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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A biophysical study of the G protein coupled receptor neurotensin receptor 1

Harding, Peter J. January 2007 (has links)
Neurotensin (NT) is a tridecapeptide neurotransmitter found in the central nervous system and gastrointestinal tract. Neurotensin receptor 1 (NTS1), a high affinity receptor for NT, is a member of the GPCR superfamily and is a putative target for the treatment of conditions such as Schizophrenia, Parkinson’s Disease and drug addiction. Overexpression and purification are typically limiting steps in the high resolution structure determination of GPCRs. In this study, through the optimisation of the E.coli strain used for overexpression of rat NTS1 (NTS1) and the inclusion of phospholipids in the purification buffers to prevent delipidation, an approximate 3-fold improvement in active receptor yield was obtained relative to existing protocols. Preliminary electron microscopy (negative stain and cryo) confirmed a monodisperse receptor population. Purified NTS1 is now being produced at a sufficient level for high resolution structural studies, including 3D crystallisation and further electron microscopy studies. The existing construct for the expression of NTS1 in E.coli, termed NTS1B, was modified to contain a fusion to the genes encoding either the eCFP or eYFP fluorescent proteins. These constructs were used for the E.coli expression of NTS1 tagged with either fluorescent protein at the C-terminus. Tagged receptor was successfully expressed at levels of up to 0.29 ± 0.03 mg per l of culture. Successful purification and proteolytic removal of the MBP and TrxA-His10 fusion partners was achieved whilst retaining both fluorescence and ligand binding capability (K<sub>d</sub> = 0.91 ± 0.17 nM). Purified, fluorescent receptor was reconstituted into brain polar lipid (BPL) liposomes in an active conformation which was both fluorescent and able to bind NT. Experimentation with alternative lipid compositions suggested that specific lipids are required in order to maintain ligand-binding activity. FRET between the eCFP- and eYFP-tagged receptors was observed in reconstituted samples. The FRET efficiency was comparable to that observed in vivo for other GPCRs, including the yeast α-factor receptor, which is believed to be dimeric. This suggests that NTS1 could also be multimeric. In contrast, no FRET was observed in detergent samples. Therefore, a functioning in vitro system has been developed which enables the study of NTS1 multimerisation in lipid bilayers and future studies will attempt to implement single molecule fluorescence techniques. In addition, fluorescent derivatives of NT were successfully synthesised and purified. Radioligand competition assays and fluorescence correlation spectroscopy (FCS) confirmed that the fluorescent peptides bound to purified NTS1 in specific competition with unlabelled NT. Surface plasmon resonance (SPR) was used to confirm the ligand binding activity of purified NTS1. A novel approach was utilised which involved the measurement of the binding of detergent-solubilised NTS1 to immobilised, N-terminally biotinylated NT on the sensor surface. The use of a rigorous control, which consisted of immobilised ‘scrambled sequence’ NT, demonstrated a specific interaction. Analysis of the kinetics revealed a multiphasic interaction with a K<sub>d</sub> in the nanomolar range. In summary, improvements to the expression and purification of NTS1, the generation of fluorescent constructs as useful tools in the study of receptor multimerisation and the optimisation of lipid-reconstitution protocols have opened up several preliminary lines of study which show considerable potential for future research.
32

Radiative decay and coupling of surface plasmons on metallic nanohole arrays. / 表面等離子體在金屬納米孔陣列的輻射衰減及耦合 / Radiative decay and coupling of surface plasmons on metallic nanohole arrays. / Biao mian deng li zi ti zai jin shu na mi kong zhen lie de fu she shuai jian ji ou he

