Dissertations / Theses on the topic 'Nanoring'

In this thesis, the growth of metal-free naphthalocyanine (Nc) and copper naphthalocyanine (CuNc) on both bare Si/SiO2 and octadecyltrichlorosilane (OTS) modified Si/SiO2 surface were studied. The effects of the substrate temperature on morphology and structure of Nc and CuNc thin film growth were presented. For these purposes thin films of Nc and CuNc prepared by thermal vacuum evaporation were studied using atomic force microscopy (AFM) and X-ray diffraction (XRD). We observed that the increase of substrate temperature during growth affects the morphology, preferential molecular orientation and degree of crystallinity of both Nc and CuNc thin film, which were used as active layers in organic field effect transistor (OFET) devices. Organic thin film transistors (OFETs) were fabricated using these molecules as the active layers and their electrical characteristics were measured under both vacuum and atmospheric conditions and they were found to exhibit p-type transistor action. A series of samples of the Nc and CuNc thin films were grown on Si/SiO2 and OTS-modified oxide surface at different substrate temperature but fixed equivalent deposited thickness. The growth conditions, particularly the substrate temperature strongly affect nucleation size and shape of the organic thin film. In general, the thin film morphology shows a near circular grain and elongated grain shape at low substrate temperature, while the thin Nc film shows small needle-like structure and extended needle-like crystalline structures with large gaps at high substrate temperature. The optimum substrate temperature during the growth of Nc on both surfaces is achieved at 200 °C, and this occurs for growth of CuNc at 180 °C and 160 °C on Si/SiO2 and OTS surfaces, respectively, for which the naphthalocyanine thin film shows the best morphological and electrical properties. We used Nc and CuNc thin films prepared at different substrate temperatures as active layers to fabricate bottom and top-contact organic field effect transistors. Their electrical characteristics were measured at room temperature in vacuum and air in the dark. We plotted the output characteristic and transfer characteristic of all OFET devices so that the effects of grain size and crystal structure on the performance characteristic of Nc OFET device could be investigated. Then we studied the effects of hysteresis and charge traps on device performance when exposed to air. We found that the changes generated by exposure of the device to atmosphere may be reversed by annealing the thin film to ∼100 °C in vacuum. We reported the highest mobility of (5.16 ± 0.23) × 10-2 cm2 /Vs for top-contact Nc device prepared at 200ºC on SiO2 after annealing in vacuum, and also we reported the highest mobility of (3.56 ± 0.14) × 10-2 cm2 /Vs for top-contact CuNc device prepared at 180ºC on SiO2 after annealing in vacuum. We found that the top-contact device always performs better than the bottom-contact device. We attributed this to the change of morphology of active layer in the interface between contact metal and SiO2. Solvent induced self-assembly, self-trapping, and self-organizing of c-P30 cyclic porphyrin polymers on the Au surface that are deposited from two solutions and various concentrations in ambient condition was also studied. This results in the arrangement of cyclic polymers in different configurations such as stacking columnar, supramolecular nesting and uniform height hexagonal close packed structure. These conformations are observed using scanning tunnelling microscopy. Highly covered surface stacking columnar like porous array is also observed. We show that toluene:methanol mixture can play a crucial role in self-assembly of supramolecular structure in two dimensions, π-π stacking conformation perpendicular over surface in three dimensions and single in double nested nanoring conformation. Cyclic porphyrin polymers deposited from toluene shows nested nanorings structure, such as single nanoring self-trapped inside a near-circular shape single ring on surface. Diluted solutions using a large volume of methanol relative to the toluene can suppress the adsorption of nanorings to the surface. Interestingly, adsorption of the cyclic polymer from toluene:methanol 3:5 can result in the formation of uniformly height hexagonal close packing on surface, where nanorings aggregate as columnar stacks in two layers, dependent on concentration. Our results show that the self-assembly of artificial cyclic polymers is dependent on solvent and concentration provides a significant step towards control of the three-dimensional arrangement of supramolecular conformation on surfaces using non-covalent interactions.

Frequently, the dental surgery one faces serious problems of defects osseous and loss of teeth; this means that those must be replaced by prostheses or implants to reconstitute the function and static. These materials were called biomaterials, since they interact with the systems made up of cells and fabrics. It is currently difficult to give a definition of "biomaterial" since the concepts changed in the last few years. We can however define a biomaterial as "a nonbiological material which interacts with biological systems" (Williams 1987). Since it interacts with biological systems, this material must be biologically accepted or at least no cause tissue injure; consequently we must also give a definition of "biocompatibility" which is "the capacity of a material to induce a suitable answer of the host for a specific application" (Williams 1987). These terms are appropriate in the majority of materials currently used like biomaterials, however the "nonbiological" term is not completely exact, since many materials used like biomaterials or medical devices are of biological origin, such is the case of bone grafts. One already used a large variety of materials like biomaterials, metals, ceramics, polymers, glasses, carbon, and composite materials. There are many examples of applications of the biomaterials: cardiac valves, articulations of knee, implants dental, intraocular lenses, etc. Now, many medical fields use the biomaterials. Each year in the United States more than 30. 000 prostheses of the knee and hip also 100. 000 to 300. 000 dental implants are placed (D. A. Puleo, 1999). In the European Community more than 50. 000 prostheses of hip and approximately 100. 000 dental implants are placed (SIMI Project). These statistics increase each year as the materials used get a greater safety with their patients, which also tend to lower the costs, by facilitating their good use gradually. One of most significant advanced in this field, was "the material bioactive" design. I. E. Works with the design and the development of biomaterials to which biologically activated molecules were built-in, in order to control the cellular answer. One conceived a series of process to this end by stressing polymer adhesion at surface of materials. The method suggested by Decher is of a great interest for self-assembly polyelectrolytes thin films made on the surface of materials. The alternate absorption of polyelectrolytes anion and cation on solid surfaces gives us the possibility of forming the multi-layer ones of very thin polyelectrolytes, which constitutes a versatile technique to modify surfaces. This possibility is of a great attraction for industry and medicine. The most significant characteristic of the polyelectrolytes is their capacities to be charged electrically in solution, which gives us the possibility of forming self-assembly polyelectrolytes films, with the possibility of intercalating and of immobilizing a large variety of made up on treated surface, such with inorganic particles or organics like proteins, the enzymes, etc, by providing to the surface of material really active characteristics, which constitute new strategies to control the answer of the host. This can be the key for the design and manufacture of biomaterials bioactives able to control the answer of the host at the molecular level by creating an adequate, fast and directed answer. Our work consisted in : the study of the formation of nanoring, the study of the adsorption of proteines on films in a field of precise pH, the study of the adhesion of cells on films of polyelectrolytes for micro aspiration. We studied the adsorption of the HSA on films made of polypeptides, the poly(L-lysine) (PLL), and the acid poly(glutamique) (PGA) in a field of pH 3. 0-10. 5. We showed that adsorption depends enormously on the last layer of the film. For the PLL, to low pH, an electrostatic repulsion limits adsorption. With the pH superiors one on adsorption of HSA on the PGA is observed. This is with the conformation of the rich PGA helical alpha which increases the roughness of film. Finally, we studied the adhesion of cells of films of polyelectrolytes. All the biological processes are achieved thanks to weak specific molecular interactions which generate connections of short duration; too strong interactions would remove all dynamics essential to the life. We thus evaluated by the technique of micromanipulation by micropipette the short-term interactions of cells with multi-layer films. By grafting hundreds of cells on a substrate, one will be able to distinguish the mechanical answers from the healthy cells. The goal of this work was the modulation of the multi-layer film properties with respect to the cellular adhesion. We observed also at the time of the deposit of PSS on a layer of PEI, the formation of circular structures. We named these structures of the nanorings. These structures are variable sizes of 300 Nm diameters to 2 µm diameter between the various experiments but by experiment, are of very homogeneous size. Such structures had never been observed. We thus sought to include/understand the mechanisms of controls and formation of these structures. These observations were realizes in AFM by using a liquid cell which prevents the appearance of artefacts due to dehydration. We determined that the two parameters which control the size of the nanoring are the size of the pores of the filters used for the preparation of the solution of PSS and the time of contact of the solutions with the air. Indeed, divalent ions CO3 -- play a dominating role in the formation of this nanoring. It is about a mechanism of car-assembly of hydrophobic complexes of PSS on the surface of film of PEI. The size being controlled by a balance enters the electrostatic repulsions and hydrophobic attractions and under the dependence of the electrostatic interactions between the PEI and the PSS
Fréquemment, la chirurgie dentaire fait face à de graves problèmes de défauts osseux et compris la perte de dents; ceci signifie que celles-ci doivent être remplacées par des prothèses ou implants pour reconstituer la fonction et l'esthétique. Ces matériaux ont été appelés des biomatériaux, puisqu'ils interagissent avec les systèmes constitués de cellules et de tissus. Il est actuellement difficile de donner une définition de " biomatériau " puisque les concepts ont changé durant ces dernières années. Nous pouvons toutefois définir un biomatériau comme " un matériau non biologique qui interagit avec des systèmes biologiques " (Williams 1987). Puisqu'il interagit avec des systèmes biologiques, ce matériau doit biologiquement être accepté ou au moins ne pas provoquer de dommages tissulaires ; par conséquent nous devons aussi définir le terme " biocompatibilité " qui est " la capacité d'un matériau à induire une réponse appropriée de l'hôte pour une application spécifique " (Williams 1987). Ces termes conviennent à la majorité des matériaux actuellement utilisés comme biomatériaux, toutefois le terme " non biologique " n'est pas tout à fait exact, puisque beaucoup des matériaux utilisés comme biomatériaux ou dispositifs médicaux sont d'origine biologique, tel est le cas des greffes de tissus. On a déjà utilisé une grande variété de matériaux comme biomatériaux, métaux, céramique, polymères, verres, carbone, et matériaux composites. Il existe de nombreux exemples d'applications des biomatériaux : les valves cardiaques, les articulations de genou, les implants dentaires, les lentilles intraoculaires, etc. Actuellement, de très nombreux domaines médicaux utilisent les biomatériaux. Chaque année aux Etats-Unis plus de 30. 000 prothèses du genou et de hanche aussi que 100. 000 à 300. 000 implants dentaires sont placés (D. A. Puleo, 1999). Dans la Communauté Européenne sont placés plus de 50. 000 prothèses de hanche et environ 100. 000 implants dentaires (SIMI Project). Ces chiffres augmentent chaque année au fur et à mesure que les matériaux utilisés procurent une plus grande sécurité à leurs patients, ce qui tend aussi à abaisser les coûts, en facilitant progressivement leur bon usage. Une des avancées les plus importantes dans ce domaine, a été la conception de " matériaux bioactifs ". C'est-à-dire que l'on travaille à la conception et l'élaboration de biomatériaux auxquels des molécules biologiquement activées ont été incorporées, afin de contrôler la réponse cellulaire. On a conçu une série de processus dans ce but en mettant l'accent sur l'adhésion de polymères à la surface des matériaux. La méthode proposée par Decher est d'un grand intérêt pour l'autoassemblage de film de polyélectrolytes à la surface des matériaux. L'absorption alternée de polyélectrolytes anioniques et cationiques sur des surfaces solides nous donne la possibilité de former des multicouches de polyélectrolytes très minces, ce qui constitue une technique ubiquitaire pour modifier des surfaces. Cette possibilité est d'un grand attrait pour l'industrie et la médecine. La caractéristique la plus importante des polyélectrolytes est leur capacités d'être chargé électriquement en solution, ce qui nous donne la possibilité de former des films alternés de polyélectrolytes autoassemblés, avec la possibilité d'intercaler et d'immobiliser une grande variété de composés sur la surface traitée, telles de particules inorganiques ou organique comme des proteines, les enzymes, etc. , en fournissant à la surface du matériau des caractéristiques réellement actives, qui constituent de nouvelles stratégies pour contrôler la réponse de l'hôte. Celle-ci peut être la clé pour la conception et fabrication de biomatériaux bioactifs capables de contrôler la réponse de l'hôte au niveau moléculaire en créant une réponse adéquate, rapide et dirigée. Notre travail a consisté en : l'étude de la formation de nanoring, l'étude de l'adsorption de proteines sur des films dans un domaine de pH précis, l'étude de l'adhésion de cellules sur des films de polyelectrolytes pour micro aspiration. Nous avons observé lors du dépôt de PSS sur une couche de PEI, la formation de structures circulaires. Nous avons nommé ces structures des nanorings. Ces structures sont de tailles variables de 300 nm de diamètre à 2 µm de diamètre entre les différentes expériences mais par expérience, sont de taille très homogène. De telles structures n'avaient jamais été observées. Nous avons donc cherché à comprendre les mécanismes de contrôles et de formation de ces structures. Ces observations ont été réalise en AFM en utilisant une cellule liquide qui prévient l'apparition d'artéfacts dus à la déshydratation. Nous avons déterminé que les deux paramètres qui contrôlent la taille des nanoring sont la taille des pores des filtres utilisés pour la préparation de la solution de PSS et le temps de contact des solutions avec l'air. En effet, les ions divalents CO3—jouent un role prépondérant dans la formation de ces nanoring. Il s'agit d'un mécanisme d'auto-assemblage de complexes hydrophobiques de PSS à la surface du film de PEI. La taille étant contrôlée par une balance entre les répulsions électrostatiques et les attractions hydrophobiques et sous la dépendance des interactions électrostatiques entre le PEI et le PSS. Nous avons étudié aussi l'adsorption de la HSA sur des films formé de polypeptides, la poly(L-lysine) (PLL), et l'acide poly(glutamique) (PGA) dans un domaine de pH 3. 0-10. 5. Nous avons démontré que l'adsorption dépend énormément de la couche supérieure des films. Pour le PLL, à pH bas, une répulsion électrostatique limite l'adsorption. Aux pH supérieurs une sur adsorption de HSA sur le PGA est observé. Ceci est du à la conformation du PGA riche en hélice alpha qui augmentent la rugosité du film. Finalement, nous avons étudié l'adhésion de cellules des films de polyelectrolytes. Tous les processus biologiques s'accomplissent grâce à des interactions moléculaires spécifiques faibles qui génèrent des liaisons de courte durée; des interactions trop fortes supprimeraient toute la dynamique indispensable à la vie. Nous avons donc évalué par la technique de micromanipulation par micropipette les interactions à court terme de cellules avec des films multicouches. En greffant des centaines de cellules sur un substrat, on pourra distinguer les réponses mécaniques des cellules saines. Le but de cette travail a été la modulation des propriétés de films multicouches vis à vis de l'adhésion cellulaire

