Enhanced dispersion in an oscillating array of harmonic traps
Enhanced dispersion in an oscillating array of harmonic traps
复制标题
增强谐波陷阱振荡阵列中的色散
DOI：
10.1103/physreve.107.014601
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发表时间：
2023
影响因子：
2.4
通讯作者：
Takatori, Sho C.
中科院分区：
文献类型：
--
作者：
Barakat, Joseph M.;Takatori, Sho C.
采用实验、理论和模拟相结合的方法，研究了胶体粒子在由光钳产生的周期性振荡谐振子阵列中的弥散行为。在陷阱振荡的存在下，观察到了非单调和各向异性的色散。令人惊讶的是，最坚硬的陷阱在一个临界频率上产生了最大的色散，并且粒子在振荡方向上的扩散速度明显快于那些经历被动Stokes-Einstein-Sutherland扩散的粒子。利用广义泰勒色散理论和布朗动力学模拟，建立了粒子有效扩散系数与陷阱刚度和振荡频率的函数关系的理论预测。理论和模拟都显示出与实验很好的一致性，并揭示了一种预测动态外场中胶体扩散显著增强的“弹弓”机制。
Experiment, theory, and simulation are employed to understand the dispersion of colloidal particles in a periodic array of oscillating harmonic traps generated by optical tweezers. In the presence of trap oscillation, a nonmonotonic and anisotropic dispersion is observed. Surprisingly, the stiffest traps produce the largest dispersion at a critical frequency, and the particles diffuse significantly faster in the direction of oscillation than those undergoing passive Stokes-Einstein-Sutherland diffusion. Theoretical predictions for the effective diffusivity of the particles as a function of trap stiffness and oscillation frequency are developed using generalized Taylor dispersion theory and Brownian dynamics simulations. Both theory and simulation demonstrate excellent agreement with the experiments, and reveal a “slingshot” mechanism that predicts a significant enhancement of colloidal diffusion in dynamic external fields.