January 2013 (has links)
了解表面等子體和外部環境之間的相互作用對表面等子體應用的開發非常重要。我們的研究集中在表面等子體與遠場的耦合,以及表面等子體模之間的耦合。 / 首先,我們研究由表面等子體模式耦合所產生的射衰變的變化。我們以角分辨反射光譜測同孔大小的納米孔陣上的簡併表面等子體模的衰減。對於每個孔的大小,我們觀察到在發生共振耦合的光譜區,衰減速有很大的改變,顯示出暗模和模的形成。耦合模很好地解釋衰變的變化。推導出的耦合常隨著孔直徑的增加而增加。我們也對耦合模一些有趣的特性及衰減變化的微觀起源進探討。 / 第二,我們以偏振分辨反射光譜從二維屬陣射散射。我們發現,反射光譜遵循的法模型可以由耦合模和瓊斯矩陣演算推導出。通過用正交方向的偏光器和分析器,反射光譜上的谷翻轉成峰,從以能夠測定出射散射效。我們發現,射散射效與波長和孔直徑的依賴關係和單孔的瑞散射相符合。 / 最後,我們開發一個新的方法,以偏振分辨光譜在實驗中測射衰變。這方法的有效性通過時域有限差分計算得到證明。我們還將此方法應用在實驗據上作為示範。 / Understanding the interaction between surface plasmon and outer environment is crucial in development of plasmonic applications. Our study is focused on the coupling between surface plasmons and far field, and also the coupling between surface plasmon modes. / First, we studied the change in radiative decay rate due to coupling of degenerate surface plasmon modes. We measured the decay rates of two degenerate surface plasmon modes in Au nanohole arrays with different hole sizes by angle-resolved reflectivity spectroscopy. For each hole size, at the spectral region where resonant coupling occurs, we observed a large modification in decay rates, leading to the formation of dark and bright modes. The change in decay rates is well explained by coupled-mode theory. The deduced coupling constant is found to increase with increasing hole diameter. Interesting properties of the coupled modes and microscopic origin of the change in decay rate is also discussed. / Second, we measured the radiative scattering from two-dimensional metallic arrays by using polarization-resolved reflectivity spectroscopy. We found that the reflectivity spectra follow the Fano-like model which can be derived from coupled-mode theory and Jones matrix calculus. By orthogonally orienting the incident polarizer and the detection analyzer, reflectivity dips flip into peaks and the radiative scattering efficiency can be determined accordingly. The dependence of total radiative scattering efficiency on wavelength and hole diameter is found to agree well with Rayleigh scattering by single hole. / Finally, we developed a new method to measure radiative decay rates experimentally by polarization-resolved reflectivity spectroscopy. The validity of this method is proved by finite-difference time-domain simulation. We also applied this method on experimental data as a demonstration. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lo, Hau Yung = 表面等離子體在金屬納米孔陣列的輻射衰減及耦合 / 羅孝勇. / "December 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 88-92). / Abstracts also in Chinese. / Lo, Hau Yung = Biao mian deng li zi ti zai jin shu na mi kong zhen lie de fu she shuai jian ji ou he / Luo Xiaoyong. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Basic Theory and Techniques --- p.3 / Chapter 2.1 --- Macroscopic Maxwell Equations and Boundary Conditions --- p.3 / Chapter 2.2 --- Symmetries and Band Structure --- p.4 / Chapter 2.3 --- Coupled-mode Theory --- p.10 / Chapter 2.4 --- Finite-difference Time-domain Simulation --- p.12 / Chapter 2.5 --- Preparation of Metallic Nano-hole Arrays --- p.14 / Chapter 3 --- Fundamentals of Surface Plasmons on Metallic Nanohole Array --- p.18 / Chapter 3.1 --- Confinement and Propagation Nature of SPs --- p.18 / Chapter 3.2 --- Skin Depth and Propagation Length --- p.19 / Chapter 3.3 --- Dispersion Relation and Phase-matching Conditions --- p.21 / Chapter 3.4 --- Measurement of Band Structure: Angle-resolved Reflectivity Mapping --- p.23 / Chapter 3.5 --- Red Shift of Band Structure --- p.26 / Chapter 3.6 --- Comparison of Two Presentations of Band Structure: "ω against k" versus "λ against θ" --- p.28 / Chapter 3.7 --- Resonance Peak Shape: FanoModel and Wood's Anomalus --- p.30 / Chapter 3.8 --- Resonance Peak Shape: "Fano-like" Model --- p.34 / Chapter 3.9 --- Appendix A: Derivation of Eq(3.1) --- p.36 / Chapter 4 --- Decay Rates Modification though Coupling of Degenerate Surface Plasmon modes --- p.40 / Chapter 4.1 --- Introduction --- p.40 / Chapter 4.2 --- Measurements of Degenerate Surface Plasmon Modes --- p.42 / Chapter 4.3 --- Decay rates of Coupled Modes --- p.45 / Chapter 4.4 --- Hole Diameter Dependence of Coupling Constants --- p.47 / Chapter 4.5 --- Understanding the S-polarized Surface Plasmon Modes --- p.50 / Chapter 4.6 --- TE-like Surface Plasmon Modes --- p.53 / Chapter 4.7 --- Microscopic Origin of the Modification in Decay Rate --- p.54 / Chapter 4.8 --- Summary --- p.60 / Chapter 5 --- Direct Measurement of Radiative Scattering of Surface Plasmon Resonance from Metallic Arrays by Polarization-resolved Reflectivity Spectroscopy --- p.61 / Chapter 5.1 --- Introduction --- p.61 / Chapter 5.2 --- Theory of Direct Measurement of Radiative Scattering --- p.62 / Chapter 5.3 --- Comparison with Experiment --- p.65 / Chapter 5.4 --- Comparison with Rayleigh Scattering Model --- p.71 / Chapter 5.5 --- Summary --- p.74 / Chapter 6 --- A Method of Obtaining Radiative Decay Rates From Experiment --- p.76 / Chapter 6.1 --- Introduction --- p.76 / Chapter 6.2 --- Method --- p.77 / Chapter 6.3 --- Prove of Validity --- p.78 / Chapter 6.4 --- Experimental Demonstration --- p.82 / Chapter 6.5 --- Summary --- p.85 / Chapter 7 --- Conclusion --- p.86 / Chapter 8 --- Bibliography --- p.88 / Chapter 9 --- Curriculum Vitae --- p.93
33

