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  • 1
    Electronic Resource
    Electronic Resource
    Dynamic response of an irreversible catalytic reaction to periodic variation of the reactant's pressure (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 3890-3896 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dynamic response of the Ziff, Gulari, and Barshad model for the catalytic oxidation of CO, to a periodic variation of the external pressure is studied close to the CO-poisoning transition. Due to the applied pressure, a considerable enhancement in the catalytic activity is observed when the system is briefly driven into the CO-poisoned state. However, saturation of catalysts' surface can be induced by applying signals of either long period or high amplitude. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480931
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of long-range interactions in the diffusion of multiparticle systems (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 5581-5587 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The diffusion of multiparticle systems with long-range dipolar repulsion and long-range dipolar repulsion perturbed by randomly distributed dipolar impurities is studied by means of computer simulations. Our investigation is motivated by experimental studies of the diffusion of alkali atoms on clean and contaminated (e.g. by oxygen atoms) single crystal metal and semiconductor surfaces. Concentration profiles of the diffusion fronts are in qualitative agreement with the experimental findings. Comparing to the behavior of non-interacting particles, it is found that dipolar repulsion considerably enhance the chemical diffusion coefficient, particularly at lower coverages where a sharp peak is observed close to θ(approximate)0.09. In contrast, the chemical diffusion coefficient of non-interacting particles exhibits a smooth maximum close to θ(similar, equals)0.5. The presence of random dipolar impurities causes a delay of the diffusion process and the low coverage peak of the diffusion coefficient becomes shifted to θ(approximate)0.16 . The number of distinct sites visited by the diffusing particles, which is relevant for the evaluation of the rate constant for diffusion-limited reactions, is also studied and the results are compared with those of non-interacting particles. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475947
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  • 3
    Electronic Resource
    Electronic Resource
    Edge effects on the random sequential adsorption of hot dimers (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 5378-5380 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Both jamming coverage and percolating probability profiles are studied for the random sequential adsorption of hot dimers in two dimensions. Jamming profiles show that the effect of the sample edge dies off after a few lattice spaces. On the contrary, in percolating profiles the effect propagates into the bulk
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467152
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  • 4
    Electronic Resource
    Electronic Resource
    Shift of first-order phase transitions in thin films due to boundary fields: A computer simulation (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3700-3706 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first-order phase transition of the ferromagnetic Ising model driven by the magnetic field at temperatures below criticality is studied by Monte Carlo methods for a two-dimensional thin film geometry, L×M with two free boundaries of length M(very-much-greater-than)L, at which boundary fields act. This model study is relevant, in particular, for phase transitions in monolayers adsorbed at stepped surfaces. While in the bulk geometry (L→∞) this transition occurs for zero field in the present model, with the system "jumping'' from a state with uniformly positive magnetization to a state with uniformly negative magnetization, in the thin film geometry the transition occurs at a critical field H*∼L−1, and the two states between which the transition occurs are characterized by strongly nonuniform magnetization profiles across the film. These findings are in agreement with the scaling theory of Fisher and Nakanishi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456851
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  • 5
    Electronic Resource
    Electronic Resource
    The influence of lateral interactions on the critical behavior of a dimer–monomer surface reaction model (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 9440-9446 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ZGB model [Ziff et al., Phys. Rev. Lett. 56, 2553 (1986)] for a monomer–dimer surface reaction process of the type A+(1/2)B2→AB, exhibits two irreversible phase transitions (IPT) from a stationary regime with AB production for p1A≤pA≤p2A, to poisoned states with B (A)-species for pA≤p1A (pA≥p2A), respectively, where pA is the mole fraction of A-species in the gas phase and piA (i=1, 2) are critical points. A generalization of the ZGB model in order to account for both attractive and repulsive interactions between the reactants is presented and discussed. It is found that in most cases the first order IPT at p2A becomes of second order and the critical points are shifted. For some particular choices of the interactions energies it is found that the second order IPT at p1A becomes of first order. Also, a first order IPT from the reactive state to a effectively poisoned regime where A-species are adsorbed forming a c(2×2) metastable structure is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463319
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature-programmed reactions with anomalous diffusion (1988)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 92 (1988), S. 3594-3597 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100323a054
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  • 7
    Electronic Resource
    Electronic Resource
    Study of recombination reactions of particles adsorbed on fractal and multifractal substrata (1988)
    Springer
    Applied physics 47 (1988), S. 399-407 
