Bond breaking in vibrationally excited methane on transition-metal catalysts

Jansen, Apj Tonek

doi:10.1103/physrevb.61.15657

Cited by 53 publications

(39 citation statements)

References 22 publications

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“…Calculations reveal significant and mode-selective softening as the molecule approaches the surface. 39,61,62 This behavior may tune or detune resonances between the initial state and the doorway states and impact the initial rate of IVR, but energy flow via loworder coupling into the doorway states will still dominate the initial stages of IVR. Recent high-level calculations of methane activation are consistent with this general propensity.…”

Section: Resultsmentioning

confidence: 99%

On the origin of mode- and bond-selectivity in vibrationally mediated reactions on surfaces

Killelea

Utz

2013

Phys. Chem. Chem. Phys.

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On the origin of mode-and bond-selectivity in vibrationally mediated reactions on surfaces. Physical Chemistry Chemical Physics, 15, 47: 20545-20554, 2013 The experimental observations of vibrational mode-and bond-selective chemistry at the gas-surface interface indicate that energy redistribution within the reaction complex is not statistical on the timescale of reaction. Such behavior is a key prerequisite for efforts to use selective vibrational excitation to control chemistry at the technologically important gas-surface interface. This paper outlines a framework for understanding the origin of non-statistical reactivity on surfaces. The model focuses on the kinetic competition between intramolecular vibrational energy redistribution (IVR) within the reaction complex, which in the long-time limit leads to statistical behavior, and quenching, scattering, or desorption processes that restrict the extent of IVR prior to reaction. Characteristic timescales for these processes drawn from studies of vibrational energy flow dynamics on surfaces and in the gas and condensed phases suggest that IVR is severely limited for important classes of surface reactions. Under these conditions, selective vibrational excitation can lead to preferential transition state access and result in mode-or bond-selective chemistry, even at high collision energies above the barrier to reaction. In addition to providing a basis for understanding experimental observations, the model provides guidance for identifying other gas-surface reactions that may exhibit mode-selective behavior.

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Section: Resultsmentioning

confidence: 99%

On the origin of mode- and bond-selectivity in vibrationally mediated reactions on surfaces

Killelea

Utz

2013

Phys. Chem. Chem. Phys.

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“…From our wave packet simulations we know that vibrational excitations can contribute to a strong enhancement of vibrational inelastic scattering. 23 So the actual effect of raising the nozzle temperature can be different than sketched here.…”

Section: Nozzle Temperaturementioning

confidence: 97%

“…Let us now compare the full classical dynamics with our fixed oriented wave packet simulations, [21][22][23] because this was initially the reason to perform the classical dynamics simulations. Again we observe very little vibrational inelastic scattering.…”

Section: Wave Packet Simulationsmentioning

confidence: 99%

“…Later on we reported on wave packet simulations of the role of vibrational excitations for the scattering of CH 4 and CD 4 . 23 We predicted that initial vibrational excitations of the asymmetrical stretch ( 3 ) but especially the symmetrical stretch ( 1 ) modes will give the highest enhancement of the dissociation probability of methane. Although we have performed these wave packet simulations in ten dimensions, we still had to neglect two translational and three rotational coordinates of the methane molecule and did not account for surface motion and corrugation.…”

Section: Introductionmentioning

confidence: 99%

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Energy dissipation and scattering angle distribution analysis of the classical trajectory calculations of methane scattering from a Ni(111) surface

Kleyn

Jansen

2001

The Journal of Chemical Physics

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We present classical trajectory calculations of the rotational vibrational scattering of a nonrigid methane molecule from a Ni(111) surface. Energy dissipation and scattering angles have been studied as a function of the translational kinetic energy, the incidence angle, the (rotational) nozzle temperature, and the surface temperature. Scattering angles are somewhat toward the surface for the incidence angles of 30°, 45°, and 60° at a translational energy of 96 kJ/mol. Energy loss is primarily from the normal component of the translational energy. It is transferred for somewhat more than half to the surface and the rest is transferred mostly to rotational motion. The spread in the change of translational energy has a basis in the spread of the transfer to rotational energy, and can be enhanced by raising of the surface temperature through the transfer process to the surface motion.