Phase detection techniques for surface plasmon resonance sensors. / CUHK electronic theses & dissertations collection

January 2011 (has links)
In addition, this project also investigated schemes that might enhance the phase change in the SPR sensor. The "double-pass" and "multi-pass" approaches through which the SPR phase can be amplified upon hitting the sensor surface more than once, have been experimentally studied and successfully demonstrated. A double-pass method can immediately offer two times of phase change as compared to the singlepass one. Accordingly the multi-pass scheme offers a higher then two times phase enhancement. Such improvement in phase detection is extremely important for biosensing applications involving small molecules, small proteins, DNA and etc. Another approach for detection performance improvement is to incorporate a multilayer configuration for the biosensing surface. In order to improve the dynamic measurement response, we proposed to use a multiple resonant angle measurement approach in conjunction with the single-beam self-referenced phase-sensitive SPR configuration. With the use of many multiple incident angles, the system provided sensing capability that covers a refractive index (RI) 1.33 to over 1.38. A 128-element array detector was employed to measure the resonance phase change over the range of the incident angles to ensure a reasonably continuous phase response curves achievable from the system. / This project is concerned with the development and optimization of optical sensors based on measuring the phase change of surface plasmon resonance (SPR) effect. The phase sensitive SPR technique provides very high sensitivity performance due to the fact that an abrupt phase jump occurs near the resonance dip, thus resulting in large phase shift with very small change in the sensing medium. A range of different measurement techniques for enhancing system sensitivity have been investigated. Moreover we also studied the phase change characteristics around the SPR dip region by means of simulation in order to explore various approaches for achieving further improvement in sensitivity and as well as wide dynamic range. Since SPR is caused by electron charge density oscillations in metal surface in which the wave momentum required for plasmon wave excitation is always larger than that for free space, an inverted prism-coupling scheme (prism-metal-dielectric) is commonly used and this configuration was also employed in our experimental setup, particularly for the SPR biosensor based on differential phase Mach-Zehnder interferometer configuration. This design primarily operates by taking advantage of the fact that SPR only affects the p-polarization while leaving the s-polarization unchanged. This means that differential phase measurement between the p- and s- polarizations will result in SPR signals that are completely free from any disturbances that are common to both channels. Experimental results obtained from glycerin/water mixtures indicate that the sensitivity limit of our scheme is 5.48 x 10 -8 refractive index unit per 0.01&deg; phase change. To our knowledge, this is a significant improvement over previously obtained results when gold is used as the sensor surface. While acknowledging that accurate optical alignment is a crucial requirement for the Mach-Zehnder interferometer and it is often not easy to maintain high degree alignment accuracies in practical situations, we have developed a versatile and low cost single-beam self-referenced phase-sensitive surface SPR sensing system. The system exhibits a root-mean-square phase fluctuation of +/-0.0028&deg; over a period of 45 minutes, i.e. a resolution of +/-5.2x10 -9 refractive index units. The enhanced performance has been achieved through the incorporation of three design elements: (i) a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected; (ii) a differential measurement scheme to eliminate spurious signals not related to the sensor response; (iii) elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulator. Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional florescence-based techniques. / Wu, Shu Yuen. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 132-147). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
34

Surface plasmon resonance enhanced photophoresis in nano-metallic colloids. / CUHK electronic theses & dissertations collection / Surface plasmon resonance enhanced photophoresis in nano-metallic colloids.

