Gold Nanoframes: Very High Surface Plasmon Fields and Excellent Near-Infrared Sensors
Gold Nanoframes: Very High Surface Plasmon Fields and Excellent Near-Infrared Sensors
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DOI：
10.1021/ja104532z
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发表时间：
2010-09-15
影响因子：
15
通讯作者：
El-Sayed, Mostafa A.
中科院分区：
文献类型：
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作者：
Mahmoud, Mahmoud A.;El-Sayed, Mostafa A.
贵金属纳米颗粒的感测效率或因子被定义为周围介质的折射率的每单位变化的表面等离子体共振消光峰位置的波长偏移。许多研究者已经研究了不同形状和尺寸的金纳米颗粒的灵敏度，并发现其取决于等离子体场强度。其结果是，灵敏度因子被发现是更大的空心纳米粒子比固体的可比尺寸。这是由于中空纳米颗粒中的外表面等离子体场和内表面等离子体场之间的耦合产生的强等离子体场。在本文中，大量的不同尺寸和壁厚的金纳米框架的灵敏度因子已被确定通过实验和理论计算（使用离散偶极子近似方法）。的灵敏度因子和等离子体激元场强度的壁厚和尺寸的纳米框架的依赖关系已被确定和讨论。的灵敏度因子被发现与纳米框架的纵横比（壁长/壁厚）线性增加，特别是在壁厚的减少敏感。与其他等离子体纳米粒子相比，发现纳米框架的灵敏度因子分别比金纳米球、金纳米立方体和金纳米棒的灵敏度因子高12、7和3倍，并且比可比尺寸的金纳米笼的灵敏度因子高几百个单位。
The sensing efficiency or factor of noble metal nanoparticles is defined as the wavelength shift of the surface plasmon resonance extinction peak position per unit change in the refractive index of the surrounding medium. The sensitivity of different shapes and sizes of gold nanoparticles has been studied by many investigators and found to depend on the plasmon field strength. As a result, the sensitivity factors were found to be larger for hollow nanoparticles than for solid ones of comparable dimensions. This is due to the strong plasmonic fields resulting from the coupling between the external and internal surface plasmon fields in the hollow nanoparticles. In the present paper, the sensitivity factors of a large number of gold nanoframes of different size and wall thickness have been determined by experimental and theoretical computation (using the discrete dipole approximation method). The dependence of the sensitivity factors and the plasmon field strength on the wall thickness and the size of the nanoframes has been determined and is discussed. The sensitivity factors are found to increase linearly with the aspect ratio (wall length/wall thickness) of the nanoframes and are especially sensitive to a decrease in the wall thickness. In comparison with other plasmonic nanoparticles, it is found that nanoframes have sensitivity factors that are 12, 7, and 3 times higher than those of gold nanospheres, gold nanocubes, and gold nanorods, respectively, as well as more than several hundred units higher than those of comparable-size gold nanocages.