The first layers of the Metal-Solution interface: interactions of enantioselective modifier and reactant molecules on a wet model catalyst surface

对表面或界面现象的微观理解，如界面上的非均相催化或交换过程，需要有关所研究表面的化学成分和分子排列的实验数据。一般来说，基于电子的光发射光谱，如x射线光电子能谱（XPS）或近边缘x射线吸收精细结构（NEXAFS）光谱，最能提供表面特异性信息。然而，当这些系统要在毫巴或更高的实际压力环境下进行研究时，使电子成为理想表面探针的特性，即它们在物质中的穿透深度短，就成了一个大问题。电子的平均自由程只有毫米或更小的数量级，传统的电子能量分析仪不能再使用了。通常在高反应物压力下甚至在溶液中发生的传统电子能谱和实际催化反应之间的所谓压力间隙，在一定程度上可以通过环境压力电子分析仪来弥补。这种仪器最近才在美国伯克利和德国柏林的同步加速器辐射设施中可用。申请人正在寻求资助前往伯克利ALS进行环境压力光发射实验，研究通常在溶液中发生的局部对映选择性反应的反应物和修饰剂分子的吸附行为。该设备将允许在实际条件下研究反应系统，即在溶剂，水存在的情况下，在催化剂表面接近反应温度。这是传统仪器无法做到的，这就是为什么我们对这种系统中反应物和溶剂分子之间的相互作用知之甚少的原因。然而，更好地了解这种相互作用对于改进溶液中反应的催化剂至关重要。这些测量将是这类的第一次，因此可能对更好地理解溶液中的多相催化有重大影响。

A microscopic understanding of surface or interface phenomena, such as heterogeneous catalysis or exchange processes at interfaces requires experimental data about the chemical composition and molecular arrangement at the surfaces under investigation. In general, surface-specific information is best provided by electron-based photoemission spectroscopy such as X-ray photoelectron spectroscopy (XPS) or near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The property, however, that makes electrons ideal surface probes, namely their short penetration depth in matter, turns out to be a big problem when these systems are to be studied under realistic pressure environments in the range of millibar or higher. The mean free path of electrons is then only of the order of millimetres or less and conventional electron energy analysers cannot be used anymore.This so-called pressure gap between conventional electron spectroscopy and actual catalytic reactions, which usually take place at high reactant pressures or even in solution, is bridged to some extent by ambient pressure electron analysers . Such instruments have become available very recently at synchrotron radiation facilities in Berkeley, USA, and Berlin, Germany.The applicant is seeking funding for travelling to ALS in Berkeley in order to perform ambient pressure photoemission experiments studying the adsorption behaviour of reactants and modifier molecules of a topical enantioselective reaction, which normally takes place in solution. This facility will allow studying the reaction system under realistic conditions, i.e. in the presence of the solvent, water, at the catalyst surface near reaction temperatures. This is impossible with conventional instruments, which is the reason why very little is known about the interplay between reactants and solvent molecules for systems like this. A better understanding of this interaction is, however, crucial for improving catalysts for reactions in solution. These measurements will be the first of this kind and could, therefore, have significant impact on a better understanding of heterogeneous catalysis in solution.