January 2012 (has links)
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
35

Surface plasmon polaritons (SPPs) mediated light extraction efficiency of light-emitting material from metallic nanohole array. / 表面等離子體激元改變納米金屬洞陣列上發光材料的光提取效率 / Surface plasmon polaritons (SPPs) mediated light extraction efficiency of light-emitting material from metallic nanohole array. / Biao mian deng li zi ti ji yuan gai bian na mi jin shu dong zhen lie shang fa guang cai liao de guang ti qu xiao lu

January 2012 (has links)
表面等離子體激元和熒光分子之間的電磁相互作用已因廣泛應用於量子運算中的量子信息處理和分子生物技術的分子檢測而得到相當大的關注。雖然通過把熒光分子放置在電漿系統旁來改善熒光分子的發光度和方向性已被廣泛接受,但是了解表面等離子體激元和熒光材料之間的相互作用的物理亦是很重要的。 / 在這篇論文中,我們將研究在二維納米銀洞陣列上有機染料帶方向性的發光特性。通過量度在每個角度的反射和熒光發光光譜,我們可以繪製出二維納米銀洞陣列所產生的電磁共振模式的色散關係及熒光材料發光度與方向的關係。此外,在陣列上以不同方向行走的表面等離子體激元的衰變壽命亦被找出。我們亦將反射率和熒光發光光譜進行比較,從而發現熒光發光的加強跟表面等離子體激元的光譜位置、衰變後傳播的方向、它的衰變壽命和它的耦合效率有十分密切的關係。為了解背後的物理,我們建立了一個理論模型去區分能量從有機染料轉移到表面等離子體激元的過程與表面等離子體激元衰變過程對表面等離子體激元改變熒光材料發光度的影響。因此,我們可以對能量從有機染料轉移到表面等離子體激元的過程與方向的關係進行定量分析。最後,我們的研究結果與由有限差分時域模擬計算所得的結果吻合。結論得出在二維納米銀洞陣列上所實現的表面等離子體激元増加有機染料光提取效率與三維空間中方向的關係是源於電漿帶隙的產生所引致的態密度重整及分配。 / The electromagnetic interaction between surface plasmon polaritons (SPPs) and fluorescent molecules has been capturing considerable attention for a wide variety of applications ranging from quantum information processing in quantum computing to molecule detection in biotechnology. Although it is widely accepted that the light emission efficiency and directionality are improved by placing the fluorescent molecules in close proximity to a plasmonic system, the understanding of the physics on how SPPs interact with the fluorescent materials is of importance. / In this thesis, the directional emission properties of LDS organic dyes supported on two-dimensional Ag nanohole array is studied. Angle-resolved reflectivity and photoluminescence spectroscopy have been employed to map out the dispersion relations of electromagnetic resonance modes arising from the array and the dependence of plasmonic emission on emission angle. In addition, the decay lifetimes of SPP modes in different propagation directions in array have been determined. By comparing the reflectivity and photoluminescence mappings, we find that the emission enhancement is strongly correlated with the spectral and angular positions of SPP modes together with their lifetimes and coupling efficiencies. To understand the underlying physics, we have developed an analytical model to differentiate the surface plasmon mediated emission (SPME) into energy transfer from LDS to SPPs and the radiative decay of surface plasmons. As a result, the directional dependence of the energy transfer process can then be analyzed quantitatively. Finally, our results are compared with the finite-difference-time-domain simulations with good agreement. It is concluded that the directional dependence of the surface plasmon mediated emission is attributed to the redistribution of the density of states in the periodic nanohole array due to the opening of the plasmonic gaps. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Kay Fung = 表面等離子體激元改變納米金屬洞陣列上發光材料的光提取效率 / 陳其鋒. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 115-123). / Abstracts also in Chinese. / Chan, Kay Fung = Biao mian deng li zi ti ji yuan gai bian na mi jin shu dong zhen lie shang fa guang cai liao de guang ti qu xiao lu / Chen Qifeng. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Surface plasmon polaritons (SPPs) and surface plasmon mediated emission (SPME) --- p.2 / Chapter 1.2 --- Directional surface plasmon mediated emission (SPME) on metallic nanohole array --- p.5 / Chapter 1.3 --- Our analytical model of surface plasmon mediated emission --- p.8 / Chapter 1.3.1 --- Formalism of rate equations --- p.8 / Chapter 1.3.2 --- Determination of the directional dependence of the coupling efficiency from decay rates of the SPP and the fluorescent material --- p.11 / Chapter 1.4 --- Organization of the thesis --- p.12 / Chapter Chapter 2 --- Theory of surface plasmon polaritons --- p.14 / Chapter 2.1 --- The Maxwell’s equations and the boundary conditions for electromagnetic waves --- p.14 / Chapter 2.2 --- Dielectric constant of metal --- p.18 / Chapter 2.3 --- Master equation for electromagnetic waves, the Bloch form of SPPs and the dispersion relation of SPPs at the interface between dielectric and metal --- p.19 / Chapter 2.4 --- Excitation of surface plasmon polaritons by grating coupling --- p.27 / Chapter 2.5 --- Decay of surface plasmon polaritons --- p.29 / Chapter 2.5.1 --- Non-radiative decay --- p.29 / Chapter 2.5.2 --- Radiative decay --- p.31 / Chapter Chapter 3 --- Experimentation and Simulation --- p.37 / Chapter 3.1 --- Sample preparation --- p.37 / Chapter 3.1.1 --- Interference lithography [2.2, 3.7, 3.8] --- p.37 / Chapter 3.1.2 --- E-beam evaporation --- p.39 / Chapter 3.1.3 --- Spin coating of florescence material --- p.40 / Chapter 3.2 --- Measurements --- p.41 / Chapter 3.2.1 --- Angle-resolved specular reflection measurement [3.10] --- p.42 / Chapter 3.2.2 --- Angle-resolved photoluminescence (PL) spectroscopy [3.11] --- p.43 / Chapter 3.2.3 --- K-space (Fourier space) imaging [3.12, 3.13, 3.14] --- p.44 / Chapter 3.3 --- FDTD --- p.46 / Chapter 3.3.1 --- Theory of FDTD --- p.46 / Chapter 3.3.2 --- Simulation of the reflectivity of plane wave --- p.52 / Chapter 3.3.3 --- Simulation of the field pattern with a dipole source --- p.55 / Chapter 3.3.3.1 --- Near-to-far field projection --- p.59 / Chapter 3.3.3.2 --- Near field pattern in k-space --- p.60 / Chapter Chapter 4 --- Analysis --- p.62 / Chapter 4.1 --- Angle-resolved reflectivity measurement --- p.62 / Chapter 4.1.1 --- SPP mode identification --- p.62 / Chapter 4.1.2 --- Wavelength dependence of uncoupled SPPs decay rates --- p.65 / Chapter 4.1.3 --- Directional dependence of uncoupled SPPs decay rates --- p.71 / Chapter 4.2 --- Angle-resolved PL spectroscopy --- p.79 / Chapter 4.2.1 --- Comparison with the angle-resolved reflectivity --- p.79 / Chapter 4.2.2 --- Differentiation of the resonance and off-resonance positions on the PL mapping --- p.81 / Chapter 4.3 --- K-space imaging --- p.83 / Chapter 4.3.1 --- Reflectivity and the comparison with the phase - matching equation --- p.83 / Chapter 4.3.2 --- k-space imaging of the PL emission --- p.85 / Chapter 4.4 --- Directional dependence of the emission factor --- p.86 / Chapter 4.5 --- Directional dependence of the coupling rate of the LDS emission to the SPP mode --- p.94 / Chapter 4.6 --- Near field in k-space from the FDTD method --- p.97 / Chapter Chapter 5 --- Conclusions --- p.113 / Bibliography --- p.115
36

