表面等離子共振 (SPR) 是受激發的電子的總體振動，一般在金屬、電介質界面上發生。我們能以振盪的電場去激發SPR。由於表面等離子共振時會產生巨大的增強電場，這令他在近場光學與納米光學中有著廣泛的應用。例如：微流控芯片、等離子波導、隱形裝置等等。 / 在這論文中，我們會研究納米金屬體之間的作用力。基於以下原因，這在納米技術中是一個重要課題。第一，當了解到物體之間的作用力後，我們可以以此開發出把納米尺寸的物體移動與放置的方法，有助於用自下而上式的方法製作納米器件。第二，物體之間的作用力會改變器件中納米顆粒的位置，因而會影響器件的特性。 / 在一般情況下，納米尺寸的物體的作用力都可以略去不理的，因為作用力是與體積成正比。但是，當表面等離子共振發生時，相互作用力會急速地增強。這增強是由於金屬顆粒的電偶會急速地增強的原故。我們稱這現象為「表面等離子共振增強光泳」 (SPREP). / 這論文由三個主要部份組成。第一部份，我們研究一帶梯度的金屬納米球與一振盪及旋進電偶之間的相互作用。我們以第一原理進路去解決這問題，並作了長波長假設。我們的解析解能夠處理多極效應，這效應在外場不均勻時是不可忽略的。我們探討了作用力、力矩、電場分佈。更發現了，當金屬納米球的梯度很高時，電偶與金屬納米球之間與有一穩定的力平衡。這研究有助於開發新型的光學鑷子。 / 第二部份，我們探討兩個金屬納米球之間的 SPREP，我們介紹了不同的計算方法。Bergman-Milton譜表示以及多重鏡象法。 兩個金屬納米球之間也有著穩定的平衡， 這表示在一群納米球中，可能有著穩定結構。這穩定的平衡，是由於表面等離子共振的頻率與相互距離有關，這是一種多體效應。這研究有助於了解納米簇的結構形成。 / 最後，我們以離散偶極子近似法(DDA)研究多體問題，雖然DDA並不是精確解，但當顆粒之間相距不太接近時，這依然是一個良好的近似。當顆粒的數量太多時，我們以等效介質理論去著手，不再考慮每一顆粒各自的位置，而只考慮顆粒的濃度。 / Surface plasmon resonance (SPR) is the collective electrons excitations, which occurred at the metal-dielectric interfaces and can be induced by an oscillating electric field. Because of the large field enhancement, SPR has a wide range of applications in near field optics and nano-optics, such as biosensors, lab-ona- chip devices, plasmonic waveguides, and cloaking devices. / In this thesis, we study the interparticle forces between metallic nanosized objects. It is an important topic in nanotechnology for at least two reasons. Firstly, the study of the interparticle forces may provide methods to control the motion and position of nano-size objects, which can be used to fabricate artificial nano-structure by bottom up approach. Secondly, the force can change the arrangement of the particles in the nanodevices and hence affecting the property of the devices. / The interparticle forces of nano-sized dielectric particles are negligible, since the force is proportional to the volume of the objects. However, the interparticle forces of metallic particles will be greatly enhanced when SPR occurs, which is able to compensate the volume effect. This phenomenon is called surface plasmon resonance enhanced photophoresis (SPREP), which is one of the consequences of the rapid increase in the dipole moment in the particles. / This thesis is consisted of three main parts. In the first part, we study the SPREP between a graded metallic nanosphere and a point dipole which is undergo oscillation and precession. A first principle approach is applied to handle this problem. Our analytic solutions are able to capture the multipole effect, which cannot be neglected in highly non-uniform fields. We have analyzed three important physical quantities: the induced force, the induced torque, and the field distribution. Furthermore, we find that there is a binding between the nanoparticle and the dipole source, when the gradation of the graded particles is large enough. This study has a potential application in developing a novel kind optical tweezers. / In the second part, we study the SPREP between two metallic nanoparticles. The force spectra are calculated by two different methods: Bergman- Milton spectral representation and multiple image method. The binding between two nanoparticles is observed, which indicates a possible stable structure among the metallic clusters. The binding is caused by the excitation of collective plasmon modes, and the consequence that the resonance poles sℓ are the functions of separation distances. This study may provide a better understanding in the structure formation of colloidal clusters in nano-scales. / Finally, we consider a many-particle system by the discrete dipole approximation (DDA) and effective medium theory. Although, the DDA is not an exact formalism, it is a suitable approximation for considering finite number of particles, if the distances among particles are not too close. When the number of particles in the host solution is large, we can use the effective medium theory to handle the problem. Instead of considering all discrete particles individually, we will consider the interaction between a single particle and a new effective host solution, where the dielectric function of the effective host solution is determined by the concentration of nanoparticles in the host solution. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Kin Lok = 納米金屬顆粒中的表面等離子共振增強光泳 / 陳建樂. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 90-94). