Surface Temperature Effects on the Dynamics of N₂ Eley-Rideal Recombination on W(100)

Quasiclassical trajectories simulations are performed to study the influence of surface temperature on the dynamics of a N atom colliding a N-preadsorbed W(100) surface under normal incidence. A generalized Langevin surface oscillator scheme is used to allow energy transfer between the nitrogen atoms and the surface. The influence of the surface temperature on the N2 formed molecules via Eley-Rideal recombination is analyzed at T = 300, 800, and 1500 K. Ro-vibrational distributions of the N2 molecules are only slightly affected by the presence of the thermal bath whereas kinetic energy is rather strongly decreased when going from a static surface model to a moving surface one. In terms of reactivity, the moving surface model leads to an increase of atomic trapping cross section yielding to an increase of the so-called hot atoms population and a decrease of the direct Eley-Rideal cross section. The energy exchange between the surface and the nitrogen atoms is semi-quantitatively interpreted by a simple binary collision model

Dynamical Reaction Pathways in Eley-Rideal Recombination of Nitrogen from W(100)

The scattering of atomic nitrogen over a N-pre-adsorbed W(100) surface is theoretically described in the case of normal incidence off a single adsorbate. Dynamical reaction mechanisms, in particular Eley-Rideal (ER) abstraction, are scrutinized in the 0.1-3.0 eV collision energy range and the influence of temperature on reactivity is considered between 300 and 1500 K. Dynamics simulations suggest that, though non-activated reaction pathways exist, the abstraction process exhibits a significant collision energy threshold (0.5 eV). Such a feature, which has not been reported so far in the literature, is the consequence of a repulsive interaction between the impinging and the pre-adsorbed nitrogens along with a strong attraction towards the tungsten atoms. Above threshold, the cross section for ER reaction is found one order of magnitude lower than the one for hot-atoms formation. The abstraction process involves the collision of the impinging atom with the surface prior to reaction but temperature effects, when modeled via a generalized Langevin oscillator model, do not affect significantly reactivity

Dynamics of H2 Eley-Rideal abstraction from W(110): Sensitivity to the representation of the molecule-surface potential

Dynamics of the Eley-Rideal (ER) abstraction of H2 from W(110) is analyzed by means of quasi-classical trajectory calculations. Simulations are based on two different molecule-surface potential energy surfaces (PES) constructed from Density Functional Theory results. One PES is obtained by fitting, using a Flexible Periodic London-Eyring-Polanyi-Sato (FPLEPS) functional form, and the other by interpolation through the corrugation reducing procedure (CRP). Then, the present study allows us to elucidate the ER dynamics sensitivity on the PES representation. Despite some sizable discrepancies between both H+H/W(110) PESs, the obtained projectile-energy dependence of the total ER cross sections are qualitatively very similar ensuring that the main physical ingredients are captured in both PES models. The obtained distributions of the final energy among the different molecular degrees of freedom barely depend on the PES model, being most likely determined by the reaction exothermicity. Therefore, a reasonably good agreement with the measured final vibrational state distribution is observed in spite of the pressure and material gaps between theoretical and experimental conditions.Fil: Petuya, R.. Universite de Bordeaux; Francia. Centre National de la Recherche Scientifique. Institut des Sciences Moléculaires; FranciaFil: Larregaray, P.. Universite de Bordeaux; Francia. Centre National de la Recherche Scientifique. Institut des Sciences Moléculaires; FranciaFil: Crespos, C.. Universite de Bordeaux; Francia. Centre National de la Recherche Scientifique. Institut des Sciences Moléculaires; FranciaFil: Busnengo, Heriberto Fabio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Martinez, Alejandra Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentin

Influence of Surface Symmetry on the Onset of Nitrogen Eley-Rideal Recombination on Tungsten

Classical trajectory simulations, using potential energy surfaces of ab initio quality, are performed to investigate the influence of crystal symmetry on the Eley-Rideal abstraction dynamics of N atoms colliding, under normal incidence, N-preadsorbed tungsten (100) and (110) surfaces. Low-energy reactivity (\u3c0.5 eV collision energy) results much higher for the (110) crystallographic plane. Such a feature stems from the topology of the interactions upon approach of the N-gas atom toward the N adsorbate: the strong lateral corrugation responsible for a significant threshold for recombination on the (100) surface is much smoother on the (110) plane, allowing low-energy incident atoms to react. Temperature is found to only slightly affect reactivity

Chemical reaction thresholds according to classical-limit quantum dynamics

International audienceClassical-limit quantum dynamics is used to explain the origin of the quantum thresholds of chemical reactions from their classical dynamics when these are vibrationally nonadiabatic across the interaction region. This study is performed within the framework of an elementary model of chemical reaction that mimics the passage from the free rotation of the reagents to the bending vibration at the transition state to the free rotation of the products

Dynamics of dissociative chemisorption of O2 on Cu(100) surface: A theoretical study

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Classical Molecule–Surface Scattering in a Quantum Spirit: Application to H 2 /Pd(111) Nonactivated Sticking

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Application of the modified Shepard interpolation method to the determination of the potential energy surface for a molecule�surface reaction: H 2 + Pt(111)

The technique to determine the potential energy surface (PES) for a molecule-surface reaction was presented using modified Shepard (MS) interpolation method. The efficiency and accuracy of the interpolation method for an activated multidimensional molecule-surface reactive problem was also analyzed. The efficiency of the interpolation method was tested by using an already existing PES to provide the input data required for the concentration of the new PES. It was shown that the MS interpolation method could be used efficiently to yield accurate PES for activated molecule-surface reactions

Comparative Theoretical Study of H₂ Eley-Rideal Recombination Dynamics on W(100) and W(110)

Quasiclassical molecular dynamics simulations are performed to study the Eley-Rideal recombination of H2 on two crystallographic planes of tungsten. Potential energy surfaces, based on density functional theory, are used to describe the H+H/W(100, 110) interactions. The calculations are carried out within the single adsorbate limit under normal incidence of the impinging H atoms. The influence of the crystallographic anisotropy on reaction cross sections and energy distribution of the formed molecules is analyzed in detail. Despite some discrepancies in the dynamics of recombination between W(100) and W(110) surfaces, translational, rotational, and vibrational energies of the formed molecules do not depend significantly on surface symmetry. Vibrational distribution of formed H2 molecules are found in good agreement with experiments

Multi-dimensional potential energy surface determination by modified Shepard interpolation for a molecule�surface reaction: H 2 + Pt(111)

A modified Shepard interpolation method, developed for constructing potential energy surfaces (PESs) for gas phase reactions, has been adapted to generate PESs for molecule-surface reactions, and applied to the dissociative chemisorption of H2 on Pt(111). To provide a test of the method, the input data were taken from an existing PES. Reaction probabilities computed using classical and quantum dynamics on the new PES are in excellent agreement with results for the old PES, the construction of which required twice as many points. This shows that the modified Shepard interpolation method can be used efficiently to build PESs which yield accurate dynamics results for molecule-surface reactions