Experimental and theoretical studies of the optical properties of periodic metallic nanostructures. / 週期性金屬鈉米結構光學特性的實驗和理論研究 / CUHK electronic theses & dissertations collection / Experimental and theoretical studies of the optical properties of periodic metallic nanostructures. / Zhou qi xing jin shu na mi jie gou guang xue te xing de shi yan he li lun yan jiu

January 2009 (has links)
By combining experiment and theory, we believe our study shed light on developing a new method for well investigating and controlling the different plasmonic modes and open their way for some great applications in biology, chemistry and photonics. / Finally, this thesis presents an approach to quantitatively evaluate the SP-mediated light emission. Based on this consideration, efforts are taken to find the temperature effect of SP on the light emission in semiconductor. On metal/ZnO system, a more realistic picture for the light emission is depicted by experimentally measuring the temperature-dependent photoluminescence and theoretically calculating the Purcell enhancement factor. The increasing plasmonic density of states with the lower temperature has been regarded as being responsible for the enhanced light emission. / Firstly, studies are performed on finding an in-depth understanding into the optical properties of two-dimensional (2D) metallic nano-cavity structure (grating). Structures are fabricated by interference lithography and thin film techniques. Grating geometries can be easily tuned by using these versatile techniques with high reproducibility and precision. Plasmonic dispersion in the 2D grating has been mapped out by angle-dependent reflectivity measurements. Two particular nanostructures, i.e., nano-bottle array and elliptical hole array, have been chosen to investigate the dependence of plasmonic properties on geometries change. Theories are also put forward to understand the origin and electromagnetic properties of the obtained plasmonic modes. / Surface plasmons (SP), the collective oscillations of the conduction electrons between the metal/dielectric interface, strongly influence the optical properties of metallic nanostructures and are of great interest for future photonic devices. Here, this thesis mainly focuses on the experimental and theoretical investigations on the optical properties of the metallic periodic nanostructures. / With an understanding into the different plasmonic properties of the metallic nanostructures, researches are then undertaken to explore how this associated electromagnetic field interacts with the molecules adsorbed onto a sample surface. The distinct and strong correlation between the plasmonic modes and surface enhanced Raman scattering (SERS) is verified on the one-dimensional silver grating. In particular, the detailed analysis of the enhancement factor from surface plasmons excitation and de-excitation process in SERS has been performed. On the other hand, the technique used to fabricate the controllable "hot spot" for enhancing Raman scattering has been introduced on the 2D metallic grating. Complemented by the theoretical simulation, the conditions for optimizing SERS enhancement effect are proposed. / Li, Jia = 週期性金屬鈉米結構光學特性的實驗和理論研究 / 李佳. / Adviser: Ong Hock Chun. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0388. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 135-144). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / Li, Jia = Zhou qi xing jin shu na mi jie gou guang xue te xing de shi yan he li lun yan jiu / Li Jia.
37

