Photoinduced processes in nitrogen-substituted aromatic molecules and their dimers: A joint experimental and theoretical investigation .

氮取代芳香族分子及其二聚体的光诱导过程：联合实验和理论研究。

• 批准号: 465716799
• 负责人: Professor Dr. Ingo Fischer
• 金额: --
• 依托单位: Institut für Physikalische und Theoretische Chemie
• 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/465716799?language=en
• 关键词: Photoinduced; processes; nitrogen; substituted; aromatic

In this project, we will investigate the photochemistry and photophysics in aromatic molecules containing nitrogen, so-called PANH (polycyclic aromatic nitrogen-containing hydrocarbons). A characteristic of the project is the close cooperation between theory and experiment. Data on isolated molecules and dimers permit a direct comparison with high-level computations and give insight into the intrinsic molecular properties in the absence of environmental influence. Time-resolved photoionization and photoelectron imaging in a free jet will be complemented by quantum-classical dynamics simulations, an approach that permits the direct comparison with experimental observables, such as time-delay traces or photoelectron spectra. As picosecond pulses with a time-resolution of around 4 ps and a bandwidth of 15-20 cm-1 are employed, it is possible to investigate the dependence of the photodynamics on the excess energy deposited in the molecules.Although fundamental questions are in the center of our research, the program is also moti-vated by the relevance of nitrogen-containing molecules for materials science. For example, replacement of a carbon atom by a nitrogen can turn a predominantly hole-conducting polycyclic aromatic hydrocarbon (PAH) into a n-type semiconductor with improved electron conduction. Furthermore, PANH play an important role in astrochemistry and are considered as carriers of the unidentified infrared bands (UIB). In our research program we will address the following questions: a) the sequence and the character of excited electronic states in PAH is modified by the introduction of an N-atom. We will therefore investigate the electronic structure and dynamics in PANH as a function of the position of the nitrogen atom. Initially, we will study the sequence phenanthrene/ phenanthridine/ benzoquinoline and then extend our work to tetracene- and pentacene-derivatives that will be synthesized in our group. b) we will investigate the impact of the substitution by nitrogen on the structure of PANH di-mers and in particular on the formation of excimers, dimers that interact weakly in the ground state, but strongly in the electronically excited state. In particular aza-tetracenes and aza-pentacenes will be relevant, because both chromophore are considered as models for singlet fission (SF). In this process a one-electron excitation leads to the formation of two excitons, which can lead to an increased efficiency of solar cells using suitable materials. Excimer for-mation can be considered to be the first step towards SF. c) heterocycles with relevance for material science like PTCDA and PBI will be transferred into the gas phase by laser desorption. Subsequently, the photophysics of the molecules and their dimers will be investigated experimentally and theoretically.

在本计画中，我们将探讨含氮芳香族分子，即所谓的多环芳香族含氮碳氢化合物（PANH）的光化学与光物理性质。该项目的一个特点是理论与实验的密切合作。孤立的分子和二聚体的数据允许直接与高层次的计算比较，并在没有环境影响的情况下深入了解内在的分子性质。时间分辨的光电离和光电子成像在自由射流将补充量子经典动力学模拟，一种方法，允许直接比较与实验观测，如时间延迟的痕迹或光电子光谱。由于采用了时间分辨率约为4 ps，带宽为15-20 cm-1的皮秒脉冲，因此可以研究光动力学对沉积在分子中的过剩能量的依赖性。虽然我们的研究中心是基础问题，但该计划也受到含氮分子与材料科学相关性的推动。例如，用氮取代碳原子可以将主要空穴传导的多环芳烃（PAH）转变为具有改善的电子传导的n型半导体。 此外，PANH在天体化学中起着重要的作用，被认为是未识别红外波段（UIB）的载体。在我们的研究计划中，我们将解决以下问题：a）通过引入一个N原子来改变PAH中激发电子态的顺序和性质。因此，我们将研究的电子结构和动力学在PANH作为氮原子的位置的函数。首先，我们将研究菲/菲啶/苯并喹啉的序列，然后将我们的工作扩展到并四苯和并五苯衍生物，这些衍生物将在我们的小组中合成。B）我们将研究氮取代对PANH二聚体结构的影响，特别是对激基异构体的形成的影响，激基异构体是在基态下相互作用较弱，但在电子激发态下相互作用较强的二聚体。 特别地，氮杂并四苯和氮杂并五苯将是相关的，因为两种发色团都被认为是单线态裂变（SF）的模型。在该过程中，单电子激发导致形成两个激子，这可以导致使用合适材料的太阳能电池的效率提高。准分子的形成可以被认为是迈向SF的第一步。c）与材料科学相关的杂环如PTCDA和PBI将通过激光解吸转化为气相。随后，分子及其二聚体的量子物理将进行实验和理论研究。