College of Science and Technology, Nihon University , Chiyoda, Tokyo 101-8308, Japan.
ACS Nano. 2015 Feb 24;9(2):1895-904. doi: 10.1021/nn506800a. Epub 2015 Feb 2.
We demonstrate that Pd nanospheres exhibit much higher susceptibility of the localized surface plasmon resonance (LSPR) peak to medium refractive index changes than commonly used plasmonic sensing materials such as Au and Ag. The susceptibility of spherical Au nanoparticle-core/Pd-shell nanospheres (Au/PdNSs, ca. 73 nm in diameter) was found to be 4.9 and 2.5 times higher, respectively, than those of Au (AuNSs) and Ag nanospheres (AgNSs) having similar diameters. The experimental finding was theoretically substantiated using the Mie exact solution. We also showed from a quasi-static (QS) approximation framework that the high susceptibility of Pd LSPR originates from the smaller dispersion of the real part of its dielectric function than those of Au and Ag LSPR around the resonant wavelength. We conclude that the Pd nanoparticle is a promising candidate of "the third plasmonic sensing material" following Au and Ag to be used in ultrahigh-sensitive LSPR sensors.
我们证明，钯纳米球比常用的等离子体传感材料如金和银表现出更高的局域表面等离子体共振（LSPR）峰对介质折射率变化的敏感性。球形金纳米核/钯壳纳米球（Au/PdNSs，直径约为 73nm）的敏感性分别比具有相似直径的金（AuNSs）和银纳米球（AgNSs）高 4.9 倍和 2.5 倍。实验结果通过 Mie 精确解进行了理论证实。我们还从准静态（QS）近似框架中表明，钯 LSPR 的高敏感性源于其介电函数实部的分散性小于金和银 LSPR 在共振波长附近的分散性。我们得出结论，钯纳米颗粒是继金和银之后有望成为超灵敏 LSPR 传感器中“第三种等离子体传感材料”的候选材料。
