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引用次数: 0
摘要
最近的一项突破性实验研究[Lyons 等人,Phys. Rev. X 14(1), 011017 (2024)]报告了测量单分子折叠转变和双稳态势中布朗粒子试图穿越活化势垒失败的时间长度和空间范围(即 "循环")。然而,在扩散动力学模型中,由于障碍区边界的再穿越,这两个量平均都正好为零。也就是说,具有无限空间和时间分辨率的观察者会发现有限环路并不存在(或者更准确地说,形成了一个度量为零的集合)。在这里,我们将有限的实验分辨率所造成的边界 "模糊性 "考虑在内,对实验进行了描述,并展示了在时间和空间上定位越过障碍的点的实验不确定性是如何导致可观测的回路时间和大小分布的。虽然这些分布通常取决于实验分辨率,但在某些情况下,这种依赖性可能只是一个简单的分辨率依赖因子,因此,实验确实探究了越障动力学的固有特性。
The significance of fuzzy boundaries of the barrier regions in single-molecule measurements of failed barrier crossing attempts.
A recent ground-breaking experimental study [Lyons et al., Phys. Rev. X 14(1), 011017 (2024)] reports on measuring the temporal duration and the spatial extent of failed attempts to cross an activation barrier (i.e., "loops") for a folding transition in a single molecule and for a Brownian particle trapped within a bistable potential. Within the model of diffusive dynamics, however, both of these quantities are, on average, exactly zero because of the recrossings of the barrier region boundary. That is, an observer endowed with infinite spatial and temporal resolution would find that finite loops do not exist (or, more precisely, form a set of measure zero). Here we develop a description of the experiment that takes the "fuzziness" of the boundaries caused by finite experimental resolution into account and show how the experimental uncertainty of localizing the point, in time and space, where the barrier is crossed leads to observable distributions of loop times and sizes. Although these distributions generally depend on the experimental resolution, this dependence, in certain cases, may amount to a simple resolution-dependent factor and, therefore, the experiments do probe inherent properties of barrier crossing dynamics.
期刊介绍:
The Journal of Chemical Physics publishes quantitative and rigorous science of long-lasting value in methods and applications of chemical physics. The Journal also publishes brief Communications of significant new findings, Perspectives on the latest advances in the field, and Special Topic issues. The Journal focuses on innovative research in experimental and theoretical areas of chemical physics, including spectroscopy, dynamics, kinetics, statistical mechanics, and quantum mechanics. In addition, topical areas such as polymers, soft matter, materials, surfaces/interfaces, and systems of biological relevance are of increasing importance.
Topical coverage includes:
Theoretical Methods and Algorithms
Advanced Experimental Techniques
Atoms, Molecules, and Clusters
Liquids, Glasses, and Crystals
Surfaces, Interfaces, and Materials
Polymers and Soft Matter
Biological Molecules and Networks.