2011-08-012024-05-16https://scholars.lib.ntu.edu.tw/handle/123456789/666744摘要：在適當波長之光波照射下，金屬奈米粒子表面可產生電漿波動，稱為侷域性表面電漿子。此種表面波動現象常導致極大之局部電場強度，而有許多奈米光子學上的應用。相較於單一金屬奈米粒子，多個或群集之金屬奈米粒子的表面電漿效應更為複雜，有待進一步研究。本計畫擬改進吾人正發展中之簡化邊界積分方程法，以計算金屬奈米粒子群集之電磁場分佈，分析其電磁特性。所謂簡化之邊界積分方程法係指在準靜態近似下，將每一金屬奈米粒子表面分為六個區塊，假設每一區塊上的等效面電流密度與面磁流密度為常數，以減少未知變數之個數。本方法仍大致保有積分方程法的準確性，且適於計算多個散射體的吸收與散射。吾人藉改進之簡化邊界積分方程法計算各種金屬奈米粒子群集的電磁場分佈，以探尋合適之奈米群集，期達到擴大頻寬或調整共振波長之目的。吾人亦變化多個金屬奈米粒子之隨機排列方式，進行掃描波長下的大量數值模擬，計算散射與吸收截面積之波長響應，以探討多個金屬奈米粒子之有效介質常數概念之可行性與限制。<br> Abstract: By illumination of light at a proper wavelength, a surface plasma wave, called the localized surface plasmon, can be induced on the surface of a metallic nanoparticle. The concomitant localized high electric field intensity may lead to applications in nanophotonics. The surface plasmon effect of a cluster of metallic nanoparticles is more complicated than that of a single nanoparticle, and deserves further investigation. In this proposal, we try to improve our developing simplified boundary integral-equation method to numerically compute the electromagnetic field distribution of metallic nanoparticle clusters for investigating their electromagnetc properties. For our simplified boundary integral-equation method, the equivalent surface electric and magnetic current densities on the boundary surfaces are, under the quasi-static approximation, assumed to be constant on each of the six sub-surfaces of each metallic nanoparticle. This method can then reduce the number of unknown variables, but may still take some advantage of the accuracy of an integral-equation method. Therefore, it is suitable for calculating the absorption and scattering of a large number of scatterers. With this improved numerical method, the electromagnetic field distribution of metallic nanoparticle clusters is computed for studying the feasibility of bandwidth broadening and resonance tunability. We also investigate the effect of random arrangement of multiple metallic nanoparticles on the spectra of absorption and scattering cross sections. This may help clarify the availability and limitation of the concept of effective dielectric constant for multiple metallic nanoparticles.金屬奈米粒子群集表面電漿子數值模擬metallic nanoparticleclustersurface plasmonnumerical simulation