Classical dynamics study of atomic oxygen over graphite (0001) with new interpolated and analytical potential energy surfaces

Morón, Víctor; Martin-Gondre, L.; Larrégaray, P.; Gamallo, Pablo; Sayós, R.

doi:10.1016/j.comptc.2012.01.030

Cited by 23 publications

(45 citation statements)

References 55 publications

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“…This possible contribution is also plotted in Figure 6, which is peaked at much lower angles (θv' = 37°). However, in spite of the Eley-Rideal probability is high (i.e., 0.489) when an oxygen atom is preadsorbed over the unit cell at these hyperthermal conditions 9 , the necessary previous O adsorption step over a clean surface has a low probability (i.e., 0.0016). Therefore, the intensity of the Eley-Rideal contribution to the total polar scattering angular distribution should be in principle very small compared with that originated only by the scattered O2 molecules from the initial beam.…”

Section: B Hyperthermal Initial Conditionsmentioning

confidence: 98%

“…Periodic density functional theory calculations have been performed using the Vienna ab initio simulation package (VASP) 11,12,13,14 . All the details about the methodology used (e.g., GGA/RPBE functional, energy cut off, slab model, …) were discussed deeply in previous works 8,9,10 devoted to atomic oxygen interaction with both a clean and an O-preadsorbed graphite surfaces, and are omitted here. New DFT calculations have been performed in order to check the accuracy of the analytical FPLEPS PES in describing the O2/graphite interaction.…”

Section: B Dft Calculationsmentioning

confidence: 99%

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Dynamics of the Oxygen Molecules Scattered from the Graphite (0001) Surface and Comparison with Experimental Data

Morón¹,

Martin-Gondre

Gamallo³

et al. 2012

J. Phys. Chem. C

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A quasiclassical trajectory dynamics study of molecular oxygen colliding over a free of defects and clean graphite (0001) surface has been performed with a recently published density functional theory based flexible periodic London-Eyring-Polanyi-Sato potential energy surface (PES). Although the PES was mainly constructed for describing accurately the recombination of atomic oxygen over an Opreadsorbed surface, here we show that this PES is also reliable to study the scattering of O2 over graphite surface. Thus, several initial conditions have been explored: collision energies (0.2 £ Ecol £ 1.2 eV), incident angles (qv = 0°, 45°), surface temperatures (100 £ Tsurf £ 900 K) and some rovibrational O2 levels (v = 0,1,2 and j = 1,17,25). The calculated polar scattering angular distributions are in good agreement with the experimental ones in a wide range of explored conditions. Moreover, the comparison with hyperthermal experimental data, which was unclear in a previous work, has been finally clarified. The effect of O2 (v,j) internal state on the scattering is very small.

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Section: B Hyperthermal Initial Conditionsmentioning

confidence: 98%

Section: B Dft Calculationsmentioning

confidence: 99%

Dynamics of the Oxygen Molecules Scattered from the Graphite (0001) Surface and Comparison with Experimental Data

Morón¹,

Martin-Gondre

Gamallo³

et al. 2012

J. Phys. Chem. C

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“…12 These studies were performed for a single layer of graphene and few atoms (24 atoms). Morón et al 13 have studied oxygen collision using two grapheme layers, however, considered only two lattice units. The MD simulations of Srinivasan and vanDuin 12 did indicate that the simulation results would differ if a wider sheet was used, however, did not study this in detail.…”

Section: Introductionmentioning

confidence: 99%

Computational Chemistry Modeling of the Oxidation of Highly Oriented Pyrolytic Graphite