In the pursuit of economical and rapid fabrication solutions on the micro and nano scale, polymer replication has proven itself to be a formidable technique, which despite zealous development by the research community, remains full of promise. This thesis explores the potential of elastomers in what is a distinctly multidisciplinary field. The focus is on developing innovative fabrication solutions for planar photonic devices and for nanoscale devices in general. Innovations are derived from treatments of master structures, imprintable substrates and device applications. Major contributions made by this work include fully replicated planar integrated optical devices, nanoscale applications for photolithographic standing wave corrugations (SWC), and a biologically templated, optical fiber based, surface-enhanced Raman scattering (SERS) sensor. The planar devices take the form of dielectric rib waveguides which for the first time, have been integrated with long-period gratings by replication. The heretofore unemployed SWC is used to demonstrate two innovations. The first is a novel demonstration of elastomeric sidewall photolithographic mask, which exploits the capacity of elastomers to cast undercut structures. The second demonstrates that the corrugations themselves in the absence of elastomers, can be employed as shadow masks in a directional flux to produce vertical stacks of straight lines and circles of nanowires and nanoribbons. The thesis then closes by conceptually combining the preceding demonstrations of waveguides and nanostructures. An optical fiber endface is em ployed for the first time as a substrate for patterning by replication, wherein the pattern is a nanostructure derived from a biological template. This replicated nanostructure is used to impart a SERS capability to the optical fiber, demonstrating an ultra-sensitive, integrated photonic device realized at great economy of both time and money, with very real potential for mass fabrication.

Les oligophénylènes constituent une classe de molécules centrale dans la conception de semi-conducteurs organiques pour des applications optoélectroniques. Ces travaux portent sur la synthèse et l’étude approfondie de dérivés linéaires et cycliques du fluorène (un biphényle rigidifié par un pont méthylène), fragment constitutif essentiel dans l’électronique organique. Nous nous intéressons en particulier aux relations structure-propriétés de ces systèmes π-conjugués. Dans une première partie, avec comme cadre le développement de matériaux hôtes pour diodes électroluminescentes (PhOLEDs), nous présentons une étude de la régioisomérie de phényl-fluorènes et de phényl-spirobifluorènes. Ses résultats ont permis la préparation de quatre matériaux hôtes purs hydrocarbures, dimères de spirobifluorène, intégrés dans des PhOLEDs bleues à hautes performances. Dans une seconde partie, nous nous intéressons au domaine récent des nano-anneaux moléculaires, objets cycliques présentant une conjugaison π de nature singulière. Après une revue bibliographique portant sur les cycloparaphénylènes et leurs propriétés, nous présentons nos études concernant plusieurs exemples de leurs analogues pontés : les cycloparafluorènes
Oligophenylenes constitute a major class of molecules in the design of organic semiconductors for optoelectronics applications. This work involves the synthesis and in-depth study of linear and cyclic derivatives of fluorene (a biphenyl rigidified by a methylene bridge), an essential building block in organic electronics. We focus our attention on the structure-property relationships of these π-conjugated systems. In a first part, within the framework of host materials for phosphorescent organic light-emitting diodes (PhOLEDs), we present a regioisomerism study of phenyl-fluorenes and phenyl-spirobifluorenes. Its results enabled the preparation of four pure hydrocarbon host materials, spirobifluorene dimers, used in high-performance blue PhOLEDs. In a second part, we take interest in the emerging field of molecular nanorings, cyclic objects presenting a singular nature of π-conjugation. After a bibliographical review covering cycloparaphenylenes and their properties, we present our studies regarding several examples of their bridged analogues: cycloparafluorenes

This thesis presents a combined experimental and computational evaluation of the physical-organic properties of butadiyne-linked porphyrin oligomers. The principal result from the thesis is the synthesis and characterisation of the largest aromatic and antiaromatic systems to date, in the form of an oxidised [6]-porphyrin nanoring, with diameter 2.4 nm. This large electronically coherent system provides insight into the connection between aromatic ring currents and persistent currents in metal and semiconductor mesoscopic rings. Chapter 1 briefly reviews the concepts used in the remainder of the thesis, with a particular focus on aromaticity. In Chapter 2, the barrier to inter-porphyrin torsional rotation in a butadiyne-linked porphyrin dimer is determined computationally and experimentally to be 3 kJ mol^-1. The barrier height is closely related to the resonance delocalisation energy between the porphyrin subunits. In Chapter 3 we show that by oxidising a butadiyne-linked [6]-porphyrin nanoring to its 4+ and 6+ oxidation states, the nanoring becomes antiaromatic and aromatic respectively. In contrast, the neutral oxidation state exhibits only local aromaticity for the six porphyrin units. The 12+ cation can also be generated, and exhibits local antiaromaticity for each porphyrin unit. The characterisation of (anti)aromaticity employs NMR and computational techniques. In Chapter 4, the properties of cation radicals of linear and cyclic porphyrin oligomers are explored. Cations generated by spectroelectrochemistry are measured by optical spectroscopies, and chemically generated radical monocations are examined by cw/pulsed EPR spectroscopies. EPR and optical spectroscopies agree that the dimer monocation radical is fully delocalised, in Robin-Day Class III, whereas the monocations of longer oligomers are localised over 2-3 porphyrin units (Class II). In Chapter 5, photophysical and computational investigations into excited state aromaticity in porphyrin nanorings are presented. The computational results suggest the presence of aromaticity in the triplet excited states, but experiment fails to convincingly demonstrate the effect. Computational results in Chapter 6 show that a butadiyne linked [6]-porphyrin nanoring in which one butadiyne (C≡C-C≡C) is truncated to an alkyne (C≡C) exhibits a reversal of aromaticity and antiaromaticity in its oxidised states, compared to the all-butadiyne linked nanoring, consistent with Hückel's law.

