Spatiotemporal Self-Organization in a Surface Reaction: From the Atomic to the Mesoscopic Scale

Sachs, Christian; Hildebrand, Michael E.; Völkening, Stephan; Wintterlin, Joost; Ertl, G.

doi:10.1126/science.1062883

Cited by 173 publications

(117 citation statements)

References 19 publications

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“…This approach has produced outstanding results in different fields, such as solid-state chemistry or catalysis 21 . The environmental parameters in our simulation chambers, such as temperature, vacuum and gas composition, were as close as possible to the conditions occurring in the CSE.…”

Section: Discussionmentioning

confidence: 99%

“…The potential of surface science methodology to mimic and characterize the essential characteristics of complex problems concerning molecules on surfaces has been previously demonstrated by explaining, among others, the fundamentals of catalysis 21 or the formation of H 2 on the stardust grains 20 . We simulate the conditions of interstellar space using ultra-high vacuum (UHV) chambers equipped with in situ atom-resolved scanning tunnelling microscopy (STM) and third-generation synchrotron radiation-based X-ray photoemission-spectroscopy (XPS), among others.…”

mentioning

confidence: 99%

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Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

et al. 2014

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Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most abundant observed species in interstellar space and are key molecules to understanding the prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here we present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in space. We show that aromatic species can be efficiently formed on the graphitized surface of the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and temperature conditions analogous to those of the interstellar medium. To this aim, we mimic the circumstellar environment using ultra-high vacuum chambers and investigate the SiC surface by in situ advanced characterization techniques combined with first-principles molecular dynamics calculations. These results suggest that top-down routes are crucial to astrochemistry to explain the abundance of organic species and to uncover the origin of unidentified infrared emission features from advanced observations.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

et al. 2014

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“…Alternatively, the chemical patterns could be produced by fabricating domains of catalyst on a surface that promote the production of fuel from reactions in the medium 36. Chemical patterns may have macroscopic to nanoscopic characteristic lengths, allowing systems with a wide range of length scales to be explored 37, 38, 39, 40, 41. When chemically propelled motors operate in such media new phenomena appear; for example, it has been shown that chemically propelled nanomotors can be reflected from traveling chemical fronts in media where cubic autocatalytic reactions take place 42…”

Section: Introductionmentioning

confidence: 99%

Chemically Propelled Motors Navigate Chemical Patterns

Chen

Kapral

2018

Advanced Science

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Very small synthetic motors that use chemical reactions to drive their motion are being studied widely because of their potential applications, which often involve active transport and dynamics on nanoscales. Like biological molecular machines, they must be able to perform their tasks in complex, highly fluctuating environments that can form chemical patterns with diverse structures. Motors in such systems can actively assemble into dynamic clusters and other unique nonequilibrium states. It is shown how chemical patterns with small characteristic dimensions may be utilized to suppress rotational Brownian motions of motors and guide them to move along prescribed paths, properties that can be exploited in applications. In systems with larger pattern length scales, domains can serve as catch basins for motors through chemotactic effects. The resulting collective motor dynamics in such confining domains can be used to explore new aspects of active particle collective dynamics or promote specific types of active self‐assembly. More generally, when chemically self‐propelled motors operate in far‐from‐equilibrium active chemical media the variety of possible phenomena and the scope of their potential applications are substantially increased.

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“…[2] In the past the in situ investigation of catalyst surfaces was difficult, because the most surface sensitive imaging and spectroscopy techniques were restricted to high vacuum conditions. [3,4] Recent instrumental developments however, have made possible the investigations at elevated pressures using imaging [5][6][7][8][9][10] and spectroscopic [11,12,13] methods, among them X-ray photoelectron spectroscopy (XPS) [14,15,16] that has been shown to be able to operate at pressures of up to 10 mbar. [17,18] Here we present the use of XPS at millibar pressures to determine the chemical species near the surface of a catalyst, including the gas phase reaction products, in situ, i.e.…”

Section: Introductionmentioning

confidence: 99%

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Bluhm¹,

Hävecker²,

et al. 2004

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The surface and near-surface region of an active catalyst and the adjacent gas-phase reactants were investigated simultaneously under reaction conditions using in situ X-ray photoelectron spectroscopy (XPS). This investigation of methanol oxidation on a copper catalyst showed that there was a linear correlation between the catalytic activity of the sample and the presence of a sub-surface oxygen species that can only be observed in situ. The concentration profile of the sub-surface oxygen species within the first few nanometers below the surface was determined using photon energy-dependent depth-profiling. The chemical composition of the surface and the near-surface region varied strongly with the oxygen-tomethanol ratio in the reactant stream. The experiments show that the pure metal is not an active catalyst for the methanol oxidation reaction, but that a certain amount of oxygen has to be present in the sub-surface region to activate the catalytic reaction. Oxide formation was found to be detrimental to formaldehyde production. Our results demonstrate also that for an understanding of heterogeneous catalysts a characterization of the surface alone may not be sufficient, and that sub-surface characterization is essential.

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Spatiotemporal Self-Organization in a Surface Reaction: From the Atomic to the Mesoscopic Scale

Cited by 173 publications

References 19 publications

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

Chemically Propelled Motors Navigate Chemical Patterns

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

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