Comparison of SPR and Edge Tracking as a Measure of Binding Kinetics in Whole Cells

January 2018 (has links)
abstract: Most drugs work by binding to receptors on the cell surface. These receptors can then carry the message into the cell and have a wide array of results. However, studying how fast the binding is can be difficult. Current methods involve extracting the receptor and labeling them, but both these steps have issues. Previous works found that binding on the cell surface is accompanied with a small change in cell size, generally an increase. They have also developed an algorithm that can track these small changes without a label using a simple bright field microscope. Here, this relationship is further explored by comparing edge tracking results to a more widely used method, surface plasmon resonance. The kinetic constants found from the two methods are in agreement. No corrections or manipulations were needed to create agreement. The Bland-Altman plots shows that the error between the two methods is about 0.009 s-1. This is about the same error between cells, making it a non-dominant source of error. / Dissertation/Thesis / Masters Thesis Biochemistry 2018
38

Theoretical studies of two-dimensional periodic metallic nano-cavities. / 二維週期性金屬納米共振腔的理論研究 / Theoretical studies of two-dimensional periodic metallic nano-cavities. / Er wei zhou qi xing jin shu na mi gong zhen qiang de li lun yan jiu

January 2009 (has links)
Iu, Hei = 二維週期性金屬納米共振腔的理論研究 / 姚熙. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 89-91). / Abstracts in English and Chinese. / Iu, Hei = Er wei zhou qi xing jin shu na mi gong zhen qiang de li lun yan jiu / Yao Xi. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Introduction to Surface Plasmon Polaritons --- p.3 / Chapter 2.1 --- The Maxwell´ةs Equations --- p.3 / Chapter 2.2 --- Photonic crystals --- p.5 / Chapter 2.3 --- Modeling Metal --- p.9 / Chapter 2.4 --- Surface plasmon polarition --- p.12 / Chapter 3 --- Rectangular Cavity --- p.17 / Chapter 3.1 --- Basic simulation cell setup --- p.17 / Chapter 3.2 --- Method of mode identification --- p.18 / Chapter 3.2.1 --- Dispersion relation calculation --- p.18 / Chapter 3.2.2 --- Reflection spectra --- p.19 / Chapter 3.3 --- Results and discussions --- p.20 / Chapter 4 --- Nano-bottle cavity --- p.25 / Chapter 4.1 --- Cylindrical cavity --- p.25 / Chapter 4.1.1 --- Dispersion relations calculation --- p.25 / Chapter 4.1.2 --- Field pattern calculation --- p.29 / Chapter 4.2 --- Nano-bottle cavity --- p.46 / Chapter 4.2.1 --- The effect of the bottleneck on (0,1) mode --- p.47 / Chapter 4.2.2 --- The effect of aperture size on (0,1) mode --- p.58 / Chapter 4.2.3 --- The effect of the depth of cavities on (0,1) mode --- p.62 / Chapter 4.2.4 --- "The effect of aperture size on (-1,0) mode" --- p.63 / Chapter 4.3 --- Discussions --- p.64 / Chapter 4.4 --- Verified with experimental results --- p.68 / Chapter 5 --- Aspect ratio --- p.71 / Chapter 5.1 --- Simulation structure --- p.72 / Chapter 5.2 --- Aspect ratio S = 2 --- p.73 / Chapter 5.3 --- The effect of aspect ratio --- p.74 / Chapter 5.3.1 --- Orientation dependence of the resonant mode --- p.74 / Chapter 5.3.2 --- Excitation frequency of the resonant mode --- p.75 / Chapter 5.4 --- Field location and strength --- p.76 / Chapter 5.5 --- Discussions --- p.77 / Chapter 5.6 --- Comparison with experimental results --- p.79 / Chapter 6 --- Conclusions and future works --- p.83 / Chapter 6.1 --- A possible new mode excitation --- p.84 / Chapter 6.2 --- Cavities with aspect ratio under p-polarized light --- p.86 / Bibliography --- p.89 / Chapter A --- Computational Simulation --- p.92 / Chapter A.l --- Finite-Difference Time-Domain --- p.92 / Chapter A.2 --- Computational grid --- p.93 / Chapter A.3 --- Boundary Condition --- p.93 / Chapter A.4 --- Source --- p.94 / Chapter A.5 --- Field strength --- p.94
39

