Study of surface plasmon resonance for metallic nanoshells

首先，我們將介紹一種不同於混雜理論的等效場理論，特別用來處理金屬球殼粒子。與混雜理論不同的是，這個等效場理論不把自由電子當成自由流體，再以Lagrangian的力學方式去解，而是採用一種等效介質的想法，加上電動力學中的邊界問題的唯一性條件，有系統的求出金屬球殼粒子的極化率，再由此極化率，我們可以得出這個金屬球殼粒子的表面電漿共振波長。 接下來，利用這個等效場理論研究電偶與電偶之間的交互作用，特別是當這一對電偶在靠近金屬球殼時。我們可以觀察到其交互作用會隨著金屬球殼上的表面電漿之鍵結與反鍵結膜態有巨大的加強效果。 最後，利用這樣的等效場理論，我們考慮奈米金屬球殼粒子的混合體，觀察不同的溫度與不同幾合分佈對此混合體的影響。我們發現，有一個特別的共振膜態不受混合體幾何分佈影響，且只出現在金屬球殼粒子中，在實心金屬球中不出現。First of all, we present an approach alternative to the hybridization model for the treatment of the coupled interfacial plasmon modes in metallic nanoshells. Rather than formulating the problem form the Lagrangian dynamics of the free electronic fluid, we adopt an effective medium approach together with the uniqueness of the solutions to electromagnetic boundary value problem, from which the polarizability of the shells can then be systematically and efficiently derived; and the resonance frequencies for the coupled modes can be obtained from the poles in the polarizability. Secondly, by using this effective medium theory we study the modified dipole-dipole interaction between the molecules in the vicinity of a spheroidal metallic nanoshell. From which huge enhancement of the energy transfer rate is obtained due to the resonant excitation of the bounding and anti-bounding plasmonic modes of the nanoshell. Finally, we study the optical properties of a metallic nanoshell composite with particular focus on the effects of variation in temperature and particle clustering on these properties. One unique result from our modeling is the persistent manifestation of the single-particle resonances of the individual nanoshells which cannot be found in a composite of solid particles