C_(60)取向驰豫的极限动力学研究

Orientational relaxation of C_(60) researched by extremal dynamic model

用极限动力学模型研究了C60 分子在有序 -无序相变和玻璃态相变间的驰豫行为 .结果表明 :KWW方程的非指数因子 β与双取向态间的能极差有关 ,则其值与实验结果相符 ;导出了 38°取向态的密度表达式 ,计算结果在 85K和 90K与实验值吻合 ;讨论了双能级的C60 分子从非平衡态到平衡态的驰豫行为 ,其总的驰豫时间决定于其中一个较短的驰豫时间 ,伸展指数形式保持不变 .在 85K以下 ,具有较长驰豫时间的近邻分子会咬合跳跃单元以冻结取向态间的比例变化 .

Relaxation behavior of C 60 molecules between order-disorder phase transition and glassy transition is studied by extremal dynamic model. The novel explanation for non-exponent factor β is proposed due to the energy level difference between 38° and 98° orientational states. The population of 38° orientational state is calculated in the theory and coincides with experiment result rather well at glassy transition. The relaxation behavior from non-equilibrium state is discussed that stretched exponential form keeps constance. The larger relaxation time and more neighbor conformers meshing with jump unit below 85?K are helpful to explain the freezing of orientational disorder.