Highly sensitive infrared studies on supported metal cluster adsorbates by infrared cavity ringdown spectroscopy

通过红外腔衰荡光谱对负载型金属簇吸附物进行高灵敏度红外研究

• 批准号: 21748643
• 负责人: Professor Dr. Ulrich Heiz
• 金额: --
• 依托单位: Lehrstuhl für Physikalische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/21748643?language=en
• 关键词: Highly; sensitive; infrared; studies; supported

This project aims to develop a highly sensitive infrared spectroscopic technique, the infrared cavity ringdown spectroscopy (IR-CRDS), for studying reactants, intermediates and product molecules adsorbed on size-selected, supported metal clusters. Vibrational fingerprints will not only allow for identification of the adsorbents and reaction mechanisms on clusters, but vibrational shifts with respect to the gas phase, as a function of cluster size and measured for various types of cluster¿s trapping centers are of fundamental interest for elucidating the bonding mechanism of the adsorbents to the clusters. CRDS is extremely sensitive allowing the detection of weak optical transitions (¿= 0.1 Å2) for cluster coverages as low as 1010 /cm2 (~10-5 monolayer, ML). This is the first time this method will be used to study chemical processes on surfaces. Its extreme sensitivity will allow to extend infrared studies for the characterization of C-H bonds, which is difficult to perform by using conventional techniques. Such studies will open up the possibility to investigate in detail the chemistry of small clusters in the non-scalable size regime with respect to hydrocarbons. We plan to study e.g. the activation of methane, the hydrogenation of aliphatic or aromatic hydrocarbons, the selective dehydrogenation of alkenes, or the possible reaction mechanisms of the polymerization of acetylene on small metal clusters.

该项目旨在开发一种高度敏感的红外光谱技术，即红外腔度环光谱（IR-CRDS），用于研究反应物，中间体和产品分子，这些分子吸附在尺寸选择的，支持的金属簇上。振动的指纹不仅将允许识别簇上的吸附剂和反应机制，而且还可以鉴定相对于气相的振动转移，这是集群大小的函数，并针对各种类型的群集捕获中心进行了衡量，这是阐明对焦点的粘结机制的基本兴趣。 CRD非常敏感，允许检测弱的光学转变（=0.1Å2），以低至1010 /cm2的群集覆盖率（〜10-5单层，ML）。这是该方法首次用于研究表面上的化学过程。它的极端敏感性将允许扩展红外研究以表征C-H键，这很难使用常规技术。此类研究将开辟详细研究在不可缩小尺寸方案中相对于碳氢化合物的小簇的化学。我们计划学习，例如甲烷的激活，脂肪族或芳香族烃的氢化，烷烃的选择性脱氢作用或乙炔在小金属簇上聚合的可能反应机制。