This report gives a short introduction of the Norwegian wireless electronics company Chipcon AS, and goes on to account for the state of the art of small IP processor cores. It then describes the NanoRisc, a powerful processor developed in this project to replace hardware logic modules in future Chipcon designs. The architecture and a VHDL implementation of the NanoRisc is described and discussed, as well as an assembler and instruction set simulator developed for the NanoRisc. The results of this development work are promising; synthesis shows that the NanoRisc is capable of powerful 16-bit data moving and processing at 50 MHz in an 18nm process while requiring less than 4500 gates. The report concludes that the NanoRisc, and none of the existing IP cores studied, satisfies the requirements for hardware logic replacement in Chipcon transceivers.

New templates based on the structures of cyclodextrin and ferrocene have been developed for porphyrin nanoring syntheses. Flexibility can be taken into account of the molecular template design. The flexibility of butadiyne bonds allow the formation of a 5-porphyrin nanoring, which is the smallest fully-conjugated porphyrin nanoring to date. Chapter 1 describes the general information of porphyrin, cyclodextrin and ferrocene, which are used as basic structures in the thesis. The polymer chemistry of porphyrins is reviewed as the background knowledge of the work. Meanwhile, chelate cooperativity of supramolecular systems and the corresponding measurement method are introduced. Chapter 2 presents the chemistry towards 6- and 7-porphyrin nanorings using molecular templates T6* and T7*, which are based on the a- and β-cyclodextrin scaffolds. The cooperativity of respective template-nanoring complexes was investigated by UV-vis titrations. Chapter 3 describes the Vernier-templated syntheses of porphyrin nanorings using T7* and different linear porphyrin oligomers (l-P2, l-P4 and l-P8). Both chapters focus on the influences of spatial preorganization and flexibility to the cooperativity of supramolecular systems. Chapter 4 introduces the chemistry towards a ferrocene-based five-dentate template T5 which successfully directed the syntheses of 5-porphyrin nanorings. Investigation of the cooperativity in the nanoring-template system is presented. Chapter 5 investigates the cooperativity between T5 and linear porphyrin oligomers in detail; and focuses on the contribution of partially-bound complexes in the measurement of equilibrium constants of the host-guest systems. Both chapters focus on the influences of intramolecular strain to the cooperativity in supramolecular systems. Chapter 6 provides experimental procedures and characterization data of the known and novel compounds synthesized in the course of completing the thesis.

This thesis is concerned with the photophysical properties of porphyrin nanorings. In particular, the impact of symmetry, conformation and structure on electronic delocalization, radiative rate and emission polarization memory loss are investigated and exciton migration is probed on a number of porphyrin nanorings. Ultrafast time-resolved spectroscopy techniques are used to study the fluorescence dynamics of these newly synthesized compounds. First, photophysical implications of lifting the rotational symmetry are investigated using a number of small porphyrin rings specially modified for this purpose. For more severe symmetry distortions, increased optical transitions to the lowest excited state have been observed, which is dipole-forbidden due to symmetry reason. Also, the degeneracy in the allowed first excited state is lifted for broken symmetry, leading to a polarization switching effect. The effect of conformation on emission depolarization memory loss is studied using a series of similarly sized porphyrin rings with rigid structures exhibiting various degrees of out-of-plane distortion. Excitations can access any segment on the nanoring and this is not affected by the conformation. However, severe out-of-plane distortions lead to lowered emission anisotropy; this conclusion is further supported by molecular dynamics simulation. Finally, exciton migration within porphyrin ring complex is investigated. Russian doll complex which consists of two concentric porphyrin rings acts as a single emitter, even though spectral features of both ring components are found in the absorption spectrum. Lifetimes and radiative rates of the complex and the individual rings components further confirmed that excitons migrate from the outer 12-ring to the inner 6-ring within 40 ps. A nanotube consisting of two conjugated 6 porphyrin rings linked by dimers acting as staves also exhibits energy migration. Emission anisotropy measurements suggest that excitation is transferred from the staves of the nanotube to the ring plane effectively within 280 fs.

This thesis describes supramolecular approaches to porphyrin nanorings. Cyclic porphyrin arrays resemble natural light harvesting systems, and it is of interest to probe the photophysical effects of bending the porphyrin aromatic π-system. A general overview of the synthesis and photophysical properties of porphyrins and their arrays is carried out in Chapter 1. The electronic structure of porphyrins is examined, and how conformational effects in oligomers, such as inter-porphyrin torsional angle and backbone bending influence the π-conjugation pathway. The structures of light harvesting complexes are discussed. Chapter 2 describes the design and synthesis of a complementary 12-armed template designed to coordinate linear porphyrin oligomers in the correct conformation for cyclisation to give a cyclic porphyrin dodecamer. Chapter 3 demonstrates two approaches to a cyclic porphyrin dodecamer ring. Firstly, a classical templating approach using the 12-armed template is described. The limitations of this approach in the quest for larger nanorings are discussed. Vernier templating, which utilises a mismatch in the number of binding sites between a ligand and its receptor is introduced as a general strategy to the synthesis of large nanorings. This is demonstrated by the synthesis of cyclic dodecamer from a linear porphyrin tetramer and a hexadentate template via a figure-of-eight intermediate. The general utility of the Vernier method to large nanorings is explored in Chapter 4 with steps towards the synthesis of a cyclic tetracosamer, consisting of 24 porphyrin subunits. In preliminary experiments, an improved route to the cyclic porphyrin octamer is described. Finally, the photophysical properties of the nanoring series are explored in Chapter 5 as a function of size and conformation. Femtosecond photoluminescence spectroscopy shows that even in cyclic dodecamer, exciton delocalisation over the entire porphyrin backbone occurs on a sub-picosecond timescale, and parallels are drawn with the dynamics of natural light harvesting complexes.

Fully conjugated porphyrin nanorings combine an end-free π-system with well defined size and shape. They provide models for testing our understanding of light harvesting in natural photosynthetic systems, and may lead to the creation of new functional materials. This thesis describes the template-directed synthesis of novel 10, 16, 18, 20, 24, 30, 40 and 50-porphyrin nanorings using small templates, as well as the investigation of their structure, electronic properties and supramolecular chemistry in solution and on surfaces. This work illustrates the scope of Vernier templating as a tool for the synthesis of monodisperse molecules of unprecedented sizes. Chapter 1 introduces key properties of porphyrins and π-conjugated linear and cyclic porphyrin oligomers and describes the principle methods of preparing non-conjugated and conjugated cyclic polymers. It also covers recent advances in the synthesis of fully-conjugated porphyrin nanorings, in particular Vernier templating. Chapter 2 discusses the formation of higher order porphyrin nanorings (18- and 24-porphyrin nanorings) in the classical synthesis of 6-porphyrin nanoring and the Vernier-templated synthesis of 12-porphyrin nanoring. Chapter 3 describes the Vernier-templated synthesis of 24-porphyrin nanoring and its characterization. Chapter 4 shows that the flexibility of 24-porphyrin nanoring can be locked by the formation of a “sandwich” complex in the presence of a bidentate ligand or by solvent-induced formation of aggregates. Chapter 5 demonstrates the use of templates to control the cyclooligomerization of linear porphyrin oligomers. Vernier-templated synthetic routes to 10-, 30- and 40-porphyrin nanorings are investigated. Chapter 6 reports the electronic properties of porphyrin nanorings as probed by electrochemistry (for 6 porphyrin nanoring) or fluorescence anisotropy measurements (for 24 porphyrin nanoring). Crystal structures of 6 and 12 porphyrin nanoring template complexes are presented. Chapter 7 contains experimental procedures and characterization data of known and novel compounds synthesized in the course of this thesis.

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 32-33).
Magnetic nanorings (MNRs) are anisotropic nanomaterials that can support a magnetic vortex state, which can yield both colloidal stability and large hysteretic power losses when exposed to an alternating magnetic field (AMF). Coupled with the biocompatibility of polymer surface coatings, MNRs have the potential of being used for many biological applications, including neuronal stimulation, drug delivery, and cancer hyperthermia. In this work, we synthesized varying geometries of MNRs via a thermal decomposition route and characterize their structural, chemical, and magnetothermal properties. Scanning and transmission electron microscopy was used to analyze surface morphology and geometry of nanostructures. X-ray diffraction allowed for differentiation of paramagnetic and ferrimagentic phases of synthesized iron oxide. Vibrating scanning magnetometry and induced coupled plasma atomic emission spectroscopy were used to determine magnetic properties, including saturation magnetization (Ms) and coercive field (He). Finally, calorimetric measurements were performed to calculate specific power losses (SLPs) of varying compositions of MNRs. We demonstrate that MNRs exhibit hysteretic power loss and can be optimized for neuronal stimulation under biologically safe AMF conditions.
by Francisco J. Garcia.
S.B.

Multilayered metallo-dielectric nanoparticles are increasingly considered in various applications to control the spatial and temporal behavior of electromagnetic fields. In particular, the surface mode excitation by photons or electrons in metal nanorings finds significant applications because of the implied field distribution and electromagnetic energy confinement. However, most solid nanorings that are multilayered and/or embedded in a medium have non-simply connected geometry resulting in surface modes which are not linearly independent. That is, unlike particle plasmon eigenmodes in other geometries, the amplitudes of the eigenmodes of tori exhibit a distinct forward and backward coupling. We investigate the surface modes of such toroidal nano-structures and obtain the canonical plasmon dispersion relations and resonance modes for arbitrarily layered nanorings. When seeking the nonretarded surface modes for a stratified solid torus, we obtain a three-term difference equation which plays an important role in obtaining the needed dispersion relations. The obtained dispersion relations are investigated in depth in terms of the involved matrix continued fractions and their convergence properties including their determinant forms for computing the plasmon eigenmodes. The numerical solutions of the dispersion relations in case of a solid ring are presented for comparison and the resonance frequencies for the first few dominant modes of a ring composed of plasmon supporting materials such as gold, silver, and aluminum are provided and compared to those for a silicon ring. The mode complementarity and hybridization in multilayered toroidal structures is discussed and different ring configurations are simulated in the quasistatic limit by selecting number of layers modeled by their local dielectric functions. A generalized Green’s function with derivation intricacies addressed for multilayer tori is obtained from which one may calculate and study the scattering behavior of any of the modes that may exist in the many layer system. In particular, the electric potential distribution corresponding to individual poloidal and toroidal modes in response to an arbitrarily polarized external field and the field of electrons is obtained. The results are applied to obtain the local density of states and decay rate of a dipole near the center of the torus. Finally, two new types of toroidal particles in the form of janus nanorings are introduced.

