalytical Chemistry 161 (1984), S. 193-198 
    Details
    ISSN: 0368-1874
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0368-1874(84)83307-9
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  • 9
    Electronic Resource
    Electronic Resource
    Reflection high-energy electron diffraction from stepped surfaces
    Amsterdam : Elsevier
    Physics Letters A 71 (1979), S. 476-480 
    Details
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0375-9601(79)90641-8
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  • 10
    Electronic Resource
    Electronic Resource
    Reflection high-energy electron diffraction from an adsorbed monolayer
    Amsterdam : Elsevier
    Physics Letters A 71 (1979), S. 481-485 
    Details
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0375-9601(79)90642-X
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