Measurement system for time-resolved optical spectroscopy

有机半导体小组致力于理解发光材料的基本过程，特别是关于设备效率的限制。我们在这一领域最重要的成就之一是发现许多有机染料用作主客系统中的发光体，其光学跃迁偶极矩的取向分布是非各向同性的。这些和相关的问题是当前和计划中的未来研究项目的主题。在这种情况下，提出的时间分辨光谱学测量系统将使我们能够在很宽的时间范围内获得有机物以及新型纳米级发射器材料的激发态动力学的详细见解，特别是关于它们的电子偶极矩的重定向。为此，我们需要一个可调谐的脉冲激光系统，具有足够短的脉冲长度和足够的脉冲能量，在从紫外线到整个可见区域的宽光谱范围内。通过将其与现有的条纹相机系统相结合，我们将能够在宽时间窗口内研究各种发射器材料的发光动力学，从几百皮秒到毫秒（如果需要，甚至更长）。此外，计划的发光物质的辐射模式分析，特别是在激发态寿命期间可能的重新定向，需要具有优异成像质量的光谱仪连接到一个门控强化电荷耦合器件作为探测器。对于发射方向的研究，我们可以容忍在纳秒范围内时间分辨率略有下降；然而，通过设想的后焦平面成像的新设置，我们计划在一次曝光中捕捉相关的动量和能量范围。这将允许研究复杂发射系统中光激发的动态重定向过程。提出的新设置将加强该小组在有机和纳米尺度无机发射器材料取向研究领域的领先地位，并实现迄今为止不可用的新方法。

The Organic Semiconductors Group works on the understanding of elementary processes in light-emitting materials and, in particular, on the limitations concerning the efficiency of devices. One of our most important achievements in this field was the finding that many organic dyes used as light emitters in guest-host systems exhibit a non-isotropic orientation distribution of their optical transition dipole moments. These and related questions are subject of current and planned future research projects.In this context, the proposed measurement system for time-resolved optical spectroscopy will allow us to gain detailed insights into excited-state dynamics of organics as well as novel nano-scale emitter materials over a wide range in time and, specifically, with respect to reorientation of their electronic dipole moments.To this end, we need a tunable pulsed laser system with sufficiently short pulse length and enough pulse energy over a wide spectral range from the ultra-violet across the entire visible region. By combining it with an already existing streak camera system, we will be able to study luminescence dynamics of a broad range of emitter materials across a wide time window, spanning from a few hundred picoseconds to milliseconds (or longer if required).Furthermore, the planned radiation pattern analysis of the light-emitting species – and, in particular, possible reorientation of the same during the excited state lifetime – requires a spectrograph with excellent imaging quality connected to a gated intensified charge-coupled device as detector. For the investigation of emitter orientation, we can tolerate a slightly diminished time resolution in the nanosecond range; however, with the envisioned new setup for back focal plane imaging we plan to capture the relevant momentum and energy range in a single exposure. This will allow studying dynamic reorientation processes of optical excitations in complex emitter systems.The proposed new setup will strengthen the leading position of the group in the field of orientation studies of organic and nano-scale inorganic emitter materials and implement a novel method that is not available to date.