In the paper, dipole-exchange spin excitations in a composite nanorice-type nanoparticle (prolate rotation ellipsoid) are investigated theoretically. A nanorice with a non-magnetic core and a shell composed of an uniaxial ferromagnet is considered. Spin dynamics in the above-described nanosystem is described using the linearized Landau-Lifshitz equation (in the magnetostatic approximation) with the addends that consider the magnetic dipole-dipole interaction, the exchange interaction and the anisotropy effects. An equation for the magnetic potential of the above-described spin excitations is obtained. For the case of a thin shell, a solution for the above-mentioned equation in the form of a combination of the generalized spheroidal functions is proposed. For the above-described case, a dispersion relation for such spin excitations is also found.

Exoribonucleases are indispensable for cellular RNA metabolism. RNA processing, end-turnover, and degradation all require the concerted action of exoribonucleases. In this thesis, two families of exoribonucleases that act in the final steps of RNA decay pathways are explored. The first of these is the RNR superfamily of processive 3’→5’ RNases with major roles in both mRNA and stable RNA degradation. The initial focus of this work is the structural and enzymatic characterization of an unusual RNR family enzyme from the radiation-resistant bacterium Deinococcus radiodurans. This enzyme is demonstrated biochemically to be an RNase II-type enzyme (DrII), based on its sensitivity to secondary structure. Analysis of the DrII X-ray structure reveals that a novel, winged-HTH domain has replaced the canonical RNA binding clamp typical of RNR family proteins. The exposed architecture of DrII’s RNA binding surface offers an explanation for the nuclease’s ability to approach within 3-5 nt of a duplex, an important mechanistic difference from the well-studied E. coli RNase II. The open, clamp architecture of DrII may have broader relevance to mechanisms of duplex RNA recognition in the RNR superfamily. RNA decay by processive exonucleases such as RNR family proteins leaves 2-5 nt nanoRNA limit products that are further degraded to mononucleotides by nanoRNases. In E. coli, the DEDD family enzyme Oligoribonuclease (ORN) executes nanoRNA decay and represents the first major family of nanoRNases, with homologs widely conserved in eubacteria and eukaryotes. The B. subtilis NanoRNase A (NrnA), a DHH family phosphoesterase, represents a second major class of nanoRNases, with broad phylogenetic distribution in organisms that lack orn homologs. The second major focus of this thesis is a structural and mechanistic study of this nanoRNase machinery. The atomic structure of the B. subtillis nanoRNase NrnA is described, and unveils a bi-lobal architecture similar to the 5’→3’ DNase RecJ, where the catalytic DHH domain is linked via a partially helical connector to the C-terminal RNA binding domain. NrnA is a highly dynamic molecule, adopting both open and closed conformations. Co-crystallization with several substrates shows that NrnA has a nanoRNA specific substrate-binding patch that offers a structural explanation for its 3’→5’ nanoRNase activity. This RNA binding site feeds substrate to the DHH active site in an orientation opposite to the 5’→3’ path proposed for RecJ. Surprisingly, NrnA also maintains a weak 5’→3’ activity on certain substrates, and thus possesses both 5’→3’ and 3’→5’ exonuclease activities. In conclusion, an overall model is presented for how DHH family exonucleaess can degrade nucleic acids from both the 5’→3’ and 3’→5’ directions. Thus, the studies described in this thesis offer both an atomic and a biochemical view of the macromolecular machinery critical to the degradation of RNA.

L’électronique organique est un domaine de recherche qui vise à développer de nouvelles technologies basées sur des matériaux semi-conducteurs organiques (SCOs). D’une manière générale, deux approches sont utilisées pour le design moléculaire de SCOs. La première approche consiste à assembler des fragments moléculaires, connus pour certaines propriétés, afin de synthétiser des matériaux fonctionnels pour une application visée comme les diodes électrophosphorescentes organiques (PhOLEDs). La seconde approche est plus exploratrice et consiste à développer des nouveaux fragments moléculaires pouvant posséder une ou plusieurs propriétés souhaitées pour une application donnée. Dans ces travaux de thèse les deux approches ont été développées. D’un côté, nous avons élaboré des matériaux hôtes pour des PhOLEDs en ajustant leur propriétés (première approche), et, de l’autre côté, nous nous sommes intéressés à une toute nouvelle génération de SCOs : les anneaux moléculaires (seconde approche). Dans une première partie, avec comme cadre le développement de nouvelles matrices hôtes pour des PhOLEDs simplifiés dites monocouches, nous présenterons une étude de deux familles de SCOs basé sur un design moléculaire Donneur-spiro-Accepteur. Ses travaux ont permis la fabrication de PhOLEDs rouge, verte et bleue présentant les performances globales les plus élevées de la littérature. Dans une seconde partie, après un chapitre bibliographique détaillé sur la synthèse et les propriétés singulières des anneaux moléculaires, nous présenterons une étude approfondie des propriétés de deux familles d’anneaux moléculaires constitués d’unités carbazoles. Ces travaux nous ont permis d’incorporer pour la première fois des anneaux moléculaires dans des transistors organiques à effet de champs afin d’en étudier les propriétés de transport
Organic electronics is a field of research dealing with the development of new technologies based on organic semiconductor materials (OSCs). In general, two approaches are used for the molecular design of OSCs. The first approach consists in assembling efficient molecular fragments, in order to synthesize functional materials for a specific application such as phosphorescent organic light-emitting diodes (PhOLEDs). The second approach is more risky as it aims to develop new molecular fragments which may have one or several desired properties for a given application. In this thesis work, both approaches have been developed. On the one hand, we have developed host materials for PhOLEDs by adjusting their properties (first approach), and, on the other hand, we have been interested in a new generation of OSCs: molecular nanorings (second approach). In a first part, within the framework of developing new host matrices for simplified PhOLEDs so called single-layer, we will present a study of two families of SCOs based on a Donor-spiro-A-acceptor molecular design. This work has enabled to reach the, green and blue PhOLEDs displaying the highest overall performances ever reported in literature. In a second part, after a detailed bibliographical study on the synthesis and on the singular properties of nanorings, we will present our investigations in the field of nanorings. We report herein the synthesis and the study of two families of molecular nanorings constructed with carbazole units. This work allowed us to incorporate for the first time molecular nanorings in organic field-effect transistors in order to study their transport properties

博士
國立臺灣大學
光電工程學研究所
101
In this dissertation, we first demonstrate the preparation of a high-concentration Au nanoring (NRI) water solution and its applications to the enhancement of image contrast in optical coherence tomography (OCT) and the generation of photothermal effect in a bio-sample through localized surface plasmon (LSP) resonance. Au NRIs are first fabricated on a sapphire substrate with colloidal lithography and secondary sputtering of Au, and then transferred into water solution through a liftoff process. By controlling the NRI geometry, the LSP dipole resonance wavelength in tissue can cover the spectral range of 1300 nm for OCT scanning of deep tissue penetration. The extinction cross sections of the fabricated Au NRIs in water are estimated to give the levels of 10-10-10-9 cm2 near their LSP resonance wavelengths. The fabricated Au NRIs are then delivered into pig adipose samples for OCT scanning. It is observed that when resonant Au NRIs are delivered into such a sample, LSP resonance-induced Au NRI absorption results in a photothermal effect, making the opaque pig adipose cells transparent. Also, the delivered Au NRIs in the intercellular substance enhance the image contrast of OCT scanning through LSP resonance-enhanced scattering. By continuously OCT scanning a sample, both photothermal and image contrast enhancement effects are observed. However, by continually scanning a sample with a low scan frequency, only the image contrast enhancement effect is observed. We also demonstrate two fabrication methods to produce Au NRI solution with LSP resonance wavelength below 900 nm. Then, the structure of Au NRIs on SiN nanopilars are demonstrated, which can be used for on-substrate bio-conjugation of Au NRIs. Next, The on-substrate fabrication of bio-conjugated Au NRI solution with the LSP resonance wavelength in the 1200-1300 nm range is demonstrated. Also, the effects of photothermal therapy through LSP resonance-induced absorption enhancement are illustrated by applying the bio-conjugated Au NRIs to human liver cancer cells and illuminating the cells with laser of 1315 nm in wavelength. The Au NRI fabrication is based on the techniques of nano-imprint lithography and metal secondary sputtering. The procedure for on-substrate surface modification of Au NRI leads to a high production yield of bio-conjugated NRI. The threshold levels of the local laser intensity for injuring cancer cells based on the LSP resonances of Au NRIs of two different samples are determined.

碩士
遠東科技大學
電機工程研究所
99
We use parallelized Three-Dimensional Finite-Difference Time-Domain Method to analyze the interaction of polarized visible light with a gapped silver nanoring, try to establish a mechanism to control the intensity of surface plasmon. The gapped silver nanoring is constructed from a toroid of which size is 20nm in diameter and the radius of the cross section is 5 nm. The gap is created by removing an arc of 60-degree angle. The double-gapped nanoring has two gaps at opposite positions. Under the polarized-fixed visible light, we turn around the gapped nanoring and calculate the absorption variation with different gap positions. Based on the symmetry of Maxwell’s equations, it is expected that the absorption of the single gapped nanoring should be the same as the gap is at 2, 4, 8 and 10 o’clock. However, under 600nm wavelength, there are only two absorption maxima occurred when the gap is at 2 and 10 o’clock respectively. It might be explained as the excitation of higher order of multipoles, say, toroid multipoles. If the wavelength is changed to 400nm, the absorption is normal except that it has a less absorption when the gap is at 6 o’clock. For a double-gapped nanoring, the results conform to the symmetry of expectation, but the situations of maximal absorptions are quite different with wavelengths. Under 400nm wavelength, the maxima are happened when the gaps are at 3 and 9 o’clock, but it is changed to 6 and 12 o’clock if the wavelength is tuned to 600nm. The reason why the maxima have a 90-degree transformation is because of the coupling effects between two separated arcs. Overall, polarization and wavelength of incident light both have influences on the absorption of gapped silver nanorings, however, the generation of surface plasmon is more sensitive to the direction of polarization.

