Photoelectron and photoion imaging spectroscopy of metal-doped nanodroplets and rare gas clusters

该项目的目标是研究超冷氦纳米液滴和稀有气体团簇上单个金属原子激发态的能量学和动力学。这些概念上简单的基准系统建立了气相量子动力学和凝聚相量子物理学之间的联系。取决于溶质原子的激发水平，对主机集群的性质，并在客人和主机之间的耦合强度丰富的光谱的动力学现象是由激光激发，在不同的时间尺度上进行。这些过程包括光诱导脱附、部分或完全溶剂化、团簇诱导弛豫、络合物形成以及整个团簇的不寻常Rydberg态的形成。在光谱和时间分辨相结合的研究中，我们的目标是解开各种基本过程，确定它们的动力学和运动学，并根据宾主耦合的程度及其光物理反应的性质对系统进行分类。由氦溶剂的量子性质引起的特定动力学效应将被确定。利用速度图成像（VMI）技术获得了角分辨光电子和光离子谱，并与可调谐窄带纳秒激光和飞秒激光相结合实现了泵浦探测光电离。双色共振电离将允许执行ZEKE和MATI光谱的金属原子簇络合物的激发态，其分辨率仅受激光带宽（~ 0.1 cm-1）的限制。这些研究将对金属在表面和凝聚相环境中的光动力学和光化学产生影响。

The goal of this project is to study the energetics and dynamics of excited states of single metal atoms attached to ultracold helium nanodroplets and to rare gas clusters. These conceptionally simple benchmark systems establish the link between gas-phase quantum dynamics and condensed-phase photophysics. Depending on the level of excitation of the solute atom, on the nature of the host cluster, and on the coupling strength between guest and host a rich spectrum of dynamical phenomena is initiated by laser excitation that proceed on different time scales. These processes include photo-induced desorption, partial or complete solvation, cluster-induced relaxation, complex formation, as well as the formation of unusual Rydberg states of the whole cluster.In a combined spectroscopic and time-resolved study we aim at disentangling various elementary processes, at determining their dynamics and kinematics, and at classifying the systems according to the degree of guest-host coupling and to the nature of their photophysical response. Specific dynamical effects induced by the quantum nature of the helium solvent will by identified. The velocity-map imaging (VMI) technique is applied to obtaining angle-resolved photoelectron and photoion spectra and combined with tunable narrowband nanosecond lasers and femtosecond lasers for pump-probe photoionization. Two-color resonant ionization will allow to perform ZEKE and MATI spectroscopy of excited states of metal atom-cluster complexes that are limited in resolution only by the bandwidth of the laser (~ 0.1 cm-1). These studies will have implications for the photodynamics and photochemistry of metals at surfaces and in condensed phase environments.