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

本课题的目的是澄清多自旋开壳有机分子光激发态上的电子态和自旋排列，其中存在未配对自旋之间的自旋相关。我们成功地构建了一个高灵敏度的零场光探测磁共振仪（ODMR），这对于研究激发自旋态是非常有用的。我们合成了几种模型化合物来研究它们的基态和激发态。我研究了一系列硫胺基自由基晶体的磁性和光学性质，稳定的硝基氮氧化物自由基和有机高自旋分子的自旋排列。三种稳定的硫胺基表现出用一维Heisenberg模型描述的铁磁行为，其铁磁相互作用为2J/kbeta = 28.0, 11.4和3.6 K。晶体的低温磁化率和热容测量显示2J/kbeta = 2…More 8.0，在0.4 K时发生磁相变。对于独特的有机高自旋分子4t4’q -醚，在其三重态基态、低五重态和七重激发态中发现了量子自旋收缩现象。利用上述ODMR装置和低温光谱学，我们研究了这些化合物的光激自旋态。我们成功地检测了联苯-3,3'-双苯亚甲基萘-硝基氮氧化物自由基和溴取代的芘-硝基氮氧化物自由基的磷光光谱。这一发现表明了光激发高自旋（S<大于等于>3/2）态的存在，从而确定了激发高自旋态在基态之上的位置。对br取代芘-硝基氮氧化物自由基进行了ODMR谱分析。光激发高自旋态的详细研究正在进行中。揭示了系统间交叉效率低、激发态与激发态之间存在强自旋禁止效应等问题。这些发现为“光激发自旋科学与自旋化学”开辟了一个重要的研究课题。我们还发现了用重原子取代来解决低效系间交叉问题的一条线索。标题研究课题的详细研究正在进行中。该项目揭示了受激重态和少夸脱态之间的强自旋禁止问题，并为自旋化学领域带来了新的发展

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