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

这项工作是为了阐明多自旋开壳有机分子中存在自旋关联的多自旋开壳有机分子的电子态和自旋排列。我们已经成功地构建了一台高灵敏度的零场光学探测磁共振装置(ODMR)，这对于研究激发自旋态是非常有用和必不可少的。我们合成了几个模型化合物来研究它们的基态和激发自旋态。我研究了一系列硫胺基自由基晶体、稳定的硝基氮氧自由基和有机高自旋分子的自旋排列的磁性和光学性质。树状结构的硫代胺表现出一维海森堡模型的铁磁行为，其大的铁磁相互作用为2J/kβ=28.0，11.4和3.6K。低温磁化率和热容测量为2J/kβ=2…对于唯一的有机高自旋分子--4T4‘Q-乙醚，在其三重基态、五重激发态和七重激发态中发现了量子自旋收缩现象。利用上述的ODMR装置和低温光谱学，我们研究了这些化合物的光激发自旋态。我们成功地检测到了联苯-3，3‘-二苯亚甲基、萘-硝基氮氧自由基和溴取代的芘-硝基氮氧自由基的磷光光谱。这一发现表明，光激发高自旋态(S和lt；大于或等于&gt；3/2)态的存在，导致了激发高自旋态在基态上方的位置的确定。观察到了溴取代的芘-硝基氮氧自由基的ODMR谱。对光激发高自旋态的详细研究正在进行中。揭示了激发二重态和激发四重态之间的系间交叉效率低和自旋禁忌效应强的问题。这些发现成为“光激发自旋科学和自旋化学”的一个重要研究课题。我们还找到了通过重原子取代来解决低效系间交叉问题的线索。题为研究课题的详细研究目前正在进行中。这个项目在自旋化学领域取得了新的进展，揭示了激发二重态和少四重态之间的强自旋禁忌问题

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