Abstract The present paper reflects on the results of sytematic studies that link SERS responses of probe molecules with the topographical features of three different SERS active substrates prepared through integration of Langmuir-Blodgett and self-assembly technique. The topographies of the substrates are mapped directly from the AFM images. Relevant topographical parameters of three efficient SERS active substrates are elaborately investigated in terms of lateral correlation length, the interface width, Hurst and Lyapunov exponents. The lateral correlation lengths have been estimated from auto-correlation function, while the interface width and respective values of Hurst exponents are explored from the height-height correlation function. The comparative studies on all the three substrates suggest that the lateral correlation length in the range 136–286 nm favour SERS activities. Estimations of Hurst exponents > 0.5 for all the above referred three substrates further signify prevalence of long range correlations driven by super diffusion of the nanocolloids on the respective LB film substrates. Moreover, all the substrates exhibit fractal nature of the plasmonic aggregates that may favour the suitable architecture responsible for SERS enhancements. The chaotic behaviours of the as prepared substrates have also been estimated from Lyapunov exponents and 2D phase space trajectories. The paper thus essentially provides a one to one mapping between SERS spectroscopy at the molecular scale with the corresponding microscopy of the substrates wherein the probe molecules are adsorbed. These information may find relevance in the pragmatic fabrication of future SERS active substrates for sensing and diagnostic applications.

中文翻译：

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探针分子的 SERS 响应如何取决于底物的形貌？一个相对的探索

摘要 本文反映了将探针分子的 SERS 响应与通过 Langmuir-Blodgett 和自组装技术集成制备的三种不同 SERS 活性基底的地形特征联系起来的系统研究结果。基板的形貌直接从 AFM 图像映射。在横向相关长度、界面宽度、Hurst 和 Lyapunov 指数方面，精心研究了三种高效 SERS 活性衬底的相关形貌参数。横向相关长度是从自相关函数估计的，而界面宽度和赫斯特指数的相应值是从高度-高度相关函数中探索的。对所有三种底物的比较研究表明，136-286 nm 范围内的横向相关长度有利于 SERS 活动。对于所有上述三种基材，Hurst 指数的估计值 > 0.5 进一步表明由纳米胶体在各自 LB 薄膜基材上的超扩散驱动的长程相关性的普遍存在。此外，所有基底都表现出等离子体聚集体的分形性质，这可能有利于负责 SERS 增强的合适结构。所制备的衬底的混沌行为也已从 Lyapunov 指数和 2D 相空间轨迹估计。因此，该论文基本上提供了分子尺度上的 SERS 光谱与其中吸附了探针分子的基底的相应显微术之间的一对一映射。