Theoretical and experimental investigations on surface plasmon cross coupling mediated emission from ZnO. / 表面等離子交叉耦合協助氧化鋅發射的理論和實驗研究 / Theoretical and experimental investigations on surface plasmon cross coupling mediated emission from ZnO. / Biao mian deng li zi jiao cha ou he xie zhu yang hua xin fa she de li lun he shi yan yan jiu

January 2007 (has links)
Lei, Dangyuan = 表面等離子交叉耦合協助氧化鋅發射的理論和實驗研究 / 雷黨願. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 81-85). / Abstracts in English and Chinese. / Lei, Dangyuan = Biao mian deng li zi jiao cha ou he xie zhu yang hua xin fa she de li lun he shi yan yan jiu / Lei Dangyuan. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations --- p.1 / Chapter 1.2 --- Thesis outline --- p.3 / Chapter 2 --- Background and Proposition --- p.7 / Chapter 2.1 --- Surface plasmon mediated emission from semiconductor --- p.7 / Chapter 2.1.1 --- General mechanism --- p.7 / Chapter 2.1.2 --- Formulation of SP coupling --- p.10 / Chapter 2.1.2.1 --- Derivation of dispersion relation --- p.10 / Chapter 2.1.2.2 --- Plasmonic density of states (DOS) --- p.13 / Chapter 2.1.2.3 --- Field distribution in dielectric/metal/dielectric System --- p.13 / Chapter 2.1.2.4 --- Determination of Purcell factor (Fp) --- p.16 / Chapter 2.1.3 --- Emission enhancement from metal-capped ZnO --- p.17 / Chapter 2.2 --- Proposal for making high efficiency top-emitting LED --- p.22 / Chapter 3 --- Experimental Setup and Measurement System --- p.24 / Chapter 3.1 --- Sample preparation --- p.24 / Chapter 3.1.1 --- Radio frequency magnetron sputtering --- p.24 / Chapter 3.1.2 --- Spin-coating --- p.27 / Chapter 3.1.3 --- Rapid thermal annealing --- p.29 / Chapter 3.2 --- Optical characterizations --- p.29 / Chapter 3.2.1 --- Transmittance measurement --- p.29 / Chapter 3.2.2 --- Photoluminescence (PL) measurement --- p.31 / Chapter 3.2.3 --- EDX for composition measurement --- p.32 / Chapter 4 --- Theoretical Simulations and Experimental Results --- p.36 / Chapter 4.1 --- Tunable surface plasmon resonance by using metal alloys --- p.36 / Chapter 4.1.1 --- Dielectric constants calculation --- p.37 / Chapter 4.1.2 --- Dispersion relation of alloy/Si02 --- p.41 / Chapter 4.1.3 --- Plasmonic density of states and Purcell factor of alloy/semiconductor --- p.43 / Chapter 4.1.3.1 --- Air/AlxAg1-x/ZnO system --- p.43 / Chapter 4.1.3.2 --- Air/AlxAul-x/ZnTe --- p.46 / Chapter 4.1.3.3 --- Air/ AgxAul-x/CdSe system --- p.48 / Chapter 4.1.4 --- Experimental results of AlxAgl-x/ZnO --- p.52 / Chapter 4.1.5 --- Discussion and mini-conclusion --- p.56 / Chapter 4.2 --- Enhanced forward emission from metal-insulator-metal/ZnO by coupled surface plasmon --- p.57 / Chapter 4.2.1 --- Plasmon modes in metal-insulator-metal (MIM) --- p.57 / Chapter 4.2.2 --- Transmittance simulation of MIM and MIMIM --- p.63 / Chapter 4.2.3 --- Transmittance measurement of MIM --- p.68 / Chapter 4.2.4 --- Transmittance and photoluminescence of MIM/ZnO. --- p.73 / Chapter 4.2.5 --- Discussion and mini-conclusion --- p.78 / Chapter 5 --- Conclusions --- p.79 / Chapter 6 --- References --- p.81
40

