Imaging of spatio-temporal pattern evolution during carbon monoxide oxidation on platinum

Rotermund, Harm Hinrich; Engel, W.; Kordesch, Martin E.; Ertl, G.

doi:10.1038/343355a0

Cited by 273 publications

(109 citation statements)

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“…The loop between this actuation and sensing (both resolved in space and time) through nonintrusive microscopies is then closed through the computer or the experimentalist herself/himself in real time. Our model system is the low-pressure catalytic oxidation of CO on Pt(110), a reaction exhibiting well-documented spatiotemporal patterns [13][14][15][16], and whose macroscopic modeling has reached an advanced level [17][18][19][20].In this Letter we study the interaction of reactive pulses with a single, spatially coherent but temporally mobile heterogeneity. In particular, we use a temperature heterogeneity, localized in space and steadily moving in time, to ''drag'' spontaneously isothermally forming reactive pulses and fronts with speeds differing from their natural speed.…”

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confidence: 99%

Gentle Dragging of Reaction Waves

et al. 2003

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Using a recently realized ''addressable catalyst surface'' [Science 294, 134 (2001)] we study the interaction of chemical reaction waves with prescribed spatiotemporal fields. In particular, we study how a traveling chemical pulse is ''dragged'' by a localized, moving temperature heterogeneity as a function of its intensity and speed. The acceleration and eventual ''detachment'' of the wave from the heterogeneity is also explored through simulation and stability analysis. DOI: 10.1103/PhysRevLett.90.018302 PACS numbers: 82.40.Bj, 05.45.-a, 82.40.Np, 82.45.Jn As the elements of spontaneous pattern formation are progressively understood through theory, experimentation, and scientific computation [1], ways to purposefully interact with the coherent structures (pulses and fronts) that constitute the building blocks of spatiotemporal patterns are becoming the focus of extensive research [2,3]. In particular, the stabilization and control of various patterns [3-9] through local, nonlocal, or global feedback, and pattern formation in media with designed heterogeneities [10 -12] are the source of novel insights for spatiotemporal dynamics.To explore such phenomena, we have recently constructed an ''addressable catalyst'': A focused laser beam, manipulated through computer-controlled mirrors and capable of ''writing'' spatiotemporal temperature heterogeneity patterns on a metal single crystal catalyst. The loop between this actuation and sensing (both resolved in space and time) through nonintrusive microscopies is then closed through the computer or the experimentalist herself/himself in real time. Our model system is the low-pressure catalytic oxidation of CO on Pt(110), a reaction exhibiting well-documented spatiotemporal patterns [13][14][15][16], and whose macroscopic modeling has reached an advanced level [17][18][19][20].In this Letter we study the interaction of reactive pulses with a single, spatially coherent but temporally mobile heterogeneity. In particular, we use a temperature heterogeneity, localized in space and steadily moving in time, to ''drag'' spontaneously isothermally forming reactive pulses and fronts with speeds differing from their natural speed. We examine the shapes acquired by these dragged waves and their limits of stability (that is, the range of dragging speeds for which they can exist). Through computer-aided analysis we examine the nature of the detachment instability, marking the loss of the ability of the heterogeneity to drag a pulse in 1D or 2D. Two possible paths to instability (depending on the linearized spectrum crossing) are detected. We explore the postdetachment transient dynamics and the interactions of a pulse with successive elements of a 1D periodic, constant speed array of identical heterogeneities. The theme of pulse dragging is currently also being explored in a variety of physically relevant Hamiltonian systems, or weakly perturbed dissipative variations thereof (targeted transfer of pulses in optical media or the motion/displacement of harmonic traps or optical l...

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Gentle Dragging of Reaction Waves

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“…Uma grande motivação para tais estudos reside na utilização de análogos químicos como modelos funcionais 5 no estudo de padrões de atividade em sistemas biológi-cos, obviamente, bem mais complexos e menos tratáveis 6 . Exemplos de sistemas físico-químicos, cujas propriedades emergentes vêm sendo estudadas recentemente incluem processos heterogêne-os nas interfaces sólido/gás [7][8][9] e sólido/líquido [10][11][12] , assim como reações homogêneas como no caso dos osciladores da família do bromato [13][14][15][16] .…”