碩士
國立彰化師範大學
光電科技研究所
101
In this work, a method to control over the vortex state (flux-closure state) nucleation and annihilation field in asymmetric Permalloy (Py) rings are presented. By introducing an inner circle shifted from the center of outer circle by a shift length, samples of asymmetric Permalloy rings with different asymmetric ratios were fabricated by using E-beam lithography, sputtering, lift-off techniques. And We measured by focused magneto-optic Kerr effect magnetometry and OOMMF program to analyze the magnetic reversal behaviors, and the trend of experiment data agree well with simulation results. The vortex nucleation (Hn) and vortex annihilation (Han) fields, analyzed from the simulated and experimental hysteresis loops of 800 and 1000 nm outer diameters, have linear relations to the asymmetric ratio. It was observed that the nucleation field (Hn) and annihilation field (Han) both are proportional to shift length. And we investigate the influence of different inner diameter on magnetic reversal behavior. The both analyzed switching fields from experiment and simulation present a linear relation with the aspect ratio. This relation indicates that the Hn and Han of asymmetric ring arrays are mainly controlled by the shape anisotropy. It is observed that the switching behavior is in agreement with the simulated and experimental results.

博士
國立交通大學
光電工程研究所
102
Plasmonics has become a very critical research in nanophotonics in recent years because of the advance in fabrication, which realizes localized surface plasmon resonance (LSPR) on metal nanoparticles. The design of metal nanostructures is one of the critical aspects of plasmonics. Recently, nanoring (NR) structures have attracted great research interest since such nanostructures can produce high local fields arisen from strong coupling of inner and outer surface plasmons. In addition, they provide an additional electric field in the cavity region of the ring structure, which is particularly beneficial for practical applications that need high volumes of enhanced fields such as sensing application. In this thesis, we focus on design optimization of structural parameters of the gold NR structure including ring width, slab thickness, and aspect ratio for high local electric field enhancement and high sensitivity to surrounding media. For ring width design, we experimentally demonstrate the index sensitivity of bonding mode in gold NR can be improved by broadening the ring width. High sensitivity of 691 nm per refractive index unit is obtained for NRs with 199 nm ring width. For slab thickness design, the enhancements of electric field intensities at the inner and outer ring surfaces when reducing the slab thickness are investigated. This result renders a useful design principle to fabricate such nanoparticles with a highly enhanced field for sensing application. For aspect ratio design, the disc- and hole-like optical properties of high-aspect-ratio gold NR for longitudinal and transverse polarizations are found, which exhibit stronger field intensity enhancements at the outer and inner ring surfaces respectively. And we find that bonding modes show increased surface sensitivities when enlarging the aspect ratio of gold NR in biosensing experiment. In addition, for probing the near-field interaction of bonding modes, we investigate the optical properties of gold NR dimers particularly. As the gold NR particles approach each other, a very strong surface plasmon coupling in the gap region of gold NR dimers is observed, whose field intensity at the gap distance of 10 nm is enhanced 23% compared to that for gold nanodisk (ND) dimers with the same diameter. Furthermore, this coupling causes exponential increase in sensitivity to refractive index of surrounding medium with decreasing the gap distance. Compared with coupled dipole mode in gold ND dimers, coupled bonding mode in gold NR dimers shows higher index sensitivity. Via structure optimization of gold NRs, we expect that gold NR structure can serve as highly sensitive components of plasmonic sensor for the development of medical diagnosis, monitoring of diseases and drug discovery in the future.

碩士
國立臺灣大學
光電工程學研究所
102
A spectral-domain optical coherence tomography (OCT) system with a light source of ~200 nm in spectral width to achieve the depth and lateral resolutions of ~2 and <4 microns, respectively, is built. This OCT system is used for scanning two kinds of human oral cancer cells (SCC4 and SAS) with applied Au nanorings (NRIs). The localized surface plasmon (LSP) resonance behavior of the Au NRIs, which results in strong scattering of the Au NRIs for OCT imaging, is well controlled such that the long- and short-wavelength halves of the OCT source spectrum have different LSP resonance strengths. Based on this spectral distribution, the spectroscopic operation of the OCT system can lead to the different imaging intensities of the Au NRI distribution in the cell solution between the long- and short-wavelength images. OCT scans are performed at four stages of cell solution, including those before the application of Au NRIs, after the application of Au NRIs, after the washout of the Au NRIs not adsorbed or internalized by the cells, and after the etching of the Au NRIs not internalized by the cells. From the OCT images, particularly the differences between the long- and short-wavelength images in the spectroscopic operation, one can identify the adsorbed and internalized Au NRIs by the cells. It is found that with antibody linkage to the Au NRIs, the Au NRI adsorption and internalization efficiencies become higher.

碩士
國立交通大學
光電工程學系
99
Localized surface plasmon mode could be induced by electromagnetic wave in metal nanostructures. When these nanostructures come in close, LSPR modes are strong coupling, leading to the electric field concentrated and enhanced in the gap of the nanostructures. In this thesis, we demonstrate a gold nanoring dimer structure design and well investigated the corresponding optical properties with varying gap sizes. Compare to typical nanoparticle dimer, nanoring dimer with more and stronger electric field distributions of LSPR bonding mode leads to better sensing applications. At first, the extinction spectra and related LSPR mode profiles of nanodisk and nanoring dimers with varying gap size are simulated and characterized by finite element method. And real devices with different gap sizes are fabricated by series of nano-fabrication process. We observed a red shift of LSPR modes and the enhanced electric field in the gap with decreasing gap size in longitudinal polarization for both nanodisk and nanoring dimers due to LSPR mode coupling. Moreover, the electric field intensity is stronger in nanoring dimer of which the sensitivity reaches to 1076 nm/RIU with gap size of 10 nm in simulation, while the sensitivity is only 901 nm/RIU for nanodisk dimer. In our experiment, high sensitivity of 663 nm/RIU for nanodisk dimer with gap size of 47 nm is obtained, which is better than the sensitivity of 531 nm/RIU for nanodisk dimer with gap size of 28 nm. We promise that it has more potential in nanosening such as protein, DNA, or toxic chemical molecule detections.

Magnetic nanorings are the object of increasing scientific interest because they possess the vortex (stray field free) state which ensures lower magnetostatic interactions between adjacent ring elements in high packing density memory devices. In addition, they have other potential applications such as single magnetic nanoparticle sensors, microwave-frequency oscillators and data processing. The stabilization of magnetization state, types of domains and domain wall structures depends on the competing energies such as magnetostatic, exchange and anisotropy. The nucleation/ pinning of domain walls depends on the local inhomogeneity in shape such as roughness, notches etc, which play an important role in stabilizing domain configurations that can be controlled by magnetic field/spin polarized current etc. The information gained by the study of magnetization reversal in the nanoring devices could help in understanding the possible stable magnetization states, which can be incorporated into the development of magnetic logic and recording devices in a NR-based architecture. The magnetization reversal and the stable states in the symmetric cobalt nanorings (NRs) attached with nanowires (NWs) (at diametrically opposite points), is studied through magnetoresistance (MR) measurements by application of in-plane magnetic field (H). Here, a strong in-plane shape anisotropy is introduced in cobalt thin films by patterning them into NR and NWs. The presence or absence of a DW in the device is detected utilizing the AMR property of the material, where the presence of DW leads to a decrease in the resistance of the probed section of the device. It is demonstrated that the magnetization reversal of the device with smaller width, proceeds through four distinct magnetization states, one of these is the stabilized vortex state that persists over a field range of 0.730 kOe. The effect of width (from 70 nm to 1 µm) and diameter (from 2 µm to 6 µm) on the switching behavior is demonstrated. The magnetization states observed in the MR measurements are well supported by micromagnetic simulations. A statistical analysis of switching fields in these devices was demonstrated by histogram plot (of switching counts) to understand the repeatability and reproducibility of switching characteristics. In addition, the magnetization reversal of permalloy NR is also studied by MR experiment when two NWs are attached to it in two different configurations. It has been demonstrated that a vortex state can be stabilized if the NWs are attached in a way that they are at an obtuse angle with respect to each other (type-II device) which is not the case if the NWs are attached at diametrically opposite points (type-I device). This occurs because the NWs reverse at different fields as they are asymmetric with respect to applied magnetic field at every angle. The angular dependence study of the magnetization states indicates that the vortex state could be always stabilized in the type-II device irrespective of the direction of in-plane applied magnetic field while it is not the case in type-I device. The experimental observations are in good agreement with micromagnetic simulations performed on similar device structures. Further, in the last part of the thesis, the magnetization reversal of geometrically engineered cobalt NR (of width 80 nm) devices are studied by application of H. Two types of cobalt nanoring devices were fabricated. In type-1 devices the NR is attached with two nanowires (NWs) at diametrically opposite positions. In type-2 devices the NR is attached with one NW, whose other end is attached to a 5 µm x 5 µm square pad. In type-2 device, the pad reverses first, thus causing the generation of a DW at the junction of the nucleation pad and the NW. The device type-2 possesses five distinct magnetization states, one of these is the vortex state. Easy nucleation of domain walls (DWs) results in a decrease of switching field corresponding to the reversal of the nanowire. This leads to an increase in the range of fields, where the vortex state exists. In addition, angular dependence of the switching behavior indicates that the vortex state can be stabilized at all in-plane orientations of H. This occurs because of the fact that symmetry was broken due to the presence of single domain wall pinning center which was the junction of the NR and NW. The results of our micromagnetic simulations are in a good agreement with the experimental results. These results are important to understand the role of NWs which allows the formation of vortex state at every angle of the in-plane H. In type-1 device, the simulation shows that when the field is applied at any angle away from the axis of the NW, the vortex state cannot be stabilized. The width dependent study of switching fields indicates, that the switching fields decrease with increasing the width of NR devices due to a reduction of the demagnetization field.

