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Spectral dependence of fluorescence near plasmon resonant metal nanoparticles.

机译：等离子体共振金属纳米粒子附近荧光的光谱依赖性。

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摘要

The optical properties of fluorophores are significantly modified when placed within the near field (0--100 nm) of plasmon resonant metal nanostructures, due to the competition between increased decay rates and "hotspots" of concentrated electric fields. The decay rates and effective electric field intensities are highly dependent on the relative position of dye and metal and the overlap between plasmon resonance and dye absorption and emission. Understanding these dependencies can greatly improve the performance of biosensing and nanophotonic devices. In this dissertation, the fluorescence intensity of organic dyes and CdSe quantum dots near single metal nanoparticles is studied as a function of the local surface plasmon resonance (LSPR) of the nanoparticle. Single metal nanoparticles have narrow, well-defined, intense local surface plasmon resonances that are tunable across the visible spectrum by changes in size and shape.;First, we show that organic dyes can be self-assembled on single silver nanoprisms into known configurations by the hybridization of thiolated DNA oligomers. We correlate the fluorescence intensity of the dyes to the LSPR of the individual nanoprism to which they are attached. For each of three different organic dyes, we observe a strong correlation between the fluorescence intensity of the dye and the degree of spectral overlap with the plasmon resonance of the nanoparticle. On average, we observe the brightest fluorescence from dyes attached to metal nanoparticles that have a LSPR scattering peak 40--120 meV higher in energy than the emission peak of the fluorophore.;Second, the plasmon-enhanced fluorescence from CdSe/CdS/CdZnS/ZnS core/shell quantum dots is studied near a variety of silver and gold nanoparticles. With single-particle scattering spectroscopy, the localized surface plasmon resonance spectra of single metal nanoparticles is correlated with the photoluminescence excitation (PLE) spectra of the nearby quantum dots. The PLE spectra closely track the scattering spectra of the metal nanoparticles. By taking advantage of the ability to excite quantum dots across a wide range of wavelengths while detecting a single emission wavelength, we measure an excitation enhancement factor for single metal nanoparticles. The data also provide a calculation of a lower-bound of experimentally attainable enhancement factors solely due to increased near-field excitation. This factor was found to range from ∼3 to 10 for Au spheres, Ag cubes and Ag nanoprisms.
机译：当放置在等离振子共振金属纳米结构的近场（0--100 nm）中时，由于增加的衰减率和集中电场的“热点”之间的竞争，荧光团的光学性质会显着改变。衰减率和有效电场强度高度依赖于染料和金属的相对位置以及等离激元共振与染料吸收和发射之间的重叠。了解这些依赖性可以大大提高生物传感和纳米光子设备的性能。本文研究了单金属纳米粒子附近有机染料和CdSe量子点的荧光强度与纳米粒子的局部表面等离子体共振（LSPR）的关系。单一金属纳米粒子具有狭窄，界限分明，强烈的局部表面等离子体共振，可通过尺寸和形状的变化在可见光谱范围内调节。首先，我们证明有机染料可以在单个银纳米棱镜上自组装成已知构型，具体方法如下：硫醇化DNA低聚物的杂交。我们将染料的荧光强度与它们所附着的单个纳米棱镜的LSPR相关联。对于三种不同的有机染料，我们观察到染料的荧光强度与光谱重叠程度与纳米粒子的等离子体共振之间有很强的相关性。平均而言，我们观察到附着在金属纳米粒子上的染料发出的最亮荧光，其能量的LSPR散射峰比荧光团的发射峰高40--120 meV;第二，来自CdSe / CdS / CdZnS的等离激元增强荧光/ ZnS核/壳量子点是在各种银和金纳米粒子附近研究的。使用单粒子散射光谱法，单金属纳米粒子的局部表面等离子体共振光谱与附近量子点的光致发光激发（PLE）光谱相关。 PLE光谱紧密跟踪金属纳米颗粒的散射光谱。通过利用在宽波长范围内激发量子点的能力，同时检测单个发射波长，我们可以测量单个金属纳米粒子的激发增强因子。数据还提供了仅由于增加的近场激励而在实验上可获得的增强因子的下限的计算。对于金球，Ag立方体和Ag纳米棱镜，发现该因子的范围约为3至10。

著录项

  • 作者

    Chen, Yeechi.;

  • 作者单位

    University of Washington.;

  • 授予单位 University of Washington.;
  • 学科 Chemistry Physical.;Physics Condensed Matter.;Physics Optics.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 91 p.
  • 总页数 91
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 物理化学（理论化学）、化学物理学;光学;
  • 关键词

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