Department of Physics and Astronomy, Shull Wollan Center-Joint Institute of Neutron Science, University of Tennessee, Knoxville, Tennessee 37996, USA.
Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
Phys Rev Lett. 2018 Mar 30;120(13):135502. doi: 10.1103/PhysRevLett.120.135502.
The de Gennes narrowing phenomenon is frequently observed by neutron or x-ray scattering measurements of the dynamics of complex systems, such as liquids, proteins, colloids, and polymers. The characteristic slowing down of dynamics in the vicinity of the maximum of the total scattering intensity is commonly attributed to enhanced cooperativity. In this Letter, we present an alternative view on its origin through the examination of the time-dependent pair correlation function, the van Hove correlation function, for a model liquid in two, three, and four dimensions. We find that the relaxation time increases monotonically with distance and the dependence on distance varies with dimension. We propose a heuristic explanation of this dependence based on a simple geometrical model. This finding sheds new light on the interpretation of the de Gennes narrowing phenomenon and the α-relaxation time.
德热纳变窄现象经常通过中子或 X 射线散射测量复杂系统的动力学来观察，如液体、蛋白质、胶体和聚合物。在总散射强度最大值附近，动力学的特征减速通常归因于增强的协同作用。在这封信中，我们通过检查二维、三维和四维模型液体的时变对关联函数和范霍夫相关函数，提供了对其起源的另一种看法。我们发现，弛豫时间随距离单调增加，而距离的依赖性随维度而异。我们基于一个简单的几何模型提出了对这种依赖性的启发式解释。这一发现为德热纳变窄现象和 α 弛豫时间的解释提供了新的思路。
