Elias Diesen , Mehmet Ugur Coskun , Sergio Díaz-Coello , Vanessa J. Bukas , Julia Kunze-Liebhäuser , Karsten Reuter
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引用次数: 0
Abstract
We employ infrared reflection absorption spectroscopy (IRRAS) and first-principles density-functional theory (DFT) to revisit the reported “anomalous” negative Stark shift of the CO stretch frequency at Pt(111) in aqueous electrolyte. Our comprehensive IRRAS measurements confirm the existence of a potential region with negative Stark shift around 0.5 V vs. the reversible hydrogen electrode, but only at a sufficiently high CO concentration in the electrolyte. As these are exactly the same conditions for the occurrence of a phase transition from a -3CO to a R23.4-13CO adsorbate structure, we explicitly compute the Stark shift for these two phases using DFT. Neither phase exhibits a negative Stark shift, but the absolute stretch frequencies of the atop CO in the two structures are slightly shifted with respect to each other. Remeasuring IRRAS with high resolution indeed reveals a doublet character of the absorption band in the potential region corresponding to the negative Stark shift. Separate fits of the two components then yield positive Stark shifts in quantitative agreement with the calculated values. The “anomalous” negative Stark shift simply arises from effectively fitting one component to a doublet spectral feature in a potential range with phase coexistence at the surface.
期刊介绍:
Surface Science is devoted to elucidating the fundamental aspects of chemistry and physics occurring at a wide range of surfaces and interfaces and to disseminating this knowledge fast. The journal welcomes a broad spectrum of topics, including but not limited to:
• model systems (e.g. in Ultra High Vacuum) under well-controlled reactive conditions
• nanoscale science and engineering, including manipulation of matter at the atomic/molecular scale and assembly phenomena
• reactivity of surfaces as related to various applied areas including heterogeneous catalysis, chemistry at electrified interfaces, and semiconductors functionalization
• phenomena at interfaces relevant to energy storage and conversion, and fuels production and utilization
• surface reactivity for environmental protection and pollution remediation
• interactions at surfaces of soft matter, including polymers and biomaterials.
Both experimental and theoretical work, including modeling, is within the scope of the journal. Work published in Surface Science reaches a wide readership, from chemistry and physics to biology and materials science and engineering, providing an excellent forum for cross-fertilization of ideas and broad dissemination of scientific discoveries.