Laser- and Detectionsystem for transient absorption spectroscopy with two excitation pulses

所提出的光谱可调谐的飞秒激光系统和用于时间分辨瞬时吸收光谱的探测系统，可选择使用第二个激发脉冲，从而能够以飞秒时间分辨率表征光活性系统中的超快光驱动过程。拟议的装置将加强皇家警察部队凯泽斯劳滕-朗道研究光、自旋和物质相互作用的战略研究领域，具体涉及光学和材料科学中心内莱茵兰-帕拉特纳州研究倡议的侧面区域。在化学系申请者工作组计划的项目中，将使用拟议的设备，重点是研究用于光驱动氧化还原催化的材料中的光诱导过程，例如通过还原水产生氢。利用计划中的激光和探测系统，将研究胶体半导体纳米结构(例如量子点和纳米棒)中的基本光驱动过程，如激子弛豫过程、载流子局域化和复合过程，以及基于这些纳米结构的杂化材料组件之间的能量和电荷载流子转移。这项工作的总体目标是了解导致期望功能的基本机制，并利用所获得的知识基于导出的结构-动力学-功能关系来改进系统。使用多个激发脉冲的选择将使从新的角度研究涉及多个电荷载流子的特定过程成为可能。几个电荷载流子的转移需要通过连续的激发/电荷转移序列逐步地连续电荷转移，或者同时产生几个电荷载流子并将它们准同时转移到合适的反应中心。这些场景将在基于胶体半导体纳米结构的光活性杂化材料中用所提出的系统进行研究。此外，该激光系统还将能够通过瞬时吸收光谱研究功能过渡金属化合物中的超快分子过程，如电荷、能量和自旋转移，并通过观察碎裂动力学来研究气相中的超快分子过程。

The proposed spectrally tunable femtosecond laser system and detection system for time-resolved transient absorption spectroscopy with the optional use of a second excitation pulse will enable the time-resolved characterization with fs time resolution of ultrafast light-driven processes in photoactive systems. The proposed device will strengthen the strategic research field of the RPTU Kaiserslautern-Landau for investigating the interaction of light, spin and matter, specifically addressed in the profile area of the Research Initiative of the Federal State of Rhineland-Palatinate within the Center for Optics and Materials Sciences (OPTIMAS). One focus of the planned projects in the applicants working groups in the Department of Chemistry, in which the proposed device will be used, is the investigation of light-induced processes in materials for light-driven redox catalysis, e.g. the generation of hydrogen by reducing water. With the planned laser and detection system, the fundamental light-driven processes in colloidal semiconductor nanostructures, e.g. quantum dots and nanorods, such as exciton relaxation processes, charge carrier localization and recombination, and energy and charge carrier transfer between the components of hybrid materials based on these nanostructures will be investigated. The general goal of the work is to understand the basic mechanisms that lead to a desired function and to use the knowledge gained to improve the systems based on the derived structure-dynamics-function relationships. The option of using multiple excitation pulses will make it possible to study specific processes involving multiple charge carriers from a new perspective. The transfer of several charge carriers requires either a step-by-step consecutive charge transfer through successive excitation/charge transfer sequences or a simultaneous generation of several charge carriers and their quasi-simultaneous transfer to a suitable reaction center. These scenarios are to be investigated in photoactive hybrid materials based on colloidal semiconductor nanostructures with the proposed system. In addition, the laser system will enable the investigation of ultrafast molecular processes such as charge, energy, and spin transfer in functional transition metal compounds in both, the condensed phase by transient absorption spectroscopy and in the gas phase by observing fragmentation dynamics.