Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany.
Phys Rev Lett. 2013 Nov 27;111(22):225702. doi: 10.1103/PhysRevLett.111.225702. Epub 2013 Nov 25.
The slowing down of molecular dynamics when approaching the glass transition generally proceeds much stronger than expected for thermally activated motions. This strange phenomenon can be formally ascribed to a temperature-dependent activation energy E(T). In the present work, via measurements of the third-order nonlinear dielectric susceptibility, we deduce the increase of the number of correlated molecules N(corr) when approaching the glass transition and find a surprisingly simple correlation of E(T) and N(corr)(T). This provides strong evidence that the noncanonical temperature development of glassy dynamics is caused by a temperature-dependent energy barrier arising from the cooperative motion of ever larger numbers of molecules at low temperatures.
当接近玻璃化转变时，分子动力学的减缓通常比热激活运动预期的要强得多。这种奇怪的现象可以形式上归因于与温度有关的激活能 E(T)。在本工作中，通过测量三阶非线性介电常数的灵敏度，我们推断出在接近玻璃化转变时相关分子的数量 N(corr)的增加，并发现 E(T)和 N(corr)(T)之间存在惊人的简单相关性。这有力地证明了玻璃态动力学的非正则温度发展是由低温下越来越多的分子协同运动引起的与温度有关的能量势垒造成的。
