Study on Microscopic Solvation Effects on Nonradiative Processes

本研究项目旨在通过对含有芳香族发色团的溶剂化簇的实验研究，阐明芳香族分子中的非辐射过程如何以及为什么受到周围溶剂的影响。通过应用各种光谱方法，即，利用多重激光共振、质量选择性光电离和超快激光光谱等方法，获得了以下结果：1.研究了吖啶和9-吖啶酮的水合团簇，探讨了氢键网络中结构基元与发色团中非辐射过程之间的分子水平相关性。水合物的几何形状已确定通过比较实验数据（电子跃迁和荧光检测的红外光谱带移）与密度泛函理论计算。皮秒时间分辨测量表明，荧光寿命基本上取决于簇的大小以及氢键位点。关于Microsco 关于我们 pic溶剂化效应可以用（n，π^*）和（π，π^*）态的能量学来解释，这些态的特征是被氢键移动。2.重新研究了苯团簇在单体S_1-S_0区域的电子跃迁。已经发现，以前的大小分配接受了二十年需要进行纠正，根据详细检查的质量选择性holeburing光谱记录的各种同位素物种的二聚体和三聚体离子通道。对苯的三聚体和四聚体进行了新的分子分配，解决了迄今为止报道的实验结果和理论结果之间的矛盾。本文的数据还提供了团簇的几何结构和激发交换相互作用的信息。3.用皮秒时间分辨抽运-探测耗尽旋转相干光谱技术研究了含9-氰基蒽的溶剂化团簇的几何结构。特别地，非质子溶剂分子的结构基序，例如，CO2、乙腈和氟仿的反应动力学模型，为进一步探讨相关氰基芳烃簇合物的溶剂化结构与反应动力学之间的关系奠定了基础.少

The present research project aims to clarifying how and why nonradiative processes in aromatic molecules are influenced by solvents surrounding them through experimental investigations on solvated clusters containing aromatic chromophores. By applying various spectroscopic methods, i.e., multiple laser resonances, massselective photoionization, and ultrafast laser spectroscopy, the following results have been achieved.1.Hydrated clusters of acridine and 9-acridone have been studied to explore molecular-level correlation between structural motifs in hydrogen-bonding networks and nonradiative processes in the chromophores. Geometries of the hydrates have been determined by comparison of experimental data(band shifts in electronic transitions and fluorescence-detected infrared spectra)with density-functional-theory calculations. Pico-second time-resolved measurements have shown that fluorescence lifetimes depend substantially on cluster sizes as well as hydrogenbonding sites. The microsco … More pic solvation effects have been explained in terms of energetics relating to closely lying(n, π^*)and(π, π^*)states, which are characteristically shifted by hydrogen bonds.2.Electronic transitions of benzene clusters in the monomer S_1-S_0 region have been reinvestigated. It has been found that previous size-assignments accepted for two decades need to be corrected, based on detailed examination of mass-selective holeburing spectra recorded for various isotopic species of dimer and trimer ion channels. New assignments have been proposed for the benzene trimer and tetramer, which resolve contradictions between experimental and theoretical results reported so far. The present data also provide information on geometry and excitation exchange interactions of the clusters.3.Geometrical structure of solvated clusters containing 9-cyanoanthracene has been determined by rotational coherence spectroscopy implemented with pico-second time-resolved pump-probe depletion. In particular, structral motif for aprotic solvent molecules, e.g., carbon dioxide, acetonitrile, and fluoroform, has been established for the first time, which will be a solid foundation for discussing the relationship between reaction dynamics and solvation structure in clusters of related cyano-aromatics. Less