Electronic state and molecular rotation infullerene solid and related compounds

富勒烯分子在固体中具有大幅度的分子转动。这种分子的旋转能够影响固体中的电子状态，导致固体中的各种相变。本研究的目的是用核磁共振技术研究富勒烯在固体中的分子动力学。主要研究结果如下：1.利用NMR研究了固体C60、C70和C76的分子动力学和相变，特别是发现固体C76在135-170 K附近出现了与C76分子转动有关的相变。该温度远低于固体C_（60）和C_（70）的温度。2.用NMR研究了超导体Na_2AC_（60）（A=K，Rb，Cs）的电子态和C_（60）分子动力学。发现Na_2AC_（60）在室温以上为金属塑性晶体。在塑性相中，观察到非常大的13 C-NMR自旋晶格弛豫速率，表明存在异常的金属态。3.对高压加热制备的C60聚合物和硬碳进行了13 C-NMR研究，用核磁共振研究了氨化C60超导体中的C60和NH3分子的旋转，晶体及其对电子态的影响。

Fullerene molecules are expected to show large amplitude molecular rotation in solid. Such molecular rotation is able to affect the electronic states and lead to variety phase transitions in solid. The aim of the present study is to clarify the molecular dynamics of fullerene in solids by NMR technique. The main results are summarized as follows.1.The molecular dynamics and phase transition in solid C60, C70, and C76 were studied by NMR.Especially, we found that solid C76 shows a transition around 135-170 K related to C76 molecular rotation. This temperature is much lower than those of solid C60 and C70.2.Superconductors, Na2AC60 (A=K,Rb, Cs), were studied by NMR to obtain information on both the electronic state and C60 molecular dynamics. We found that Na2AC60 is metallic plastic crystal above room temperature. In the plastic phase, very large 13C-NMR spin lattice relaxation rate was observed, suggesting an anomalous metallic state.3.C60 polymer and hard carbon prepared by heating under high pressure were studied by 13C-NMR,which clarify the presence of sp2 and sp3 carbons and C60 molecular rotation in crystal.4.Ammoniated C60 superconductors were studied by NMR to clarify the C60 and NH3 molecular rotation in crystal and its effect on the electronic state.