Payne Lukas, Zoriniants George, Masia Francesco, Arkill Kenton P, Verkade Paul, Rowles Darren, Langbein Wolfgang, Borri Paola
Cardiff University School of Biosciences, Museum Avenue, Cardiff CF10 3AX, United Kingdom.
Faraday Discuss. 2015;184:305-20. doi: 10.1039/c5fd00079c. Epub 2015 Sep 29.
We report a wide-field imaging method to rapidly and quantitatively measure the optical extinction cross-section σ(ext) (also polarisation resolved) of a large number of individual gold nanoparticles, for statistically-relevant single particle analysis. We demonstrate a sensitivity of 5 nm(2) in σ(ext), enabling detection of single 5 nm gold nanoparticles with total acquisition times in the 1 min range. Moreover, we have developed an analytical model of the polarisation resolved σ(ext), which enabled us to extract geometrical particle aspect ratios from the measured σ(ext). Using this method, we have characterized a large number of nominally-spherical gold nanoparticles in the 10-100 nm size range. Furthermore, the method provided measurements of in-house fabricated nanoparticle conjugates, allowing distinction of individual dimers from single particles and larger aggregates. The same particle conjugates were investigated correlatively by phase-resolved transient resonant four-wave mixing micro-spectroscopy. A direct comparison of the phase-resolved response between single gold nanoparticles and dimers highlighted the promise of the four-wave mixing technique for sensing applications with dimers as plasmon rulers.
我们报道了一种宽场成像方法，用于快速、定量地测量大量单个金纳米颗粒的光学消光截面σ(ext)（也可分辨偏振），以进行具有统计相关性的单颗粒分析。我们展示了σ(ext)的灵敏度为5 nm(2)，能够在总采集时间为1分钟左右的情况下检测单个5 nm金纳米颗粒。此外，我们开发了一种分辨偏振的σ(ext)分析模型，这使我们能够从测量的σ(ext)中提取颗粒的几何纵横比。使用这种方法，我们对大量尺寸在10 - 100 nm范围内的标称球形金纳米颗粒进行了表征。此外，该方法还对内部制备的纳米颗粒缀合物进行了测量，能够区分单个二聚体与单个颗粒及更大的聚集体。通过相分辨瞬态共振四波混频显微光谱对相同的颗粒缀合物进行了相关研究。单金纳米颗粒和二聚体之间相分辨响应的直接比较突出了四波混频技术在以二聚体作为等离子体尺的传感应用中的前景。