碩士
國立交通大學
光電工程學系
101
The high tunable localized surface plasmon resonance of nanoring has been investigated with different ring widths. The strong electric field intensity enhancement of bonding mode is provided by the plasmon coupling between the inner and outer surface of nanoring, which is suitable for biological sensing, nanotrapping and field enhanced spectroscopy. In this thesis, we propose the elliptical gold nanoring for studying the aspect ratio effect of such hybridized nanostructure. The resonance wavelength, mode profile and charge distribution of elliptical gold nanoring has been studied by simulation and experiment with different aspect ratios and polarizations. The results show that the tunability of the peak wavelength and the electric field intensity enhancement are improved by controlling the aspect ratio. Furthermore, the index sensing properties of elliptical gold nanoring were compared with that of elliptical gold nanodisc. The aspect ratio effect on index sensing was observed and the unique plasmonic properties under transverse polarization have been completely studied.

碩士
國立交通大學
光電工程研究所
104
When the light illuminates metallic nanoparticle and is satisfied the conditions of local surface plasmon resonance (LSPR), the light will be confined in subwavelength scale, and the intensive enhancement of localized field around the metallic nanoparticles occurs. Therefore, these metallic nanoparticles can be served as plasmonic devices to achieve manifold applications including bulk refractive index sensing, chemical sensing, and trapping. Usually, the plasmonic devices are made of metals such Au or Ag because their high carrier concentration can intensively interact with light. However, suffering from high interband and intraband transition in optical frequencies, metal plasmonic devices operated in optical frequencies result in large losses. Furthermore, the high carrier concentrations in metals also lead seriously radiative losses. Moreover, the transparent conducting oxides (TCOs) can be suitable candidate for low-loss plasmonic materials in NIR region due to lower interband and intraband transition losses. In this thesis, I fabricated the AZO nanoring arrays by e-beam lithography to pattern the nanoring arrays and radio frequency (RF) magnetron sputtering system to deposit AZO thin film. The simulation of LSPR properties by COMSOL software utilized the dielectric function retrieved from AZO thin film. And I demonstrated highly consistent extinction spectra in simulation and experiment. Moreover, the AZO nanoring arrays have been utilized to achieve surface-enhanced infrared spectroscopy. Therefore, the AZO nanoring arrays perform high potential in chemical sensing.

碩士
國立臺灣大學
光電工程學研究所
104
The more effective inactivation of oral cancer cell SAS through the combination the photothermal therapy (PTT) and photodynamic therapy (PDT) effects based on the localized surface plasmon resonance (LSPR) around 1064 nm in wavelength of Au nanoring (NRI) under femtosecond (fs) laser illumination is demonstrated. The PTT effect is caused by the LSPR-enhanced absorption of Au NRI. The PDT effect is generated by linking Au NRI with the photosensitizer of AlPcS for producing singlet oxygen through the LSPR-enhanced two-photon absorption (TPA) excitation of AlPcS. The laser threshold intensity for cancer cell inactivation with the applied Au NRI linked with AlPcS is significantly lower, when compared to that with the Au NRI not linked with AlPcS. The comparison of inactivation threshold intensity between the cases of fs and continuous laser illuminations at the same wavelength and with the same average power confirms the crucial factor of TPA under fs laser illumination for producing the PDT effect.

博士
國立清華大學
工程與系統科學系
105
In the past decades, nanotechnology has rapidly progressed because enormous possibilities have been unlocked to manipulate materials toward high performance devices. Most works have focused on miniaturizing devices on two-dimensional (2D) surface by thin film technology. In the presented thesis, we adapted a quasi-3D system to reclaim volume from the vertical space and create directive arrangement for materials on 2D surface. The properties of material resident in the nanospace were strongly governed by the vertical and nanoscaled architectures, making the systems dramatically different from their thin film and bulk homologue. In the first part, I introduce a facile route to create crystalline colloidal monolayer (CCM) via air/water interfacial self-assembly, which intrigues researches and engineers by the wafer-scaled nanofabrication without high capital costs. Here, I carefully studied the 2D colloidal system and made efforts to build a diffractive system that can non-invasively monitor the self-assembly process, with nanoscale precision, for batch-to-batch stability. With the assistance of stable and superior self-assembled colloidal array, the desired periodic nanostructure was realized by nanosphere lithography. The second part is the application of CCM derived nanostructured array, related to light management, I use self-aligned nanoring array to enhance the numbers of hot-spots in vertical direction. A high-density-hotpots substrate is highly desirable in practical uses of surface enhanced Raman spectroscope (SERS). Upon locating a nanopillar in each nanowell, a nanohole network, nanoring and nanodisc was formed after gold thin film deposition and producing more edges per unit cell compared to simple nanowell or nanohole structures. Finite-difference time-domain (FDTD) simulations and SERS measurements both confirm that the magnitude of SERS signals can be enhanced compared to simple 2D design. In addition, the developed nanofabrication allowed people to fine tune the geometries of nanostructure, which affect the adsorption spectrum of the substrate. I purposely tune the resonance peaks to fit the incident laser wavelength for each substrate to their optimum condition and further confirmed the enhanced SERS sensitivity is from the enhanced numbers of hot-spots per unit cell.

碩士
國立臺灣大學
光電工程學研究所
102
Au nanorings (NRIs), which have the LSP resonance wavelength around 1058 nm, either with linked antibody (NRI-AB) or without antibody (NRI-control), are applied to SAS oral cancer cell for cell inactivation through the localized surface plasmon (LSP)-induced photothermal effect when it is illuminated by a laser of 1065 nm in wavelength. Various incubation times after the application of Au NRIs to cell are considered for observing the variations of cell uptake of Au NRI and hence the threshold laser intensity for cancer cell inactivation. In each case of incubation time, the SAS cell is washed for evaluating the Au NRI number per cell adsorbed and internalized by the cells. Also, the Au NRIs adsorbed (remaining on cell membrane) are etching with KI/I2 to evaluate the Au NRI number per cell internalized by the cells. The threshold laser intensities before washout, after washout, and after KI/I2 etching are calibrated from the circular area sizes of inactivated cells around the illuminated laser spot center under the illuminations of various laser power levels. The adsorbed and internalized Au NRIs per cell are obtained from inductively coupled plasma mass spectrometry measurements of the flushed solution in the KI/I2 etching process and the remaining cell solution, respectively. By using Au NRIs with antibody, it is found that the internalized Au NRI number per cell increases with incubation time. However, the adsorbed Au NRI number per cell reaches a maximum at 12 hrs in incubation time. The cell uptake behaviors of Au NRIs without antibody are similar to those with antibody. Nevertheless, the NRI numbers per cell are significantly smaller. Meanwhile, the incubation time for the maximum adsorbed NRI number per cell is delayed to 20 hrs. By comparing the variation of threshold laser intensity for cell inactivation, it is found that the adsorbed NRIs can cause more effective cancer cell inactivation, when compared with the internalized NRIs. The minimum threshold laser intensities after cell solution washout in either case with or without antibody are observed before KI/I2 etching under the aforementioned incubation time conditions of maximum adsorbed NRI number per cell.

abstract: III-Nitride nanostructures have been an active area of research recently due to their ability to tune their optoelectronic properties. Thus far work has been done on InGaN quantum dots, nanowires, nanopillars, amongst other structures, but this research reports the creation of a new type of InGaN nanostructure, nanorings. Hexagonal InGaN nanorings were formed using Metal Organic Chemical Vapor Deposition through droplet epitaxy. The nanorings were thoroughly analyzed using x-ray diffraction, photoluminescence, electron microscopy, electron diffraction, and atomic force microscopy. Nanorings with high indium incorporation were achieved with indium content up to 50% that was then controlled using the growth time, temperature, In/Ga ratio and III/N ratio. The analysis showed that the nanoring shape is able to incorporate more indium than other nanostructures, due to the relaxing mechanism involved in the formation of the nanoring. The ideal conditions were determined to be growth of 30 second droplets with a growth time of 1 minute 30 seconds at 770 C to achieve the most well developed rings with the highest indium concentration.
Dissertation/Thesis
M.S. Materials Science and Engineering 2012

碩士
國立臺灣大學
光電工程學研究所
102
We first study the dependencies of SCC4 cancer cell uptake efficiency on Au nanoring (NRI) size, incubation time, and Au NRI concentration. Then, we perform the experiment of localized surface plasmon (LSP)-induced photothermal inactivation of SAS cancer cells with different Au NRI sizes and concentrations through the illumination of a laser of a wavelength close to the LSP resonance peaks of the NRIs. In the study of NRI uptake efficiency, which includes the adsorption and internalization efficiencies of NRI by SCC4 cells, it is found that the uptake efficiency becomes significantly higher when the outer diameter is smaller than ~100 nm and antibody is linked to NRI. By varying the incubation time, it is found that the uptake of SCC4 cells reaches a maximum level at 8 hours and then starts effective exocytosis. Regarding the uptake dependence on NRI concentration, it is found that the uptake efficiency increases significantly when NRI concentration reaches a threshold level. In the inactivation study of SAS cancer cells with bio-conjugated Au NRI, it is found that the small-sized NRI has higher uptake efficiency and always has a stronger photothermal effect or higher cancer cell inactivation efficiency, even though the concentration of the small-sized NRI is slightly smaller and its LSP resonance peak is slightly further away from the laser wavelength, when compared with the large-sized NRI. The stronger photothermal effect of a small-sized NRI is partly attributed to its relatively larger absorption cross section with respect to scattering cross section. For either SCC4 or SAS oral cancer cells, the uptake and inactivation efficiencies are higher when Au NRIs of <100 nm in outer diameter are used.

碩士
國立臺灣大學
光電工程學研究所
105
The methods of cell perforation and preheating are used for increasing cell uptake efficiency of Au nanorings (NRIs), which have the localized surface plasmon (LSP) resonance wavelength around 1064 nm, and photosensitizer, AlPcS, and hence enhancing the cell damage efficiency through photothermal (PT) and photodynamic (PD) effects. The perforation and preheating effects are generated by illuminating an off-focus 1064-nm femtosecond (fs) laser and an off-focus 1064-nm continuous (cw) laser, respectively. Cell damages are produced by illuminating cell samples with an on-focus 1064-nm cw laser for producing PT effect, an on-focus 1064-nm fs laser for producing both PT and PD effect, and an on-focus 660-nm cw laser for producing PD effect. The results show that under various conditions of pre-washout, post-washout, and post-etching, with either perforation or preheating process, cell uptake and hence cell damage efficiencies are enhanced. Generally, perforation is more effective in the aforementioned functions, when compared with preheating, under the current experimental conditions.

