Probing a gas/liquid acid-base reaction by X-ray photoelectron spectroscopy.
Probing a gas/liquid acid-base reaction by X-ray photoelectron spectroscopy.
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DOI：
10.1002/anie.201304115
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发表时间：
2013-08
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通讯作者：
Inga Niedermaier;N. Taccardi;P. Wasserscheid;F. Maier;H. Steinrück
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文献类型：
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作者：
Inga Niedermaier;N. Taccardi;P. Wasserscheid;F. Maier;H. Steinrück
反应化学中最基本的问题之一是确定反应机理、可能的中间产物或副产物以及反应动力学。许多分析方法经常被用来监测反应的进展和提取关于潜在分子机制的信息。这些方法包括核磁共振、UV/VIS、红外光谱、质谱学和量热技术。X射线光电子能谱(XPS)传统上不用于反应监测，尽管它具有补充这些技术的潜力，甚至在某些方面更具优势。与许多其他光谱工具不同，XPS是定量的，可以直接、原位观察样品中除氢和氦以外的几乎所有元素。化学环境的变化反映在相应的芯层结合能的变化上，也就是所谓的化学位移。此外，XPS对样品表面具有纳米级的典型信息深度敏感。这在研究气相物种与反应表面的非均相反应时特别有用。正是这两种反应物之间的这种界面主要决定了反应行为。在过去的20年里，利用实时XPS或其他表面敏感技术，在理解催化活性金属或金属氧化物表面上的反应方面做出了许多贡献。[1-10]由于这些技术大多需要超高真空(UHV)条件，它们的应用仅限于覆盖有
One of the most fundamental issues in reaction chemistry is the identification of the reaction mechanism, possible intermediates, or by-products and the reaction kinetics. Numerous analytical methods are routinely employed to monitor the progress of reactions and to extract information on the underlying molecular mechanisms. These methods include NMR, UV/Vis, and IR spectroscopy, mass spectrometry, and calorimetric techniques. X-ray photoelectron spectroscopy (XPS) is not traditionally used for reaction monitoring, although it has the potential to complement these techniques and is even superior in certain respects. Unlike many other spectroscopic tools, XPS is quantitative and enables direct, insitu observation of nearly all elements present in a sample, except hydrogen and helium. Changes of the chemical environment are reflected by changes in the corresponding core-level binding energy, the so-called chemical shifts. Furthermore, XPS is sensitive to the sample surface with a typical information depth at the nanometer scale. This is particularly helpful when studying heterogeneous reactions of gas-phase species with reactive surfaces. It is this interface between both reactants which mainly determines the reaction behavior. Thus, the investigation of processes at reactive interfaces is of fundamental importance.Within the last 20 years, many contributions have been made towards the understanding of reactions on catalytically active metal or metal oxide surfaces by using real-time XPS or other surface-sensitive techniques.[1–10] As most of these techniques require ultra-high vacuum (UHV) conditions, their application is restricted to solid surfaces covered with