Section: Propriedades Emergentes E Sistemas Complexosunclassified

Dinâmica complexa no sistema bromato/hipofosfito/acetona/manganês e ferroína

Tokoro¹,

Oliveira²,

Varela³

2007

Quím. Nova

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Recebido em 19/12/06; aceito em 10/4/07; publicado na web em 25/10/07 COMPLEX DYNAMICS IN THE BROMATE/HYPOPHOSPHITE/ACETONE/MANGANESE AND FERROIN SYSTEM. New chemical systems have been recently designed for the study of complex phenomena such as oscillatory dynamics in the temporal domain and spatiotemporal pattern formation. Systems derived from oscillators based on the chemistry of bromate are the most extensively studied, with the celebrated Belousov-Zhabotinsky (BZ) reaction being the most popular example. Problems such as the formation of bubbles (CO 2 ) and solid precipitate in the course of the reaction and the occurrence of simply short-lived oscillations under batch conditions are very common and, in some cases, compromise the use of some of these systems. It is investigated in this paper the dynamic behavior of the bromate/hypophosphite/acetone/dual catalyst system, which has been sugested as an interesting alternative to circumvent those inconvenients. In this work, manganese and ferroin are employed as catalysts and the complete system (BrO 3 -/H 2 PO 2 -/acetone/Mn(II)-ferroin) is studied under batch conditions. Temporal symmetry breaking was studied in a reactor under agitation by means of simultaneous records of the potential changes of platinum and Ag/AgBr electrodes, both measured versus a reversible hydrogen electrode. Additionally, spatio-temporal formation of target patterns and spiral waves were obtained when the oscillating mixture was placed in a quasi two-dimensional reactor.Keywords: oscillations; chemical kinetics; pattern formation. INTRODUÇÃO Propriedades emergentes e sistemas complexosDefine-se formalmente comportamento emergente como "comportamento coletivo de um agregado de subunidades fisicamente similares não observado individualmente por nenhuma sub-unidade" 1 . Em um contexto mais amplo, Korn 2 compilou as principais definições de propriedades emergentes como sendo dadas em termos: da não aditividade das suas partes; de uma novidade, algo simplesmente novo; da não dedutibilidade e, da não preditabilidade. Finalmente, o autor 2 encerra que emergência é a nova associação que conduz a novas e estáveis configurações observáveis. Emergência é a propriedade mais importante dos sistemas complexos. O comportamento de um sistema complexo não pode ser entendido em termos apenas da extrapolação das propriedades dos seus componentes individuais, ou seja, as propriedades que surgem no nível macroscópico não podem ser preditas a partir das propriedades dos componentes microscópicos, como apresentado no artigo clássico More is different 3 .Whitesides e Ismagilov 4 classificaram um sistema complexo como um sistema no qual: sua evolução é muito sensível às condições iniciais ou a pequenas perturbações; o número de componentes independentes interagindo é grande ou, um no qual há vários caminhos através dos quais a evolução do sistema pode proceder. Comportamento complexo expresso na forma de cinética oscilatória e estruturação espacial, por exemplo, é comum em muitos sistemas reacionais mantidos...

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“…One clear example is the pioneering work of Jakubith [23] and Rotermund [24] et al on the evolution of spatio-temporal patterns formed on Pt surfaces during the oxidation of carbon monoxide. On Pt surfaces the reaction proceeds via the recombination of CO with O previously formed from the dissociative adsorption of molecular oxygen.…”

Section: Application In Catalysismentioning

confidence: 99%

“…In the past decades, studies regarding the CO oxidation on different substrates using PEEM have been conducted [24,[48][49][50][51]. The nature of the pattern formation under well determined experimental conditions have been the main object of study.…”

Section: Application In Catalysismentioning

confidence: 99%

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

Prieto

Schmidt

2017

Catal Lett

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Catalysis is a hot topic in research with the focus on finding catalysts that show better activity or selectivity on processes on technological or industrial interest. The use of model systems of applicable materials has proven to be a successful approach in the last decades to obtain information on the fundamental properties of these materials, leading eventually to a better understanding how real catalysts work. This knowledge is extremely important in the sense that it allows an optimization of the catalyst composition, thus leading to a rational design of new materials. For these fundamental studies, a variety of probing techniques such as X-ray photo-electron spectroscopy, scanning tunnel microscopy, and temperature programmed desorption have been applied. In this article, we discuss how low energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) can contribute to the fundamental understanding of relevant surface processes taking place on model catalysts. Also, the capability of these techniques on addressing open questions in catalysis is discussed

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Imaging of spatio-temporal pattern evolution during carbon monoxide oxidation on platinum

Cited by 273 publications

References 7 publications

Gentle Dragging of Reaction Waves

Gentle Dragging of Reaction Waves

Dinâmica complexa no sistema bromato/hipofosfito/acetona/manganês e ferroína

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

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