Measurement system for time-resolved optical spectroscopy

有机半导体小组致力于了解发光材料的基本工艺，特别是关于器件效率的限制。我们在这一领域最重要的成就之一是发现许多有机染料作为客体-主体体系的光发射体，其光学跃迁偶极矩呈现出非各向同性的取向分布。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。在这种背景下，所提出的时间分辨光学光谱测量系统将使我们能够在很大范围内深入了解有机物和新型纳米发射材料的激发态动力学，特别是关于其电子偶极矩的重新定向。为此，我们需要一个脉冲激光系统，该系统具有足够短的脉冲长度和足够的脉冲能量，从紫外光到整个可见光区的宽光谱范围内。通过将它与现有的条纹相机系统相结合，我们将能够在从几百皮秒到毫秒(如果需要的话)的宽时间窗口内研究各种发射体材料的发光动力学。此外，计划中的发光物种的辐射模式分析-特别是在激发态寿命期间可能对其进行重新定向-需要具有良好成像质量的光谱仪作为探测器连接到门控增强型电荷耦合器件。对于发射器方向的研究，我们可以容忍在纳秒范围内略有降低的时间分辨率；然而，随着设想的背焦平面成像的新设置，我们计划在一次曝光中捕获相关的动量和能量范围。这将使研究复杂发射系统中光激发的动态重定向过程成为可能。建议的新设置将加强该小组在有机和纳米级无机发射材料定向研究领域的领先地位，并实现一种迄今为止尚不存在的新方法。

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.