Cooperativity and the Freezing of Molecular Motion at the Glass Transition

作者：Bauer Th; Lunkenheimer P^*; Loidl A

来源：Physical Review Letters, 2013, 111(22): 225702.

DOI：10.1103/PhysRevLett.111.225702

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.

• 出版日期2013-11-25