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“…In the case of CH 4 , for example, 15 degrees of freedom are needed on a rigid surface, rendering it difficult to develop an accurate, global high-dimensional PES (32)(33)(34) and to carry out quantum dynamical calculations. Thus far, most dynamical studies involved low-dimensional models (35)(36)(37)(38)(39)(40)(41) and fell short of providing a complete understanding of the complex dynamics. Water dissociative chemisorption, on the other hand, requires nine dimensions, and is thus significantly less demanding.…”

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confidence: 99%

Enhancing dissociative chemisorption of H ₂ O on Cu(111) via vibrational excitation

Jiang

Ren

Xie

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

117

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The dissociative chemisorption of water is an important step in many heterogeneous catalytic processes. Here, the mode selectivity of this process was examined quantum mechanically on a realistic potential energy surface determined by fitting planewave density functional calculations spanning a large configuration space. The quantum dynamics of the surface reaction were characterized by a six-dimensional model including all important internal coordinates of H 2 O and its distance to the surface. It was found that excitations in all three vibrational modes are capable of enhancing reactivity more effectively than increasing translational energy, consistent with the "late" transition state in the reaction path.heterogeneous catalysis | mode specific chemistry | reaction dynamics T he dissociative chemisorption of H 2 O on transition-metal surfaces, which produces chemisorbed H and OH species, is an important and often obligatory step in many heterogeneous catalytic processes, such as the water-gas shift (WGS) reaction and steam reforming (1). Given our dwindling fossil fuel resources and health-threatening pollution, these reactions have become increasingly important in generating environmentally friendly hydrogen fuels for various high-efficiency applications, such as fuel cells (2). In low-temperature WGS on copper catalysts, for example, the dissociative chemisorption of H 2 O has been identified as the rate-limiting step (3). A better understanding of the reaction dynamics and the ultimate control and/or enhancement of the process could potentially benefit many industrial processes that involve H 2 O. Despite our increasing understanding of the adsorption and dissociation of water on various metal surfaces, however, few experimental studies have been reported (to the best of our knowledge) on the dynamics of water-metal interaction, and none on dissociative chemisorption (4). In this work, we explore a potentially useful scheme based on mode selectivity to enhance dissociative chemisorption on a copper surface.Controlling reactivity of a chemical reaction by selecting reactant internal quantum states is a holy grail in chemical dynamics (5). This mode selectivity and related bond selectivity have been experimentally demonstrated for only a few reactive systems in the gas phase (6-13) and on surfaces (14-21). For example, it was shown that both the kinetics and dynamics of the H þ H 2 O reaction depend sensitively on the vibrational state of the H 2 O reactant (6). Similarly, different vibrational excitations of CH 4 have been demonstrated to have varying efficacies in promoting its dissociative chemisorption on transition-metal surfaces, some more effective than translational energy (22). These observations underscore the importance of quantum dynamical effects and inadequacy of statistically based transition state theory for describing mode-and bond-specific chemistry.A key question in mode-and bond-selective chemistry is whether energy in vibrational coordinates is more effective in promoting reaction than t...

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Bond breaking in vibrationally excited methane on transition-metal catalysts

Cited by 53 publications

References 22 publications

On the origin of mode- and bond-selectivity in vibrationally mediated reactions on surfaces

On the origin of mode- and bond-selectivity in vibrationally mediated reactions on surfaces

Energy dissipation and scattering angle distribution analysis of the classical trajectory calculations of methane scattering from a Ni(111) surface

Enhancing dissociative chemisorption of H ₂ O on Cu(111) via vibrational excitation

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Bond breaking in vibrationally excited methane on transition-metal catalysts

Cited by 53 publications

References 22 publications

On the origin of mode- and bond-selectivity in vibrationally mediated reactions on surfaces

On the origin of mode- and bond-selectivity in vibrationally mediated reactions on surfaces

Energy dissipation and scattering angle distribution analysis of the classical trajectory calculations of methane scattering from a Ni(111) surface

Enhancing dissociative chemisorption of H 2 O on Cu(111) via vibrational excitation

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Enhancing dissociative chemisorption of H ₂ O on Cu(111) via vibrational excitation