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  • 1
    Electronic Resource
    Electronic Resource
    Kinetic oscillations in the catalytic CO oxidation on Pt(100): Periodic perturbations (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 742-749 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Periodic modulations of oxygen pressure or temperature were applied in the catalytic oxidation of CO on a Pt(100) surface under isothermal, low pressure conditions. Transitions from aperiodic autonomous oscillations to regular phase-locked behavior could be observed. Computer simulations using a stochastic cellular automaton model yielded qualitatively similar results. The spatial distribution in both experiment and simulation varies essentially in phase over the whole surface area under the influence of the periodic perturbation, while wave propagation in the autonomous system causes more irregular overall behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453572
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetic oscillations in the catalytic CO oxidation on Pt(100): Computer simulations (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5328-5336 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The previously observed phenomena of temporal and spatial self-organization during the catalytic oxidation of CO on a Pt(100) surface were computer simulated by use of the cellular automaton technique. The underlying model is footed on the knowledge about the individual reaction steps (adsorption, desorption, surface structural transformation, etc.), which in turn formed the basis of a previous theoretical treatment in terms of the formulation and solution of a set of coupled differential equations. The present result nicely show the formation and propagation of two-dimensional patterns, and they reproduce qualitatively well all the experimental observations. The development of macroscopic patterns even with an a priori perfectly homogeneous surface is a particularly interesting effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451676
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanisms of spatial self-organization in isothermal kinetic oscillations during the catalytic CO oxidation on Pt single crystal surfaces (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 510-521 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rate of catalytic CO oxidation on Pt(100) and (110) surfaces at low pressures (≤10−4 Torr) and under isothermal conditions may exhibit sustained temporal oscillations which are coupled with periodic transformations of the surface structures between reconstructed and nonreconstructed phases, the latter exhibiting higher oxygen sticking coefficients and hence higher reactivity. With Pt(100) the two surface phases exhibit a much larger difference in reactivity (=oxygen sticking coefficient) than with Pt(110), which effect accounts for the qualitative differences in the oscillatory behavior: if two of the control parameters (say pO2, T) are kept fixed, the third (pCO) may be varied with Pt(100) over a fairly wide range without leaving the oscillatory region. Minor (〈1%) fluctuations of the partial pressures associated with the varying reaction rate are hence without any noticeable effect. Coupling between surface reaction and diffusion causes wave propagation of the surface phase transformations and therefore spatial self-organization, as demonstrated by scanning LEED experiments. With Pt(110), on the other hand, the oscillatory region is very narrow. In this case mass transport through the gas phase as caused by the small pressure variations associated with the reaction lead to synchronization between different parts of the surface. Computer simulations with the cellular automaton technique confirm qualitatively the experimental findings and support the conclusions reached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456501
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  • 4
    Electronic Resource
    Electronic Resource
    Dispersion relation and spiral rotation in an excitable surface reaction
    Amsterdam : Elsevier
    Physica A: Statistical Mechanics and its Applications 188 (1992), S. 78-88 
    Details
    ISSN: 0378-4371
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-4371(92)90255-O
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  • 5
    Electronic Resource
    Electronic Resource
    Structural effects on the dynamics of an electrocatalytic oscillator
    Amsterdam : Elsevier
    Chemical Physics Letters 192 (1992), S. 254-258 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(92)85461-I
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  • 6
    Electronic Resource
    Electronic Resource
    Hyperchaos in a chemical reaction
    Amsterdam : Elsevier
    Chemical Physics Letters 193 (1992), S. 305-310 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(92)85672-W
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  • 7
    Electronic Resource
    Electronic Resource
    Spiral waves in a surface reaction: Model calculations (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 1202-1214 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A systematic study of spiral waves in a realistic reaction-diffusion model describing the isothermal CO oxidation on Pt(110) is carried out. Spirals exist under oscillatory, excitable, and bistable (doubly metastable) conditions. In the excitable region, two separate meandering transitions occur, both when the time scales become strongly different and when they become comparable. By the assumption of surface defects of the order of 10 μm, to which the spirals can be pinned, the continuous distribution of wavelengths observed experimentally can be explained. An external periodic perturbation generally causes a meandering motion of a free spiral, while a straight drift results, if the period of the perturbation divided by the rotation period is a natural number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466650
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  • 8
    Electronic Resource
    Electronic Resource
    Theoretical modeling of spatiotemporal self-organization in a surface catalyzed reaction exhibiting bistable kinetics (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 8595-8604 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A two-variable Langmuir–Hinshelwood mechanism for isothermal CO oxidation on a catalytically active surface is presented. It shows bistability stemming from 2 cusp bifurcations, which can be obtained analytically for low pressure. Inclusion of CO diffusion on the surface leads to a system of partial differential equations, which exhibits nucleation and front propagation phenomena in the bistable region. While the line of equistability could with good accuracy be solved for analytically, the front velocities and critical radii for nucleation had to be determined numerically (using the method of heteroclinic orbits). Throughout the calculations the kinetics and rate constants for the CO oxidation on Pt(111) are used. Here the model can be reduced by adiabatic elimination of one variable (namely oxygen coverage) allowing a comparison to the exactly solved one-variable Schlögl model. Possible implications for future experimental work are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462312
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  • 9
    Electronic Resource
    Electronic Resource
    Current Oscillations in the Electrochemical Oxidation of Formic Acid at Pt Single Crystal Surfaces (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 7613-7618 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100082a036
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  • 10
    Electronic Resource
    Electronic Resource
    Oscillatory instabilities during formic acid oxidation on Pt(100), Pt(110) and Pt(111) under potentiostatic control. I. Experimental (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 979-990 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The experimental characterization of the current/outer potential (I/U) behavior during the electrochemical CO oxidation on Pt(100), Pt(110) and Pt(111) is used as the first step towards a thorough investigation of the processes occurring during the electrochemical formic acid oxidation. The CO study is followed by new cyclovoltammetric results during the electrochemical formic acid oxidation on the corresponding Pt single crystals. At high concentrations of formic acid, the cyclovoltammograms revealed a splitting of the large current peak observed on the cathodic sweep into two peaks whose dependence on scan rate and reverse potential was investigated. It turned out that the presence of a sufficiently large ohmic resistance R was crucial for oscillatory instabilities. Given an appropriate resistance, all three Pt surfaces were found to exhibit current oscillations at both low and high formic acid concentrations. On Pt(100) stable mixed-mode oscillations were observed. In addition, the sensitivity of the oscillations to stirring was investigated. Whereas the period-1 oscillations were found to be independent of stirring, the mixed-mode oscillations transformed into simple oscillations with stirring. The mechanism giving rise to instability and oscillations is described. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474450
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