金屬奈米結構對螢光增益之研究

Abstract

本研究根據Maxwell電磁理論，探討三維金、銀奈米粒子與可見光波交互作用的現象。研究方法使用多重中心展開法，以多個展開中心展開散射體之散射場及內域場，透過在散射體邊界上取點及滿足邊界條件以建立一係數矩陣方程組，並以奇異值拆解法求解矩陣。 研究內容包含入射平面電磁波激發奈米粒子的表面電漿共振，並利用產生的局部電場激發螢光分子，計算此分子處的激發效率；此分子達激發態以後，利用一電偶極波源模擬此螢光的輻射場，並與奈米粒子作用後，研究其產生的螢光增益效果。 本研究探討了橢球、核殼球形、核殼橢球、圓柱以及圓盤形狀奈米粒子的螢光增益效果，並仔細整理出這些結構下能達到最好的螢光增益效果。

In this paper, we study the three-dimensional gold and silver nanoparticles interacting with visible light by using Maxwell`s equations. The multiple-multipole (MMP) method is employed to construct a set of linear equations of expansion coefficients by satisfying boundary conditions at collocation points. Singular value decomposition is then used to solve the overdetermined linear equations. The study includes the electric field in the vicinity of a metallic nanostructure which is dramatically intensified through surface plasmon resonances (SPR) effect by incident plane wave, and it is useful for exciting nearby fluorescent molecules. Once the molecule is excited, it behaves as an electric dipole to radiate the fluorescence and interacts with nanoparticles. The overall effect of nanoparticles on the fluorescence will be studied by evaluating the enhancement factor. We study several metallic nanostructures for enhancing the fluorescence enhancement including nanospheroids, nanoshells, core-shell nanospheroids, nanorods, and nanodisks. And classify the benefit of each structure in the conclusion.