Broadband nearly perfect absorption in plasmonic absorber based on multiple surface plasmon resonances / 在等離子吸收器中基於多重表面等離子元共振的寬頻近完全吸收 / CUHK electronic theses & dissertations collection / Broadband nearly perfect absorption in plasmonic absorber based on multiple surface plasmon resonances / Zai deng li zi xi shou qi zhong ji yu duo chong biao mian deng li zi yuan gong zhen de kuan pin jin wan quan xi shou

January 2014 (has links)
In complex plasmonic nanostructures, the multiple metal-dielectric interfaces support several elementary modes of surface plasmon polariton. Hybridized surface plasmon polariton (HSPP) is formed due to the evanescent coupling between surface plasmon polaritons on different interfaces. In our first work, we studied the properties of HSPP in a metal-dielectric-metal waveguide with periodically varying refractive index, using Hamiltonian optics approach. We investigated the feasibility of light manipulation inside this structure by extracting the allowed phase orbits using the proposed quantization condition. Besides, the time series of position and wavevector of HSPP are simulated by solving the Hamiltonian equations. The result revealed three distinct HSPP modes formed inside the waveguide: confinement, propagation and retardation. Lastly, we investigated the usage of the proposed structure as an optical filter. / Nearly perfect absorption (NPA) refers to a phenomenon that the reflection and transmission of incident electromagnetic waves on a system are being suppressed, thus the energy of waves is being trapped and dissipated in the system. In our second work, a design of broadband, wide angle of incidence and polarization-independent nearly perfect absorber is proposed based on multiple surface plasmon resonances. The absorptance is computed to confirm NPA for TM and TE modes. Besides, the absorptance depends also on the thickness of the composite layer and this dependence is explained by the hybridized surface plasmon (HSP) formed inside the absorber. Particularly for TE mode, the broadband HSP fast wave which coupled efficiently with the incident light, can only be generated for proper thickness of the composite layer, in contrast to the previous proposal of fast wave generation mechanism using metal/epsilon-near-zero structure to yield narrow-band NPA by S.Feng. The proposed absorber can be used to construct light harvesting devices because of its high efficient energy absorption. / 在複合的等離子納米結構中的多個金屬-電介質介面能支持數個表面等離子激元(surface plasmon polariton)的基礎模態。而雜交化表面等離子激元(hybridized surface plasmon polariton)就是不同表面上的表面等離子激元因衰減性耦合而形成的。在我們第一個工作中,我們以哈密頓光學(Hamiltonian optics)研究了在有週期性折射率變化的金屬-電介質-金屬波導中雜交化表面等離子激元的特性。我們以所提出的量化條件析取出容許的相位軌跡,從而探究在此結構中操縱光波的可行性。此外,雜交化表面等離子激元的位置和波向量隨時間的變化會通過解哈密頓方程計算出來。結果顯示在此波導中,雜交化表面等離子激元有三種不同的模態:密閉,傳播,延滯。最後,我們探討了此結構作為光學過濾器的應用。 / 近完全吸收(Nearly perfect absorption)是指射在一系統上的電磁波的反射和傳輸都被壓制,而波的能量則被困鎖和消耗在系統中的一個現象。在我們第二個工作中,我們提出了一個基於多重表面等離子元共振的寬頻、廣入射角、與偏振無關的近完全吸收器設計。我們計算了吸引率以確認在TE及TM模態下的近完全吸收。此外,吸引率亦與複合層的厚度有關,而此關係能以在吸收器形成的雜交化表面等離子解釋。特別是TE模態時,能有效地與入射光耦合的寬頻雜交化表面等離子快波(Broadband HSP fastwave)只能在合適的厚度才能產生,與S.Feng所提出以金屬/近零介電常數材料結構產生快波,從而達至窄頻近完全吸收不同。因為高效能的能量吸引,我們提出的吸收器能作建構光收集裝置之用。 / Lee, Sze Fung = 在等離子吸收器中基於多重表面等離子元共振的寬頻近完全吸收 / 李時鋒. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 58-62). / Abstracts also in Chinese. / Title from PDF title page (viewed on 24, October, 2016). / Lee, Sze Fung = Zai deng li zi xi shou qi zhong ji yu duo chong biao mian deng li zi yuan gong zhen de kuan pin jin wan quan xi shou / Li Shifeng. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

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