Self-Organized Fractal Structures on Plasma-Exposed Silver Surface.
Self-Organized Fractal Structures on Plasma-Exposed Silver Surface.
复制标题
暴露于等离子体的银表面的自组织分形结构
DOI：
10.3389/fchem.2021.816811
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发表时间：
2021
影响因子：
5.5
通讯作者：
Chen B
中科院分区：
文献类型：
--
作者：
Kan X;Chen K;Yin C;Yang Y;Shan M;Wang H;Han Q;Chen B
首次在正电晕处理的银膜上观察到了平面分形结构。由于正极性电场驱动下的大量正离子，表面改性主要由等离子体氧化作用引起，形成了大规模的具有自相似性和层次性的枝晶图案。相反，负电晕放电条件下，负离子占主导地位的等离子体-膜相互作用，导致不同的表面形貌没有分形特征。提出了一种基于改进的扩散限制聚集（DLA）理论的生长模型来描述树枝状分形结构的形成，而其背后的物理过程归因于表面粗糙度周围正离子的电场定向扩散。数值模拟验证了树枝状图案中的高密度热点，这可能使分形光子超材料的潜在应用。
Planar fractal microstructure is observed on the silver film treated by positive corona discharge for the first time. Due to the abundant positive ions driven by the electrical field of positive polarity, surface modification is mainly induced by the plasma oxidation effect, resulting in a large scale of dendritic pattern with self-similarity and hierarchy. In contrast, negative ions dominate the plasma-film interaction under negative corona discharge condition, leading to a different surface morphology without fractal characteristics. A growth model based on the modified diffusion-limited aggregation (DLA) theory is proposed to describe the formation of the dendritic fractal structure, whilst the physics behind is attributed to the electric field directed diffusion of the positive ions around the surface roughness. Numerical simulation verifies the high density of the hot spot in the dendritic pattern, which may enable potential applications in fractal photonic metamaterials.