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Chan, Kin Lok = Na mi jin shu ke li zhong de biao mian deng li zi gong zhen zeng qiang guang yong / Chen Jianle. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Nanoparticles and nanotechnology --- p.1 / Chapter 1.2 --- The history of nanoparticles and nano-optics --- p.1 / Chapter 1.3 --- Applications of nanoparticles --- p.2 / Chapter 1.3.1 --- Optical applications --- p.2 / Chapter 1.3.2 --- Biological and medical applications --- p.3 / Chapter 1.4 --- Electrokinetics of nanoparticles --- p.4 / Chapter 1.4.1 --- Review on recent work on electrokinetics --- p.5 / Chapter 1.5 --- Objectives of the thesis --- p.6 / Chapter 2 --- Basic Principles --- p.8 / Chapter 2.1 --- Drude model --- p.8 / Chapter 2.2 --- Complex dielectric function --- p.9 / Chapter 2.2.1 --- Electric field in an imperfect conductor --- p.10 / Chapter 2.3 --- Effective medium theory --- p.11 / Chapter 2.3.1 --- Maxwell-Garnett approximation --- p.12 / Chapter 2.3.2 --- Bruggeman approximation --- p.13 / Chapter 2.3.3 --- Bergman-Milton spectral representation (BMSR) --- p.13 / Chapter 2.3.4 --- Effective dielectric function of shelled sphere --- p.17 / Chapter 2.4 --- Surface plasmon resonance (SPR) --- p.18 / Chapter 2.5 --- Surface plasmon resonance enhanced photophoresis (SPREP) --- p.20 / Chapter 2.6 --- Justification of long wavelength limit --- p.23 / Chapter 3 --- Manipulation of Nanoparticles by a Single Dipole Source --- p.25 / Chapter 3.1 --- Introduction --- p.25 / Chapter 3.2 --- Formalism --- p.26 / Chapter 3.2.1 --- Electrostatic potential of a dipole --- p.27 / Chapter 3.2.2 --- Electrostatic potential of a dipole in terms of multipole expansion --- p.27 / Chapter 3.2.3 --- Laplace's equation of graded sphere --- p.30 / Chapter 3.2.4 --- Boundary value problem --- p.31 / Chapter 3.2.5 --- Force --- p.33 / Chapter 3.2.6 --- Torque --- p.35 / Chapter 3.3 --- Result and discussion --- p.36 / Chapter 3.3.1 --- Force --- p.38 / Chapter 3.3.2 --- Torque --- p.45 / Chapter 3.3.3 --- Electric field distribution --- p.46 / Chapter 3.4 --- Conclusion --- p.48 / Chapter 4 --- Interaction between Two Objects --- p.49 / Chapter 4.1 --- Introduction --- p.49 / Chapter 4.2 --- Interaction between two particles --- p.50 / Chapter 4.2.1 --- Dipole approximation --- p.50 / Chapter 4.2.2 --- Multiple images method --- p.52 / Chapter 4.2.3 --- Bergman-Milton spectral representation for collection of grains --- p.58 / Chapter 4.2.4 --- Equation of motion --- p.61 / Chapter 4.2.5 --- Result and discussion --- p.62 / Chapter 4.3 --- Particle near a conducting plane --- p.67 / Chapter 4.3.1 --- Dipole approximation --- p.67 / Chapter 4.3.2 --- Multiple image method --- p.69 / Chapter 4.3.3 --- Result and discussion --- p.70 / Chapter 5 --- Many-particle Systems --- p.72 / Chapter 5.1 --- Introduction --- p.72 / Chapter 5.2 --- Discrete dipole approximation --- p.72 / Chapter 5.2.1 --- 2-particle system --- p.73 / Chapter 5.2.2 --- 4-particle system --- p.74 / Chapter 5.2.3 --- Result and discussion --- p.75 / Chapter 6 --- Concentration Effect --- p.80 / Chapter 6.1 --- Introduction --- p.80 / Chapter 6.2 --- Formalism --- p.81 / Chapter 6.2.1 --- Result and discussion --- p.83 / Chapter 7 --- Summary --- p.88 / Bibliography --- p.90 / Chapter A --- Eigenfunctions, Eigenvalues, and Green's function --- p.95 / Chapter A.1 --- Isolated sphere --- p.95 / Chapter A.1.1 --- Eigenfunctions and eigenvalues --- p.96 / Chapter A.1.2 --- Green's function --- p.98 / Chapter A.2 --- Planar interface --- p.98 / Chapter A.2.1 --- Eigenfunctions and eigenvalues --- p.99 / Chapter A.2.2 --- Green's function --- p.100 / Chapter B --- Property of Spherical Harmonics and Associated Legendre Polynomials --- p.101 / Chapter B.1 --- Complex conjugate of Yℓm(Ω): --- p.102 / Chapter B.2 --- Differential Property --- p.102 / Chapter B.3 --- Limiting value --- p.102
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_327984 |
| Date | January 2012 |
| Contributors | Chan, Kin Lok., Chinese University of Hong Kong Graduate School. Division of Physics. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (xiii, 103 leaves) : ill. (some col.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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