    Details
    ISSN: 1432-0630
    Keywords: 82.65J ; 66.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Recombination reactions of adsorbed particles on fractal and multifractal media are discussed within the framework of the random walk arguments. Theoretical results, which predict anomalous reaction orderX〉2 in the low coverage regime, are checked by means of Monte Carlo simulations on two-dimensional structures and good agreement is found. Thermal desorption experiments on rough surfaces are simulated by studying temperature programmed reactions on fractal percolating clusters. For this case the simulations giveX≅2.5, i. e. the fractal reaction order is greater than the classical one (X=2). The influence of chemisorbed impurities (poison) on the recombination reaction is also studied and the reaction order is found to increase beyondX=2.5 when increasing the concentration of poison. Isothermal (recombination) desorption from energetically heterogeneous surfaces is simulated on two-dimensional substrata with multifractal distributions of activation energy of diffusion. For this caseX (withX〉2) depends on the energetic heterogeneity of the substrata (X=2 for an homogeneous substratum). The obtained results point out that the fractal chemical kinetic behaviour is not only restricted to the low concentration regime, but it also covers the medium coverage regime, i.e. it holds for a monolayer surface coverageθ≦0.4 in fractal percolating clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615505
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  • 8
    Electronic Resource
    Electronic Resource
    Study of recombination reactions of particles adsorbed on fractal and multifractal substrata (1988)
    Springer
    Applied physics 47 (1988), S. 399-407 
    Details
    ISSN: 1432-0630
    Keywords: 82.65J ; 66.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Recombination reactions of adsorbed particles on fractal and multifractal media are discussed within the framework of the random walk arguments. Theoretical results, which predict anomalous reaction orderX〉2 in the low coverage regime, are checked by means of Monte Carlo simulations on two-dimensional structures and good agreement is found. Thermal desorption experiments on rough surfaces are simulated by studying temperature programmed reactions on fractal percolating clusters. For this case the simulations giveX≅2.5, i. e. the fractal reaction order is greater than the classical one (X=2). The influence of chemisorbed impurities (poison) on the recombination reaction is also studied and the reaction order is found to increase beyondX=2.5 when increasing the concentration of poison. Isothermal (recombination) desorption from energetically heterogeneous surfaces is simulated on two-dimensional substrata with multifractal distributions of activation energy of diffusion. For this caseX (withX〉2) depends on the energetic heterogeneity of the substrata (X=2 for an homogeneous substratum). The obtained results point out that the fractal chemical kinetic behaviour is not only restricted to the low concentration regime, but it also covers the medium coverage regime, i.e. it holds for a monolayer surface coverageθ≦0.4 in fractal percolating clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615505
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  • 9
    Electronic Resource
    Electronic Resource
    Monte Carlo simulation of a bimolecular reaction of the type A+(1/2)B 2 → AB — The influence of A-desorption on kinetic phase transitions (1992)
    Springer
    Applied physics 55 (1992), S. 226-230 
    Details
    ISSN: 1432-0630
    Keywords: 82.65J ; 82.20 ; 68.35R
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The model recently proposed by Ziff et al. [1] for reactions of the type A+(1/2)B 2 → AB is extended in order to study the effect of A-desorption on irreversible (kinetic) phase transitions (IPT). The IPT from a stationary state with AB-production to a B-poisoned state is not influenced by A-desorption. On the other hand, desorption of A-species prevents the existence of a truly A-poinsoned state. Therefore the IPT from the stationary regime to an A-poisoned state does not occur but an apparent phase transition is observed for small values of the desorption probability (P D). The rate of AB-production (R AB ) crosses over from a regime where it becomes dominated by the rate of A-adsorption, when the coverage with A-species is negligible to another regime where R AB is dominated by the rate of B 2-adsorption, when the coverage with B-species is negligible. Within the former regime, R AB decays exponentially with the mole fraction of A-molecules in the gas phase and exhibits a power law dependence with P D (exponent γ=2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334228
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of the “hot”-dimer adsorption mechanism on the kinetics of a monomer-dimer surface reaction (1993)
    Springer
    Applied physics 57 (1993), S. 291-298 
    Details
    ISSN: 1432-0630
    Keywords: 82.20.—w ; 82.65.Jv ; 68.10.Jy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract “Hot” dimers are molecules which after adsorption dissociate and each of the remaining “hot” monomers fly apart up to a maximum distance R from the original adsorption site. The influence of the “hot”-dimer adsorption mechanism on relevant aspects of the bimolecular catalyzed reaction of the type A − (1/2)B 2(“hot”) → AB is studied by means of the Monte-Carlo simulation technique. The temporal evolution of both the reactant's coverages as well as the rate of AB-production is evaluated and discussed. Due to the enhanced probability of “hot” species for encounters with other adsorbed particles, the rate of AB-production becomes faster when increasing R. This behavior may be relevant in the dynamic of some catalyzed reactions such as for example the oxidation of carbon monoxide on transition metal surfaces, i.e. A≡CO, B 2≡O2, and AB≡CO2. Also the sticking coefficient of “hot” dimers and the average distance traveled by the “hot” monomers are evaluated and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332605
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