Single-molecule detection by surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that is of interest for the sensor development field. An important aspect of optimizing the materials used in SERS-based sensors is the ability to have a high density of “hot spots” that enhance the SERS sensitivity to the single-molecule level. Photodeposition of gold (Au) nanoparticles through electric-field-directed self-assembly on a periodically proton-exchanged lithium niobate (PPELN) substrate provides conditions to form well-ordered microscale features consisting of closely packed Au nanoparticles. The resulting Au nanoparticle microstructure arrays (microarrays) are plasmon-active and support nonresonant single-molecule SERS at ultralow concentrations (<10^–9–10^–13 M) with excitation power densities <1 × 10^–3 W cm^–2 using wide-field imaging. The microarrays offer excellent SERS reproducibility, with an intensity variation of <7.5% across the substrate. As most biomarkers and molecules do not support resonance enhancement, this work demonstrates that PPELN is a suitable template for high-sensitivity, nonresonant sensing applications.

中文翻译：

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铁电定义的金纳米颗粒微阵列的单分子非共振宽场表面增强拉曼散射

表面增强拉曼散射 (SERS) 的单分子检测是一种强大的光谱技术，引起了传感器开发领域的兴趣。优化基于 SERS 的传感器所用材料的一个重要方面是能够具有高密度的“热点”，从而将 SERS 灵敏度提高到单分子水平。通过电场引导自组装在周期性质子交换铌酸锂 (PPELN) 基板上光沉积金 (Au) 纳米粒子，为形成由紧密堆积的金纳米粒子组成的有序微米特征提供了条件。^{由此产生的金纳米粒子微结构阵列（微阵列）具有等离激元活性，并支持超低浓度（<10 –9} –10 ^–13 M ）的非共振单分子 SERS，激发功率密度 <1 × 10 ^–3 W cm ^–2，使用宽-场成像。该微阵列具有出色的 SERS 重现性，基板上的强度变化 <7.5%。由于大多数生物标志物和分子不支持共振增强，这项工作表明 PPELN 是高灵敏度、非共振传感应用的合适模板。