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arXiv 1005.0648cond-mat.soft
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均相分子和网络玻璃及聚合物中拉伸指数弛豫(SER)的微观特征

Microscopic Aspects of Stretched Exponential Relaxation (SER) in Homogeneous Molecular and Network Glasses and Polymers

J. C. Phillips

摘要:

由于SER理论仍然是一项正在进行的工作,这种现象本身可以说是科学中最古老的未解决的问题,因为它始于1847年的Kohlrausch。许多电学和光学现象都表现出SER,探测弛豫I(t)~ exp[-(t/τ)β],0 < β < 1。在这里,τ是一个材料敏感参数,用于讨论化学趋势。“形状”参数β是无量纲的,起着非平衡标度指数的作用;它的值,特别是在玻璃中,既有实际意义,又有理论意义。SER的数学复杂性是这样的,直到20世纪70年代才实现了对这个特殊函数的严格推导。20世纪70年代许多开创性工作的重点是电子电荷的空间弛豫,但SER是一种普遍现象,今天玻璃和深度过冷液体的原子和分子弛豫提供了最可靠的数据。随着数据库的增长,对定量理论的需求也在增加;这一需求最终被扩散到陷阱拓扑模型所满足,它产生了一个非常简单的形状参数β的表达式,由d*/(d* + 2)给出。乍一看,这个表达式似乎与d/(d + 2)相同,其中d是最初导出的实际空间维度。然而,最初的模型未能解释大部分数据库。在这里,早期评论的主题,基于观察,在存在短程力的情况下,只有d* = d = 3是实际的空间维度,而对于混合的短程和长程力,d* = fd = d/2,被应用于四个新的壮观的例子,事实证明,SER不仅用于质量控制的目的,也是为了在新的语境中定义玻璃杯的含义。(请参阅正文中的完整摘要)

英文摘要:

Because the theory of SER is still a work in progress, the phenomenon itself can be said to be the oldest unsolved problem in science, as it started with Kohlrausch in 1847. Many electrical and optical phenomena exhibit SER with probe relaxation I(t) ~ exp[-(t/τ)β], with 0 < β < 1. Here τ is a material-sensitive parameter, useful for discussing chemical trends. The "shape" parameter β is dimensionless and plays the role of a non-equilibrium scaling exponent; its value, especially in glasses, is both practically useful and theoretically significant. The mathematical complexity of SER is such that rigorous derivations of this peculiar function were not achieved until the 1970's. The focus of much of the 1970's pioneering work was spatial relaxation of electronic charge, but SER is a universal phenomenon, and today atomic and molecular relaxation of glasses and deeply supercooled liquids provide the most reliable data. As the data base grew, the need for a quantitative theory increased; this need was finally met by the diffusion-to-traps topological model, which yields a remarkably simple expression for the shape parameter β, given by d*/(d* + 2). At first sight this expression appears to be identical to d/(d + 2), where d is the actual spatial dimensionality, as originally derived. The original model, however, failed to explain much of the data base. Here the theme of earlier reviews, based on the observation that in the presence of short-range forces only d* = d = 3 is the actual spatial dimensionality, while for mixed short- and long-range forces, d* = fd = d/2, is applied to four new spectacular examples, where it turns out that SER is useful not only for purposes of quality control, but also for defining what is meant by a glass in novel contexts. (Please see full abstract in main text)

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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