Unconventional nanofabrication techniques; both those which have been newly developed and those under development, had brought inexpensive, facile, yet high quality means to fabricate nanostructures that have feature sizes of less than 100 nm in industry and academia. This dissertation focuses on developing unconventional fabrication techniques, building studying platforms, and studying the mechanisms behind them. The studies are divided into two main facets and four chapters. The first facet, in Chapter II and Chapter III, deals with the research and development of different nanofabrication techniques and nanostructures. These techniques include litho-synthesis, colloidal lithography, and photolithography. The nanostructures that were fabricated by these techniques include the metal nanoparticle arrays, and the self-assembled CdSe nanoring arrays. At the same time, the dissertation provides mechanisms and models to describe the physical and chemical nature of these techniques. The second area of this study, in Chapter III to Chapter V, presents the applications of these nanostructures in fundamental studies, i.e. the mechanisms of plasmon enhanced fluorescence and photo-oxidation kinetics of CdSe quantum dots, and applications such as molecular sensing and material fabrication. More specifically, these applications include tuning the optical properties of CdSe quantum dots, biomodification of CdSe quantum dots, and copper ion detection using plasmon and photo enhanced CdSe quantum dots. We have successfully accomplished our research goals in this dissertation. Firstly, we were able to tune the emission wavelength of quantum dots, blue-shifted for up to 45 nm, and their surface functionalization with photo-oxidation. A kinetic model to calculate the photo-oxidation rates was established. Secondly, we established a simple mathematical model to explain the mechanism of plasmon enhanced fluoresce of quantum dots. Our calculation and experimental data support the fluorescence resonance energy transfer (FRET) mechanism between quantum dots and the metal nanoparticles. Thirdly, we successfully pattered the CdSe quantum dots (diameter ~4 nm) into nanorings with tunable diameters and annular sizes on different substrates. We also established a physical model to quantitatively explain the mechanism with the forces that involved in the formation of the nanorings.

碩士
國立中正大學
化學工程所
95
This research was studied on preparation of carbon nanotube ring by simple thermal oxidation and ultrasonic treament. Oxidized single-walled carbon nanotube at different temperature, then suspended in isopropyl alcohol using ultrasonic sonication with different time. By the experiment results, as oxidation temperature was 470℃ for 15mins and ultrasonic sonication time was 4 hr, the highest yield of SWNT ring was 40%. Most SWNT rings have the diameter in the range of 200-500nm and the width in the range of 10-30nm. We observed the width of SWNT rings are larger than 40nm , named this kind of SWNT ring as 3D ring. The 3D rings were about 15% of all SWNT rings. We also succeed in preparation of the MWNT rings by the same method. We discussed the mechanism of SWNT ring. In the oxidation process, the pentagonal carbon ring and the heptagonal carbon ring occurred dislocation, then SWNT would bend , coil up. In the ultrasonic process, the cavitation produced large pressure in liquid, then liquid would compress the incomplete SWNT ring. The strong tube-tube van der Waals attraction made SWNT ring tighter. SWNT rings formed by individual ropes of SWNT coiling up.

This thesis discusses experimental research and theoretical analysis on exploring the physics and techniques of manipulation of magnetization states of ferromagnetic nanorings in both homogeneous and non-homogeneous applied magnetic field. Magnetization states and their switching processes are fundamental properties of magnetic systems. The ring shape is particularly interesting because of the existence of the closed-flux vortex state, which can be used to encode binary information. The understanding and control of the magnetization switching of ferromagnetic nanorings could lead to new designs of practical magnetic data storage devices. The work in this thesis is grouped into three main activities: theoretical analysis and micromagnetic simulation, fabrication techniques, and characterization of magnetization switching by applied magnetic field. Ferromagnetic rings with different geometric parameters were fabricated by electron beam lithography (EBL), electron beam evaporation and lift-off techniques. EBL patterning on double layer photo resist improved lithography and lift-off resolution. The experiments with applied homogeneous and non-homogeneous fields were able to manipulate the ferromagnetic nanorings through different magnetic configurations. The key accomplishment of this work is we experimentally achieved direct switching between two magnetic vortex states of opposite circulation of magnetization, by using an applied azimuthal (circular) Oersted magnetic field. Such field was generated by applying current through the center of a ring using a platinum atomic force microscopy tip. We used magnetic force microscope imaging to demonstrate the controllability of magnetic switching from onion state to vortex state and for the first time, direct switching between two opposite vortex states. Moreover, we investigated the switching mechanisms associated with nucleation, annihilation, and propagation of domain walls. The magnetic switching properties were found to be sensitive to the ring geometrical parameters. Smaller rings require less circular field to complete the switching than bigger rings. Asymmetric rings require less circular field to complete the switching than symmetric rings with the same dimensions. Theoretical analysis and micromagnetic simulations were conducted on symmetric and asymmetric nanorings, with the purpose of helping us better understand the physics behind the experimental results. Those systematic studies investigated the energy and stability of different magnetization states, the switching field required as a function of the ring geometric designs, as well as switching mechanism and the evolutions among different magnetic states, in both in-plane and azimuthal Oersted magnetic fields. We found the simulations results are in a good agreement with the characterization results.

Plasmons, the collective electronic oscillations of metallic nanoparticles and nanostructures, are at the forefront of the development of nanoscale optics. Metallic nanostructures with their geometry-dependent optical resonances are a topic of intense current interest due to their ability to manipulate light in ways not possible with conventional optical materials. As optical frequency nanoantennas, reduced-symmetry plasmonic nanoparticles have light-scattering properties that depend strongly on geometry, orientation, and variations in dielectric environment. Particularly fascinating aspect of these systems is the recently realized possibility of creating optical frequency “magnetic plasmon” responses of comparable magnitude to the “electric plasmon” response. It is of our central interest to understand better the plasmonic system so as to manipulate the energy transport mechanism. With the much more advanced numerical calculations, and based on the Finite Element Method (FEM) and Finite-Difference Time-Domain (FDTD) method, we are now able to study various kinds of nanostructures for different interesting optical properties. With the help of FDTD, we show the geometry dependent dissipation rate in different nanosystems. We brought up a new damped harmonic oscillator model to account for the observed difference. We show that our new model better completes the full map of the energy dissipation mechanism, and the predicted outcome agreed very well with the FDTD calculations. Elliptical nanorings were investigated by applying both FEM and FDTD methods. The mulitiple plasmonic resonaces exhibited by elliptical nanorings and the well tunability of the nanosystem make elliptical nanorings very interesting. Different features can be realized by controlling the aspect ratios of the elliptical nanorings. We show another interesting nanostructures, light bending nanocup as well. Due to its unique light scattering properties, nanocup is a very promising candidate in solar cell applications. We studied more about its light redirection properties with the presence of a dielectric substrate and its sensitivity to the subtle geometry differences. Plasmonic heptamer has been shown to possess an intriguing Fano resonance due to the interference of its hybridized subradiant and super-radiant modes. Neighboring fused heptamers can support magnetic plasmons due to the generation of antiphase ring currents in the metallic nanoclusters. We use such artificial plasmonic molecules as basic elements to construct low-loss plasmonic waveguides and devices. The manipulation of magnetic plasmons in heptamer interconnects can further be expanded to more complex systems, for example, by integrating more optical paths to achieve multiple input and output plasmonic networks. With their compact dimensions, outstanding low-loss propagation characteristics, and range of functionalities, magnetic plasmon-based devices based on these structures should be key to the further development of high- performance energy transport components in informa- tion processing and data storage applications.

碩士
國立交通大學
材料科學與工程學系
101
This thesis describes two main subjects: (I) the block-copolymer mediated ultrasonic synthesis of novel Au branched nanorings and (II) the morphology dependent Surface plasma resonance (SPR) and the application of surface enhanced Raman scattering (SERS) in detecting malachite green molecules. Compared to the structures with a dense solid morphology with smooth surface, the branched surface and ringed morphology presented in the prepared novel gold branched nanorings can effectively provide larger specific surface area and higher chemical activity even when they are casted into films or bulk. In addition, the distinct nanostructures provide unusual morphology-dependent SPR and SERS properties completely differing from other metallic ones are interesting and valuable for fundamental researches and sensing applications. Regarding the synthesis strategy, block-copolymers frequently perform multiple functions in the chemical reactions, for instance, acting as soft templates, shape directing agents, surfactants, and reductants. Ultrasonic irradiation via liquid media is known as a facile and effective treatment for providing energy and thus activating or enhancing sonochemical syntheses of metallic nanostructures. In this work, by coupling the designating features of the block-copolymer (Pluronic P84) and ultrasonic irradiation, the Au branched nanorings were successfully synthesized. The present facile process is material-economized, pollution-limited, non-toxic, low-cost and hard-template- and substrate-free. In addition, the SERS raised from the casted films of the Au branched nanorings is successfully applied to trace a very low concentration (0.5 ppb) of toxic malachite green molecules. The extraordinary SERS sensing ability well satisfy the measurement requirement of an acceptable maximum level of 2 ppb published by European commission, indicating the great potential on practical applications.

碩士
國立中正大學
化學暨生物化學研究所
105
Using contrast agent (CA) is a common way to shorten the detection time and improve the contrast of magnetic resonance imaging (MRI). Nowadays commercial MRI CAs are used for either T1 or T2 imaging.1,2A T1 and T2 dual modality CA was synthesized in this thesis. Because Gd is a common material for T1 CAs and Fe for T2 CAs, we use molar ratio Gd/Fe=1 as reagent to synthesize porous nanoparticles, with particle size about 50 nm. Our CA gets better contrast than commercial CAs when concentrations between 0.015 mM and 0.062 mM (T1 weight image), 0.031 mM and 0.125 mM (T2 weight image). Several experiments have been carried out to study the mechanisms of our CA. The result is different from the prediction according to theory, because the structure of our CA is different from the model, so we need to use an advanced theory modified the spin quantum number (S) to fit the result in our experiment. In conclusion that the contrast of our CAs is mainly from Gd, while Fe only contributes to the porous structure.

