Time-resolved photoemission from mass-selected metal clusters and their complexes with biomolecules at insulating surfaces

质量选择的金属簇及其与绝缘表面生物分子的复合物的时间分辨光电发射

• 批准号: 5405993
• 负责人: Professor Dr. Thorsten M. Bernhardt
• 金额: --
• 依托单位: Institut für Oberflächenchemie und Katalyse
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5405993?language=en
• 关键词: Time; resolved; photoemission; mass; selected

Adding or removing one atom changes the physical and chemical properties of small metal clusters drastically. This is particularly true for small silver clusters with up to about 20 atoms. Especially the optical properties of supported and free atomic clusters of silver are intriguing and a strong current interest in this particular cluster system is due to two recent observations: (i) Irradiation of silver oxide particles leads to the photo-induced formation of stable distributions of surface-supported atomic silver clusters; (ii) a strong visible fluorescence was recently found, originating from unprecedented long-lived excited molecular states in atomic silver clusters. These properties uniquely qualify the small atomic silver clusters as a basis for advanced high-density optical storage (via (i)) and read-out (via (ii)) devices. However, neither the detailed electronic origin and cluster size dependence of the observed fluorescence is known up to now, nor any experimental data about the mechanism of the photoreductive formation of silver clusters. In order to get an insight into these fascinating properties of atomic silver clusters, we intend to apply the technique of time-resolved photoemission spectroscopy to a well-defined cluster-support system consisting of mass-selected silver clusters soft-landed onto an atomically flat insulating thin film of magnesia. The goal is to determine the electronic level structure of the supported silver clusters as a function of cluster size as well as the corresponding excited state lifetimes, in order to identify possible radiative and non-radiative transitions.

添加或去除一个原子会大大改变小金属簇的物理和化学性质。这对于最多约20个原子的小银团簇尤其如此。特别是支撑和自由的银原子团簇的光学性质是令人感兴趣的，并且对这种特殊的团簇系统的强烈兴趣是由于最近的两个观察：（i）辐照银氧化物颗粒导致光诱导形成稳定分布的表面支撑的原子银团簇;（ii）最近发现了强烈的可见荧光，起源于原子银团簇中前所未有的长寿命激发分子态。这些性质独特地使小原子银团簇有资格作为先进的高密度光存储（via（i））和读出（via（ii））设备的基础。然而，无论是详细的电子起源和集群大小的依赖性所观察到的荧光是已知的，到现在为止，也没有任何实验数据的光还原形成的银集群的机制。为了深入了解原子银团簇的这些迷人的特性，我们打算应用时间分辨光电子能谱技术的质量选择银团簇软着陆到原子级平坦的绝缘薄膜氧化镁组成的一个定义良好的集群支持系统。我们的目标是确定的支持银团簇的电子能级结构作为簇的大小以及相应的激发态寿命的函数，以确定可能的辐射和非辐射跃迁。