Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech , DK-2800, Kgs Lyngby, Denmark.
Nano Lett. 2014 May 14;14(5):2318-21. doi: 10.1021/nl4046679. Epub 2014 Apr 7.
We demonstrate the direct photothermal probing and mapping of single plasmonic nanostructures via the temperature-induced detuning of nanomechanical string resonators. Single Au nanoslits and nanorods are illuminated with a partially polarized focused laser beam (λ = 633 nm) with irradiances in the range of 0.26-38 μW/μm(2). Photothermal heating maps with a resolution of ∼375 nm are obtained by scanning the laser over the nanostructures. Based on the string sensitivities, absorption efficiencies of 2.3 ± 0.3 and 1.1 ± 0.7 are extracted for a single nanoslit (53 nm × 1 μm) and nanorod (75 nm × 185 nm). Our results show that nanomechanical resonators are a unique and robust analysis tool for the low-power investigation of thermoplasmonic effects in plasmonic hot spots.
我们通过纳米机械弦谐振器的温度诱导频偏，展示了对单个等离子体纳米结构的直接光热探测和成像。利用强度在 0.26-38 μW/μm(2)范围内的部分偏振聚焦激光束（λ = 633nm）对单个 Au 纳米狭缝和纳米棒进行照射。通过在纳米结构上扫描激光，获得了分辨率约为 375nm 的光热加热图。基于弦灵敏度，从单个纳米狭缝（53nm×1μm）和纳米棒（75nm×185nm）中分别提取了 2.3±0.3 和 1.1±0.7 的吸收效率。我们的结果表明，纳米机械谐振器是一种独特而稳健的分析工具，可用于在等离子体热点中对热等离子体效应进行低功率研究。
