Abstract Chemically stable and biocompatible gold nanorods (Au NRs) are an excellent building block for plasmonic-based applications, including surface-enhanced Raman spectroscopy (SERS). However, the quest for controlling the aspect ratio (AR) for desirable application needs an in-depth understanding of the synthesis procedure. In this article, the seed-mediated growth of Au NRs with a controlled AR is reported. Influencing reagents, including the seed concentration, are varied individually to unfurl the impact of them on AR. A subsequent optimized protocol is developed to achieve a fine-tuning in the longitudinal surface plasmonic resonance (LSPR) of Au NRs with a narrow distribution of NRs and minimal by-products. The effect of resonance of LSPR peaks closely tallying both 785 and 532 nm with laser excitations are studied for SERS applications using rhodamine 6G (R6G) dye. Furthermore, the molecular resonance of R6G analyte is achieved successfully with a 532 nm excitation laser to accomplish as high of 10−12 M, thanks to the suitable ARs and the surface-enhanced resonance Raman scatterings (SERRS) phenomenon. The enhancement factor is calculated to be 5 × 109, which allows Raman intensity mapping for a trace amount of R6G, demonstrating the potential utility of Au NRs for applications.

中文翻译：

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优化的 Au NRs 具有分子和纵向表面等离子体共振的高效 SERS 和 SERRS 性能

摘要 化学稳定和生物相容性的金纳米棒 (Au NRs) 是基于等离子体的应用的绝佳构建块，包括表面增强拉曼光谱 (SERS)。然而，为获得理想的应用而控制纵横比 (AR) 需要对合成过程有深入的了解。在本文中，报道了具有受控 AR 的 Au NRs 的种子介导生长。影响试剂，包括种子浓度，单独变化以展开它们对 AR 的影响。随后开发了一个优化的协议，以实现对 Au NRs 的纵向表面等离子体共振 (LSPR) 的微调，其 NRs 分布较窄，副产品最少。对于使用罗丹明 6G (R6G) 染料的 SERS 应用，研究了 785 和 532 nm 与激光激发密切相关的 LSPR 峰的共振效应。此外，由于合适的 AR 和表面增强共振拉曼散射 (SERRS) 现象，使用 532 nm 激发激光成功实现了 R6G 分析物的分子共振，达到 10-12 M。计算出的增强因子为 5 × 109，这允许对痕量 R6G 进行拉曼强度映射，证明了 Au NR 在应用中的潜在效用。