Surface electronic structure, solvation properties of simple atoms and ions studied by electron spectroscopy and density functional theory

用电子能谱和密度泛函理论研究简单原子和离子的表面电子结构、溶剂化性质

• 批准号: 91656715
• 负责人: Professor Dr. Stefan Krischok
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/91656715?language=en
• 关键词: Surface; electronic; structure; solvation; properties

Detailed knowledge of the surface structure of Ionic Liquids (IL) and the solvation of atoms, molecules and clusters appears indispensable for understanding their properties in order to be able to refine the performance of these materials, in particular as “green solvents”, in e.g. interfacial chemistry and electrochemical applications. Further important aspects are the analysis of impurities, which might be surface active, the interaction with molecules, in particular those present under operation conditions, and their modification due to radiation induced effects or plasma conditions. Related to these aspects, possible degradation caused by these interactions is of high relevance for many applications. For some of the approaches, the solution of metals or semiconductors and their possible surface enrichment are very interesting. Additionally, in case of nanoparticle production from ILs it might be of large importance to analyze the influence of the particular chosen conditions (IL, operating conditions, solvated species) on the formed products.In order to improve our fundamental understanding of the above mentioned topics and to provide detailed information on surface chemistry and electronic structure for our partners, we plan to apply a combination of photoelectron spectroscopies and Metastable Impact Electron Spectroscopy (MIES) with “first principles” calculations possibly accompanied by other experimental methods (mass spectroscopy, ion scattering and vibrational spectroscopy). Due to its extreme surface sensitivity MIES provides information on the rim of the condensed material under study, e.g. the tails of the wavefunctions of species in the very topmost surface layer. As XPS, UPS and MIES are increasingly surface sensitive, the combination of XPS and UPS with MIES is a very powerful tool for gaining detailed information on the surface electronic structure. This holds in particular, if the interpretation of the data is based on reliable theoretical calculations. Moreover, our experimental techniques are complementary to those applied by the group of Prof. Steinrück, which is also studying the surface properties. The existing collaboration with this group will be continued. In order to obtain the desired information about the near surface region, we have set up a working program that is, in addition, strongly interconnected to other research proposals within the SPP. In more detail the following questions will be addressed:• Surface properties of the selected ILs will be studied by combining surface-sensitive experimental methods and “first principles” calculations. In particular the following of ILs are of interest:(i) ILs which serve as model liquids to elucidate fundamental properties of the molecular surface structure of an ionic liquid.(ii) ILs of interest for our partners, which apply them to study the nanoparticle growth by the ILplasma-interaction (Prof. Janek, JLU Gießen and Prof. Endres, TU Clausthal).(iii) ILs containing transition metals from the group of Prof. Sundermeyer, Universität Marburg.For all these ILs we will thoroughly screen them for changes of the IL-ion-orientation at the ILvacuum interface with temperature.• The interaction of atoms, complexes and molecules with ILs will be studied to obtain information about their solvation properties as well as potential surface segregation. These studies include the analysis after in-situ evaporation of atoms onto IL films and the analysis of samples provided by partners.• Changes of ILs under the influence of environmental conditions will be studied to gain important information on degradation effects and mechanisms. In addition photo-induced effects will be considered in order to ensure the reliability of our data and to obtain information on photo-stimulated degradation.• Metal and semiconductor particles provided by our partners will be analyzed in particular with respect to the chemical composition in order to obtain important information on their properties and possibilities of further tuning their properties.

离子液体（IL）的表面结构和原子、分子和团簇的溶剂化的详细知识对于理解它们的性质是必不可少的，以便能够改进这些材料的性能，特别是作为“绿色溶剂”，例如界面化学和电化学应用。进一步重要的方面是杂质的分析，这些杂质可能具有表面活性，与分子的相互作用，特别是在操作条件下存在的分子，以及由于辐射诱导效应或等离子体条件而引起的修饰。与这些方面相关的是，由这些交互引起的可能的降级与许多应用程序高度相关。对于其中一些方法，金属或半导体的溶液及其可能的表面富集是非常有趣的。此外，在从IL生产纳米颗粒的情况下，分析特定选择的条件（IL，操作条件，溶剂化物质）对形成产物的影响可能非常重要。为了提高我们对上述主题的基本理解，并为我们的合作伙伴提供有关表面化学和电子结构的详细信息，我们计划将光电子能谱和亚稳态冲击电子能谱（MIES）结合“第一性原理”计算，可能伴有其他实验方法（质谱，离子散射和振动谱）。由于其极高的表面灵敏度，密斯提供了所研究的凝聚态材料边缘的信息，例如，最上层表面层中物质的波函数的尾部。由于XPS、UPS和密斯对表面的敏感性越来越高，因此XPS、UPS与密斯的结合是获得表面电子结构详细信息的有力工具。如果对数据的解释是基于可靠的理论计算，这一点尤其成立。此外，我们的实验技术与steinr<e:1> ck教授小组所应用的实验技术是互补的，后者也在研究表面性质。与该小组的现有合作将继续进行。为了获得有关近表面区域的所需信息，我们建立了一个工作计划，此外，该计划与SPP内的其他研究计划密切相关。更详细地说，将解决以下问题：•将通过结合表面敏感实验方法和“第一性原理”计算来研究所选ILs的表面性质。特别值得注意的是：(i)离子液体的分子表面结构作为模型液体来阐明离子液体分子表面结构的基本性质。（ii）我们的合作伙伴感兴趣的il，将它们应用于通过il等离子体相互作用研究纳米粒子的生长（Janek教授，JLU Gießen和Endres教授，TU Clausthal）。（三）含过渡金属的il，来自Sundermeyer教授，Universität Marburg的研究小组。对于所有这些il，我们将彻底筛选它们在il真空界面上的il离子取向随温度的变化。•原子，配合物和分子与ILs的相互作用将被研究，以获得有关其溶剂化性质以及潜在表面偏析的信息。这些研究包括原子在IL薄膜上原位蒸发后的分析和对合作伙伴提供的样品的分析。•研究环境条件下il的变化，获得降解效果和机制的重要信息。此外，为了确保我们的数据的可靠性和获得光刺激降解的信息，将考虑光诱导效应。•我们将对合作伙伴提供的金属和半导体颗粒进行化学成分分析，以获得有关其性质和进一步调整其性质的可能性的重要信息。