Mallamace Francesco, Corsaro Carmelo, Leone Nancy, Villari Valentina, Micali Norberto, Chen Sow-Hsin
1] Dipartimento di Fisica e Scienze della Terra, Università di Messina I-98168, Messina, Italy [2] Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge MA 02139.
Dipartimento di Fisica e Scienze della Terra, Università di Messina I-98168, Messina, Italy.
Sci Rep. 2014 Jan 17;4:3747. doi: 10.1038/srep03747.
The dynamics of supercooled ortho-terphenyl has been studied using photon-correlation spectroscopy (PCS) in the depolarized scattering geometry. The obtained relaxation curves are analyzed according to the mode-coupling theory (MCT) for supercooled liquids. The main results are: i) the observation of the secondary Johari-Goldstein relaxation (β) that has its onset just at the dynamical crossover temperature TB (TM > TB > Tg); ii) the confirmation, of the suggestion of a recent statistical mechanical study, that such a molecular system remains ergodic also below the calorimetric glass-transition temperature Tg. Our experimental data give evidence that the time scales of the primary (α) and this secondary relaxations are correlated. Finally a comparison with recent PCS experiments in a colloidal system confirms the primary role of the dynamical crossover in the physics of the dynamical arrest.
利用光子相关光谱法（PCS）在去极化散射几何条件下研究了过冷邻三联苯的动力学。根据过冷液体的模式耦合理论（MCT）对所得的弛豫曲线进行了分析。主要结果如下：i）观察到二级乔哈里-戈尔茨坦弛豫（β），其起始点恰好在动力学交叉温度TB（TM > TB > Tg）处；ii）证实了最近一项统计力学研究的建议，即这样的分子体系在量热玻璃化转变温度Tg以下也保持遍历性。我们的实验数据表明一级（α）弛豫和二级弛豫的时间尺度是相关的。最后，与最近在胶体系统中进行的PCS实验的比较证实了动力学交叉在动力学阻滞物理过程中的主要作用。