碩士
國立中正大學
化學工程所
96
This research was tried to synthesize single-walled carbon nanotube array by chemical vapor deposition method using alcohol as carbon source and changed sputtering time, catalyst species and reduction gas. Using NH3 as reduction gas can synthesize multi-walled carbon nanotube by Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The length of CNTs decreased with shortening the time of sputtering catalyst and the diameter of CNTs also decreased. The Mo-Co catalyst was annealing in air at 500℃, then successfully grew single-walled carbon nanotube array in an Ar/H2 stream of 250sccm/50sccm at 850℃ for 30min. By Raman scattering analysis, we can observe peaks at radial breathing mode (RBM) locations and these can proof have single-walled carbon nanotube existence. The single-walled carbon nanotube bundles were also be observed by TEM images, diameters around 2.3nm. Synthesized single-walled carbon nanotubes were used to prepare carbon nanorings. Fist, carbon nanotubes were oxidized at 420℃ and only Mo-Co bimetallic catalyst can remain carbon nanotube. Residual carbon nanotubes were became carbon nanorings by ultrasonic sonication for 4hr and diameter of carbon nanoring was 330nm. The 3D rings can be found and diameter of rings were 205nm and width of rings were 50nm.

碩士
遠東科技大學
機電光系統研究所
98
We numerically study the interactions of silver nanorings with polarized optical waves, some extraordinary optical properties are unveiled. If the resonant conditions are tuned, the polarization of incident field, inside the nanoring hole, will be reversed by the single silver nanoring due to the surface plasmon resonance, thus, the nanoring hole becomes a region of which permittivity is negative. Put two identical silver nanorings closely, there are two nodes happened between nanorings. It indicates that there is a very steep gradient of electric field and quasi-standing waves exist between nanorings. If many silver nanorings are lined up, the holes of the nanorings will form a negative permittivity chamber. The closer the center of the chamber, the more ideal the polarization is reversed.

碩士
中原大學
生物醫學工程研究所
100
Fluorescent gold nanoclusters (FANCs) have been considerably attracted due to its excellent biocompatibility and photostability. In this thesis we introduce a novel structure of red fluorescent AuNCs with emission peak at 613 nm, i.e. a rice-liked structure (nanorice) with length of 176.66 nm under the transmission electron microscopy (TEM). Each nanorice is assembled from hundreds of AuNCs. When incubating the nanorice under high temperature (95°C), nanorice began to disassemble into mono-dispersed AuNCs at size of 2.77 nm in diameter accompanying with quench of fluorescence. However, the fluorescence was recovered again when fluorescent AuNCs began reassembling back to nanocrice which was evidenced by TEM images. We further developed a phase transfer method for improving the water solubility of such fluorescent gold nanorice. In addition, hydrophobic nanoparticles (ex: iron oxide or gold nanoparticles) and fluorescent AuNCs could form nanocomposites by using the aurophilic assembly interaction. Either fluorescent gold nanorice or it nanocomposits could became water-soluble upon sequential suface modification of cetyltrimethyl ammonium bromide and polyoxyethylene 40 stearate. In conclusion, the novel fluorescent gold nanocomposites not only have photoluminescent features but also offer additional functionality from nanoparticles, giving great potential application in biomarker and biomedical application in the future.

In this thesis two issues in nanotechnology have been addressed. The first is the comprehensive characterization of engineered nanomaterials prior to their examination in toxicology and environmental studies. The second is the development of a method to produce nanostructure arrays over large areas and for low cost. A major challenge when assessing nanomaterial’s risks is the robust characterization of their physicochemical properties, particularly in commercial products. Such data allows the critical features for biological outcomes to be determined. This work focused on the inorganic oxides that were studied in powdered and dispersed forms as well as directly in consumer sunscreen products. The most important finding was that the commercial sunscreens that listed titania or zinc oxide as ingredients contained nanoscale materials. Cell free photochemical tests revealed that ZnO particles without any surface coating were more active at generating ROS than surface coated TiO2 nanoparticles. These studies make clear the importance of exposure studies that examine the native form of nanomaterials directly in commercial products. The second part of this thesis presents the development of a new method to fabricate gold nanoring and nanocrescent arrays over large areas; such materials have unique optical properties consonant with those described as metamaterials. A new shaped nanosphere lithography approach was used to manipulate the form of silica nanospheres packed onto a surface; the resulting array of mushroom structures provided a mask that after gold evaporation and etching left either golden rings or crescents over the surface. The structures had tunable features, with outer diameters ranging from 200 to 350 nm for rings and crescent gap angles of ten to more than a hundred degrees. The use of a double mask method ensured the uniform coverage of these structured over 1 cm2 areas. Experimental and theoretical investigations of the optical properties of the arrays revealed the optical resonances in the infrared region. Finally, in the course of developing the nanorings, etch conditions were developed to deposit large area arrays of polystyrene nanodoughnuts with diameters from 128 to 242 nm. These non-conductive structures provide an ideal template for further attachment of magnetic of optically emissive nanoparticles.

碩士
國立高雄應用科技大學
化學工程與材料工程系
99
A novel method for the synthesis of as-prepared Ag nanoplates in high yield and the control of their dimensions has been developed. In this method, hexadecyltrimethyl ammonium ions (CTA+) are used as a trace additive in a seed solution for blocking the seed surface to govern the growth direction on nanoplate in the growth pathway, leading to a high-yield production of the Ag nanoplates with mixed morphologies, mainly triangular nanoplates and nanodisks. The spectra of the obtained nanoplate solution showed a highintensity peak attributed to the in-plane dipole resonance and a low-intensity peak at 400 nm. By decreasing the amount of CTA+, the mean edge length of triangular nanoplates could be changed from ~78.7 -~124.8 nm. The in-plane dipole resonance peak corresponding to change in the mean edge length shifted from 630 nm to 785 nm, respectively. The mean edge length of triangular nanoplates could also be lengthened from 70 nm to 148 nm by decreasing the CTA+-adsorbed seed amount. To investigate the practical feasibility of application of the proposed method, the prepared nanoplates were used as a methanol-tolerant electrocatalyst in an oxygen reduction reaction (ORR). An analysis conducted using a rotating ring-disk electrode showed that these nanoplates have high activity towards the ORR and that the electron transfer numbers (n) were 3.85, 3.83, 3.81, and 2.94 for 70 nm, 124 nm, 148 nm nanoplates respectively, and macroscopic Ag electrode, respectively. In the presence of methanol, the corresponding n values of 3.82, 3.81, 3.78, and 2.30 were detected. Despite working in the methanol-tolerant solution, the prepared Ag nanoplates still exhibited high electroactivity and their ORR proceeded via an approaching 4-electron pathway. Hexagonal Ag/Pt nanoplates were prepared via a galvanic displacement reaction in which added K2PtCl4 reacted with Ag nanoplates. The spectra of the obtained nanoplate solution showed a high intensity peak attributed to in-plane dipole resonance. The mean edge length of triangular nanoplates could be changed from 54 nm to 65nm. The in-plane dipole resonance peak corresponding to change in the mean edge length shifted from 600 nm to 700 nm. To investigate the practical feasibility of the proposed method, the prepared nanoplates were used as a methanol-tolerant electrocatalyst in an oxygen reduction reaction (ORR). An analysis conducted using a rotating ring-disk electrode showed that these Hexagonal nanoplates have high activity towards the ORR and that the n values were 3.85 and 3.92 for hexagonal Ag/Pt nanoplates and hollow hexagonal Ag/Pt nanoplates.The prepared hexagonal Ag/Pt nanoplates and hollow hexagonal Ag/Pt nanoplates have excellent activity the kinetic current(ik) were 2.72×10-2mA and 6.38×10-2mA, specific current density(jk) were 2.8×10-2mA cm-2 and 23.74×10-2 mA cm-2, mass activity(jm) were 6.98×10-4 mA μg-1 and 20.1×10-4 mA μg-1, PHO- were 86.4% and 93.22%. However, for hexagonal Ag/Pt nanoplates and hollow hexagonal Ag/Pt nanoplates in the ORR of methanol, the PHO-s were 72.37% and 87.37%. The n values were calculated to be 3.68 and 3.87.This indicates that despite working in the methanol-tolerant solution, the prepared hollow hexagonal Ag/Pt nanoplates still exhibited high electroactivity and their ORR proceeded via an approaching 4-electron pathway. Triangular Ag/Pd/Pt nanorings were prepared via a galvanic displacement reaction in which added Pd(OAc)2 and H2PtCl6 reacted with Ag nanoplates. The spectra of the obtained nanoplate solution show a high intensity peak attributed to the in-plane dipole resonance. The mean edge length of triangular nanoplates could be changed from 160 nm to 177nm. The in-plane dipole resonance peak corresponding to change in the mean edge length shifted. To investigate the practical feasibility of application of the proposed method, the prepared nanoplates were used as methanol-tolerant electrocatalyst in oxygen reduction reaction (ORR). An analysis conducted using a rotating ring-disk electrode show that these Triangular Ag/Pd/Pt nanorings have high activity towards the ORR and that the n values were 3.834 and 3.89 for triangular Ag/Pd/Pt nanorings and triangular Ag/Pt/Pd nanorings.The prepared triangular Ag/Pd/Pt nanorings and triangular Ag/Pt/Pd nanorings have excellent activity the kinetic current(ik) were 2.04×10-2mA and 3.39×10-2mA, specific current density(jk) were 14.28×10-2mA cm-2 and 28.6×10-2 mA cm-2, mass activity(jm) were 6.49×10-4 mA μg-1 and 12.6×10-4 mA μg-1, PHO- were 84.65% and 90.42%. However, for triangular Ag/Pd/Pt nanorings and triangular Ag/Pt/Pd nanorings in the ORR of methanol, the PHO-s were 68.85% and 77.57%. The n values were calculated to be 3.63 and 3.75.This indicates that despite working in the methanol-tolerant solution, the prepared triangular Ag/Pt/Pd nanorings still exhibited high electroactivity and their ORR proceeded via an approaching 4-electron pathway.