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Search for Photochemical Processes Peculiar to Excited Triplet Molecules and Selective Properties

寻找激发三重态分子特有的光化学过程和选择性特性

基本信息

批准号：
13440178
负责人：
BABA Masaaki
金额：
$ 9.73万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

In this project we focused on aromatic carbonyl molecules and investigated the excited state dynamics, particularly the intersystem crossing by the analysis of the vibronic structure in the excited triplet state. The triplet molecule emits phosphorescence with the very long Lifetime. We have developed laser spectroscopy system by which we can detect phosphorescence sensitively in a supersonic jet, and observed high resolution phosphorescence excitation spectra for a number of molecules. The typical molecule is benzaldehyde and we have observed the accurate spectra in the wide wavelength region. We also performed the quantum chemical molecular orbital calculations and assigned the vibrational levels in the excited states. The S1 state is nπ^*, and S_2 is ππ^*. Both are strongly coupled with the triplet states and show fast iutersystem crossing. As a result, fluorescence from the singlet state is weak, but phosphorescence from the triplet is very strong. We analyzed the deuterated compound and the rate of the iutersystem crossing was not changed by the deuterations. In pyridinecarboxyaldehyde, which is the nitrogen substituted compound, we found two nπ^* states. The intersystem crossing is suppressed in the lower energy, but enhanced in the higher energy region. As the molecular size becomes larger, the photochemical processes are expected to be faster because the level number is increased. However, it was not so fast in 1indanone and 1tetralone in which the aliphatic ring is attached. In contrast with this, the intersystem crossing is very fast in xanthone. It is concluded that the properties of the triplet molecules are various and peculiar for each compound. It is necessary to apply this to chemical reaction by probing the origin of the variety.

在这个项目中，我们专注于芳族羰基分子，并研究了激发态动力学，特别是通过分析激发三重态中的振动结构的系间交叉。三重态分子具有很长的磷光寿命。我们研制了一套能灵敏地探测超音速射流中磷光的激光光谱系统，并观测到一些分子的高分辨磷光激发光谱。典型的分子是苯甲醛，我们已经观察到在宽波长范围内的准确光谱。我们还进行了量子化学分子轨道计算，并指定了激发态的振动能级。S1态是nπ^*，S_2是ππ^*。两者都与三重态强耦合，并显示出快速的离子系统交叉。结果，来自单重态的荧光很弱，但来自三重态的磷光很强。我们分析了氘代化合物，氘代化合物的氘系交叉率没有改变。在氮取代的吡啶甲醛中，我们发现了两个nπ^* 态。在低能区系间穿越被抑制，但在高能区增强。随着分子尺寸变大，光化学过程预计会更快，因为能级数增加。而1-茚酮和1-四氢萘酮中的脂肪环则不那么快。与此相反，在氧杂蒽酮中，系间杂交非常快。结果表明，三重态分子的性质各不相同，且各不相同。有必要通过探索该品种的起源将其应用于化学反应。