二維細桿形金屬奈米粒子之表面電漿子現象

Surface plasmon resonances of two-dimensional gold nanoparticles

林德焜(Te-Kun Lin)

指導教授 ： 郭茂坤

國立臺灣大學/工學院/應用力學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.03167

摘要

根據Maxwell電磁理論，探討無限域中二維細桿形金奈米粒子受到磁場在 軸方向極化之平面電磁波與電偶極波源所造成的表面電漿子現象。在多重中心展開法的理論架構下，以多個展開中心展開散射體的散射場及內域場，透過在散射體邊界上取點及滿足邊界條件，並配合奇異值拆解法求得展開係數。
本研究主要探討不同細長比之單、雙顆實心或核-殼細桿形金奈米粒子於電、磁場中受到平面波或電偶極波源時，散射體的表面電漿子現象。由數值結果可以得知，細桿形散射體與橢圓形散射體在相同細長比的條件下，有相似地遠場行為；以及藉由調整核-殼散射體的殼層厚度，可以得到所需的共振波長。最後，我們將利用電偶極波源來模擬一分子所輻射之電磁場；並藉由兩顆實心或核-殼細桿形散射體來模擬光學顯微鏡之探針。

關鍵字

奈米粒子 ； 表面電漿子 ； 多重中心展開法 ； 散射截面積 ； 電偶極 ； 橫電波

並列摘要

Surface plasmon resonances of two-dimensional gold nanoparticles under the electrical dipole source and plane electromagnetic wave(magnetic polarized in z-direction) are investigated. By using Maxwell’s equations and multi-multipole method, a set of linear equations of expansion coefficients is first constructed by satisfying boundary conditions pointwisely. Singular value decomposition is then used to solve the overdetermined linear equations. The far field responses are estimated by calculating the scattering cross section and absorption cross section.
Numerical results of single solid/core-shell and two cylindrical nanorods under plane electromagnetic wave with resonance frequency are presented. It is demonstrated from numerical results that the resonance wavelength of core-shell nanorods strongly depends on the shell thickness. It is also observed that cylindrical nanorod and nanoellipse have similar far field responses on the same slenderness ratio. Finally, we also use electrical dipole source to imitate the electromagnetic field radiated of molecule, and employ two cylindrical solid/core-shell nanorods to replace the detector of microscope.

並列關鍵字

nanoparticle ； surface plasmon ； multi-multipole method ； scattering cross section ； electrical dipole ； TE wave ； substrate ； half-plane ； nanorod

參考文獻

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