College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, 410082, P R China.
Anal Chem. 2013 Apr 2;85(7):3789-93. doi: 10.1021/ac400240v. Epub 2013 Mar 14.
The enhancement of the electromagnetic field on the rough metallic nanostructure has been extensively applied to obtain chemical or biological information about molecules with high sensitivity and has received much attention due to its potential applications in new types of devices based on nanoelectronics and nanophotonics. The typical size of the field enhancement area, the so-called hotspot, is approximately 1 order of magnitude smaller than the optical diffraction limit. In the present study, an optical super-resolution microscopic and spectroscopic approach is introduced to explore single-molecule fluorescence within a hotspot where nonhomogeneous spectral modulation is resolved beyond the optical diffraction limit for the first time. Distinct Stokes shifts from individual dyes were directly observed within single hotspots, which were found to be independent of the local electromagnetic field strength. The method reported here provides a robust tool to probe the optical properties of nanoresonantors with high temporal and spatial resolution.
粗糙金属纳米结构上的电磁场增强已被广泛应用于获得具有高灵敏度的化学或生物分子信息，并且由于其在基于纳米电子学和纳米光子学的新型器件中的潜在应用而受到了广泛关注。典型的场增强区域大小，即所谓的热点，大约比光学衍射极限小 1 个数量级。在本研究中，引入了一种光学超分辨率显微和光谱方法，首次在热点内探索单分子荧光，其中非均匀光谱调制超过了光学衍射极限。在单个热点内直接观察到来自各个染料的明显斯托克斯位移，发现它们与局部电磁场强度无关。这里报道的方法提供了一种强大的工具，用于以高时空分辨率探测纳米共振器的光学性质。