Poovathingal

Schwartzentruber²

2012

43rd AIAA Thermophysics Conference

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Large scale molecular dynamics (MD) simulations are performed to study the oxidation of Highly Oriented Pyrolytic Graphite (HOPG) by hyperthermal atomic oxygen beam (5eV). The simulations are performed using a classical reactive force field (ReaxFF) initially parameterized to accurately model hydrocarbon oxidation reactions. The MD simulations are compared to molecular beam experiments and good qualitative agreement is found. The simulations predict a cylindrical etch pit clearly observed in the experiments. The simulations demonstrate that oxidation is rapid and primarily occurs around defects in the graphene sheets. It is observed that the number of carbons atoms removed scales linearly with the number of oxygen atoms striking the etch pit. Furthermore, the simulations show an increase in oxidation as the surface temperature is increased. The qualitative agreement between MD simulations and experiment is encouraging and suggests that the interatomic potential used and oxidation simulation methodology described in this article are accurate and could potentially be used to study more complex surface oxidation processes relevant to hypersonic flight vehicles. Nomenclature ψ i reaction rate of reaction i ρ wO2 density of at the wall ρ wO density of O (atomic oxygen) at the wall M wO molecular mass of atomic oxygen M wO2 molecular mass of O 2 (molecular oxygen) R w universal gas constant T w wall Temperature α i reaction efficiency of reaction i c t average velocity of oxidized products leaving the surface k Boltzmann constant m mass of oxidized species in amu T temperature of the surface ν frequency of collisions per second σ T collision cross-section d ref reference diameter P steric factor for a reaction N Avagardo's constant m * reduced mass of reacting species n number density E a activation energy

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“…Characterization of O2-oxidized fibers using SEM [13] showed etch pits similar to those observed in the oxidation of HOPG [14]. Interest in graphene has prompted many experimental [15][16][17][18][19] and numerical [20][21][22][23][24] studies to examine the oxidation and reduction of HOPG and graphene oxide. Oxidation of HOPG by atomic oxygen has also been extensively studied to understand material degradation in low Earth orbit (LEO) [14,25,26].…”

Section: Introductionmentioning

confidence: 99%

Reactive and Inelastic Scattering Dynamics of Hyperthermal O and O2 from a Carbon Fiber Network

Poovathingal¹,

Qian²,

Murray³

et al. 2021

Preprint

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The reactive and inelastic scattering dynamics of ground-state atomic and molecular oxygen from a carbon fiber network at 1023-1823 K was investigated with a molecular beam-surface scattering technique. A molecular beam containing hyperthermal O and O2 with a mole ratio of 0.92:0.08 and nominal velocity of 8 km s-1 was directed at the network, and time-of-flight distributions of the scattered products were collected at various angles with the use of a rotatable mass spectrometer detector. O atoms exhibited both impulsive scattering (IS) and thermal desorption (TD) dynamics, where the TD O-atom flux increased with surface temperature and the IS O-atom flux remained relatively constant. While the majority of the TD O atoms desorbed promptly after the beam pulse struck the network, signatures of thermal processes occurring over long residence times were also observed. Evidence of O2 reactions was not observed, and the behavior of the inelastically scattered O2 was invariant to the temperature of the network and showed both IS and TD dynamics. The dominant reactive product was CO, whereas CO2 was a minor product. Both these products showed only TD dynamics. The observed flux of CO initially increased with temperature and then reached a plateau above which the flux no longer increased with temperature, over the temperature range studied. Thermally desorbed CO products exited the network promptly or after relatively long residence times, and two populations of CO with long residence times were distinguished. Hysteresis was observed in the temperature-dependent flux of thermally desorbed O and CO, with opposing trends for the two products. This work follows similar studies in our laboratory where the target materials were vitreous carbon and highly oriented pyrolytic graphite. The data suggest that the chemical reactivity of the three forms of sp2 carbon surfaces is similar and that the differences arise from the variations of the morphology.

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Classical dynamics study of atomic oxygen over graphite (0001) with new interpolated and analytical potential energy surfaces

Cited by 23 publications

References 55 publications

Dynamics of the Oxygen Molecules Scattered from the Graphite (0001) Surface and Comparison with Experimental Data

Dynamics of the Oxygen Molecules Scattered from the Graphite (0001) Surface and Comparison with Experimental Data

Computational Chemistry Modeling of the Oxidation of Highly Oriented Pyrolytic Graphite

Reactive and Inelastic Scattering Dynamics of Hyperthermal O and O2 from a Carbon Fiber Network

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