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中国物理学会期刊

光场调控的活性粒子体系的动态自组装

CSTR: 32037.14.aps.74.20241556

Dynamic self-assembly of active particle systems controlled by light fields

CSTR: 32037.14.aps.74.20241556
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  • 活性粒子体系是一类由自驱动布朗粒子组成的非平衡系统, 体系粒子之间通过相互作用可以表现出众多奇特的集体行为. 本文基于布朗动力学模拟, 研究了光场调控的活性粒子体系有序结构的形成和转变机制. 研究发现, 活性粒子在光场调控下发生了大尺度的相分离行为, 形成了特定的有序结构, 并实现了多种有序结构的动态转变. 本文系统地探讨了光场对这一动态相转变的影响和调控机制. 研究结果为活性体系群体结构的精确调控以及微纳米智能器件的制造提供了重要参考.

     

    Active particle systems are nonequilibrium systems composed of self-propelled Brownian particles, where interactions between particles can give rise to various collective behaviors. This study, based on Brownian dynamics simulations, explores the effects of light intensity, rotational diffusion coefficient, and the width and spacing of illuminated regions on the aggregation structures of the system. First, this study examines the influence of light intensity on aggregation structures under different rotational diffusion coefficients, finding that as the rotational diffusion coefficient increases, the system gradually stabilizes. This stabilization is attributed to the reduced collision effects among particles at higher diffusion coefficients. Under suitable rotational diffusion coefficients, gradually increasing the ratio of longitudinal to transverse light-induced self-propulsion forces leads to a transition in the system’s aggregation structure from a transverse stripe structure configuration to a tic-tac-toe structure, ultimately resulting in a longitudinal stripe structure. This indicates that the system’s aggregation structure can be effectively controlled by changing the relative light intensity of the longitudinal and transverse illumination. From a dynamical perspective, an unstable structure consistently exhibits a super-diffusive behavior throughout the simulations, while stable structure transitions from initial super-diffusion to normal diffusion, indicating that under steady state conditions, particles aggregate in the shaded regions, exhibiting Brownian motion. To further investigate the influence of light field on collective particle behavior, in this study the width of the illuminated region and the spacing between adjacent illuminated regions are systematically varied, finding that the overall trends are consistent with previous conclusions. It is also observed that wider illumination regions with narrower spacing contribute to the formation of tic-tac-toe structures, while narrower illumination regions with wider spacing give rise to a novel structure—checkerboard structures. This study investigates the phase separation behavior of particles in complex optical field environments, providing some valuable ideas for controlling aggregation states in active particle systems.

     

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