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Study of the Spin Alignment in the Photo-Excited States of Organic High-Spin Molecules and Magnetic Polymers

有机高自旋分子和磁性聚合物光激发态自旋排列的研究

基本信息

批准号：
07454191
负责人：
TEKI Yoshio
金额：
$ 4.99万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454191/
关键词：
organic high-spin molecule molecular magnetism spin chemistry stable radical spin alignment photo-excited high-spin state Zero-field ODMR optical spectra 多スピン系有機分子光検出磁気共鳴蛍燐光スペクトル蛍光スペクトル

项目摘要

This project has been carried out in order to clarify the electronic states and the spin alignment on the photo-excited states of multi-spin open-shell organic molecules in which the spin correlation among the unpaired spins exists. We have succeeded to construct a high-sensitivity zero-field optically detected magnetic resonance apparatus (ODMR) which is very useful and dispensable to study the excited spin states. We have synthesized several model compounds for the study of their ground and excited spin states. I have investigated the magnetic and optical properties of a series of thioaminyl radical crystals, stable nitronylnitroxide radicals and the spin alignment of the organic high-spin molecules. The tree stable thioaminyls show ferromagnetic behaviors described using the one-dimentional Heisenberg model with the large ferromagnetic interaction of 2J/kbeta = 28.0, 11.4 and 3.6 K.The low-temperature susceptibility and heat capacity measure-ments of the crystal showing 2J/kbeta = 2 … More 8.0 reveals a magnetic phase transition at 0.4 K.For the unique organic high-spin molecule, 4T4'Q-ether, a quantum spin contraction phenomena has been discovered in its triplet ground state with, low-lying quintet and septet excited states. Using the above-mentioned ODMR apparatus and low-temperature optical spectroscopy, We have studied the photo-excited spin states of these compounds. We have succeeded to detect the phosphorescence spectra for biphenyl-3,3'-bisphenylmethylene, naphthalene-nitronylnitroxide radical, and Br-substituted, pyrene-nitronylnitroxide radical. This finding indicates that the existence of the photo-excited high-spin (S<greater than or equal>3/2) states, leading to the determination of the location of the excited high-spin states above the ground states. An ODMR spectrum was observed for Br-substituted pyrene-nitronylnitroxide radical. The detail study of the photo-excited high-spin state is in progress. The problems of the low efficiency of the intersystem-crossing and a strong spin forbidden effect between the excited doublet and excited quartet states were revealed. These findings lead to an important research subject for "the photo-excited spin science and spin chemistry". We also find out a clue to solving the low-efficiency intersystem crossing problem by the heavy atom substitution. The detail study of the titled research subject is now going in progress. This project has lead to a new development in the field of the spin chemistry as well as revealing the problem of the strong spin forbidden between the excited doublet and quarte Less

本项目的目的是研究多自旋开壳层有机分子的电子态和光激发态的自旋排列，其中不成对自旋之间存在自旋相关。我们成功地建立了一个高灵敏度的零场光探测磁共振装置（ODMR），这对研究自旋激发态是非常有用和方便的。我们已经合成了几种模型化合物，用于研究它们的基态和激发态。我研究了一系列硫代胺基自由基晶体、稳定的硝酰基氮氧自由基以及有机高自旋分子的自旋取向的磁性和光学性质。三种稳定的硫代胺基化合物具有铁磁行为，用一维Heisenberg模型描述，铁磁相互作用为2 J/kbeta = 28.0，11.4和3.6K，低温磁化率和热容的测量结果表明：2 J/kbeta = 2 ...更多信息 8.0对有机高自旋分子4 T4 'Q-醚，在其三重态基态、低激发态、五重态和七重态中发现了量子自旋收缩现象.利用上述ODMR装置和低温光谱，我们研究了这些化合物的光激发自旋态。我们成功地探测到了联苯-3，3 ′-二苯基亚甲基、萘硝酰基氮氧自由基和Br-取代芘硝酰基氮氧自由基的磷光光谱。这一发现表明了光激发高自旋（S3<greater than or equal>/2）态的存在，从而确定了激发高自旋态在基态之上的位置.观察到Br-取代的芘-硝酰基氮氧自由基的ODMR光谱。光激发高自旋态的详细研究正在进行中。发现了系统间跃迁效率低和激发二重态与激发四重态之间存在强烈的自旋禁戒效应等问题。这些发现为“光激发自旋科学和自旋化学”提供了一个重要的研究课题。同时也为解决低效率的系间穿越问题找到了一条线索。目前正在对该课题进行详细研究。这一项目在揭示激发态二重态与四重态之间强自旋禁戒问题的同时，也使自旋化学领域有了新的发展。