Electronic and optical properties of polyanionic metal clusters

聚阴离子金属簇的电子和光学性质

• 批准号: 439290737
• 负责人: Privatdozent Dr. Josef Tiggesbäumker, Ph.D.
• 金额: --
• 依托单位: AG Cluster und Nanostrukturen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/439290737?language=en
• 关键词: Electronic; optical; properties; polyanionic; metal

The physical and chemical properties of finite systems often scale in a simple way with the particle size and show characteristic trends. In contrast, very small clusters show distinct quantum-size effects when changing the number of atoms. Recently developed experimental methods for generating mass-selected, polyanionic metal clusters in digital radio frequency traps have opened up opportunities to study (metallic) nanosystems on not yet accessible potential surfaces. An exciting aspect is the formation of a repulsive Coulomb potential as a characteristic feature, whereby a barrier is formed by the interplay between charge repulsion and electron-electron correlations. Binding energies above the vacuum level allows for a relaxation of the complex by electron tunneling through the barrier. In contrast to molecules and fullerenes, the photo-induced dynamics of polyanionic systems with delocalized electrons has not been studied in detail by experiment and theory so far. In addition to the electronic structure and possible anisotropies of the Coulomb barrier, the project focuses on the optical activity of polyanionic metal clusters with emphasis on thecollective excitations. Currently, the decay of the plasmon mode and the coupling to single-electron levels in nanoparticles is still under discussion. We will conduct experiments using tunable laser pulses, as well as the pump-probe technique in order to study the physical properties of polyanionic metal clusters, using angular-resolved spectroscopy as an extension of the already existing electrontime-of-flight diagnostics. We aim to characterize the electronic level structure, the optical response and the ultrafast dynamics. Tunneling and internal relaxation are relevant decay pathways, which have to be considered in the photoemission process. In the experiments we concentrate on copper, silver and gold clusters as they represent model systems due to their isoelectronic structure. Due to their plasmonic properties, the noble metal clusters are also interesting for technical applications.

有限系统的物理和化学性质通常以简单的方式随颗粒尺寸变化并显示出特征趋势。相比之下，非常小的团簇在改变原子数量时表现出明显的量子尺寸效应。最近开发的在数字射频陷阱中生成质量选择的聚阴离子金属簇的实验方法为研究尚未可及的潜在表面上的（金属）纳米系统提供了机会。一个令人兴奋的方面是排斥库仑势的形成作为特征，由此电荷排斥和电子-电子相关性之间的相互作用形成势垒。高于真空能级的结合能允许通过电子隧道穿过势垒来弛豫络合物。与分子和富勒烯相比，具有离域电子的聚阴离子系统的光致动力学迄今为止尚未通过实验和理论进行详细研究。除了库仑势垒的电子结构和可能的各向异性之外，该项目还重点研究聚阴离子金属簇的光学活性，重点是集体激发。目前，纳米粒子中等离激元模式的衰变和与单电子能级的耦合仍在讨论中。我们将使用可调谐激光脉冲以及泵浦探针技术进行实验，以研究聚阴离子金属簇的物理性质，并使用角分辨光谱作为现有电子飞行时间诊断的扩展。 我们的目标是表征电子能级结构、光学响应和超快动力学。隧道效应和内部弛豫是相关的衰变路径，在光电子发射过程中必须考虑这些路径。在实验中，我们专注于铜、银和金簇，因为它们由于其等电子结构而代表了模型系统。由于其等离子体特性，贵金属簇在技术应用方面也很有趣。