Optics has the inherent advantages of parallelism and wide bandwidths in processing information. However, the need to interface with electronics creates a bottleneck that eliminates many of these advantages. The proposed research explores novel optical devices and techniques to overcome some of these bottlenecks. To address parallelism issues we take a specific example of a content-addressable memory that can recognize images. Image recognition is an important task that in principle can be done rapidly using the natural parallelism of optics. However in practice, when presented with incomplete or erroneous information, image recognition often fails to give the correct answer. To address this problem we examine a scheme based on free-space interconnects implemented with diffractive optics. For bandwidth issues, we study possible ways to eliminate the electronic conversion bottleneck by exploring all-optical buffer memories and all-optical processing elements. For buffer memories we examine the specific example of slow light delay lines. Although this is currently a popular research topic, there are fundamental issues of the delay-time-bandwidth product that must be solved before slow light delay lines can find practical applications. For all-optical processing we examine the feasibility of constructing circuit elements that operate directly at optical frequencies to perform simple processing tasks. Here we concentrate on the simplest element, a sub-wavelength optical wire, along with a grating coupler to interface with conventional optical elements such as lenses and fibers. Even such a simple element as a wire has numerous potential applications. In conclusion, information processing by all-optical devices are demonstrated with an associative memory using diffractive optics, an all-optical delay line using room temperature slow light in photorefractive crystals, and a subwavelength optical circuit by surface plasmon effects.

The strong electromagnetic field that is induced at the surface of a plasmonic nanoparticle can be utilized for many important applications, including spectroscopic enhancement and electromagnetic waveguides. The focus of this thesis is to study some of the properties of induced plasmonic fields around metal nanoparticles. Current methodologies for fabricating nanoparticles are discussed, including lithography and colloidal synthesis. This dissertation includes studies on plasmonic driven nanoparticle motion of surface supported gold nanoprisms from a substrate into solution via a femtosecond pulse. The mechanism of particle motion is discussed and the stability of the unprotected nanoprisms in solution is studied. Fundamental plasmonic near-field coupling between two plasmonic nanoparticles is also examined. Experimental results using electron beam lithography fabricated samples are used to explicitly describe the plasmonic coupling between dimers as a function of the nanoparticle size, shape, and orientation. These variables are systematically studied and the dependence is compared to mathematically derived functional dependencies in order to model and predict the effects of plasmonic coupling. As an extension, the coupling between plasmonic nanoparticles is shown in a common application, surface enhanced Raman scattering. The final chapter is devoted to an investigation of the nature of nanocatalysis, homogeneous and heterogeneous, for several reactions using metal nanoparticles.

The work presented in this dissertation suggests novel design of chemical plasmonic sensors which have been developed based on Localized Surface Plasmon Resonance (LSPR), and Surface-enhanced Raman scattering (SERS) phenomena. The goal of the study is to understand the SERS phenomena for 3D hybrid (organic/inorganic) templates and to design of the templates for trace-level detection of selected chemical analytes relevant to liquid explosives and hazardous chemicals. The key design criteria for the development of the SERS templates are utilizing selective polymeric nanocoatings within cylindrical nanopores for promoting selective adsorption of chemical analyte molecules, maximizing specific surface area, and optimizing concentration of hot spots with efficient light interaction inside nanochannels. The organic/inorganic hybrid templates are optimized through a comprehensive understanding of the LSPR properties of the gold nanoparticles, gold nanorods, interaction of light with highly porous alumina template, and the choice of physical and chemical attributes of the selective coating. Furthermore, novel method to assemble silver nanoparticles in 3D as the active SERS-active substrate has been demonstrated by uniform, in situ growth of silver nanoparticles from electroless deposited silver seeds excluding any adhesive polymer layer on template. This approach can be the optimal for SERS sensing applications because it is not necessary to separate the Raman bands of the polyelectrolyte binding layer from those of the desired analyte. The fabrication method is an efficient, simple and fast way to assemble nanoparticles into 3D nanostructures. Addressable Raman markers from silver nanowire crossbars with silver nanoparticles are also introduced and studied. Assembly of silver nanowire crossbar structure is achieved by simple, double-step capillary transfer lithography. The on/off SERS properties can be observed on silver nanowire crossbars with silver nanoparticles depending on the exact location and orientation of decorated silver nanoparticles nearby silver nanowire crossbars. As an alternative approach for the template-assisted nanostructure design, porous alumina membrane (PAM) can be utilized as a sacrificial template for the fabrication of the nanotube structure. The study seeks to investigate the design aspects of polymeric/inorganic hybrid nanotube structures with plasmonic properties, which can be dynamically tuned by external stimuli such as pH. This research suggests several different organic/inorganic nanostructure assemblies by various template-assisted techniques. The polymeric/inorganic hybrid nanostructures including SERS property, pH responsive characteristics, and large surface area will enable us to understand and design the novel chemical plasmonic sensors.

The literature on nanomaterials has been flooded with new shapes, sizes, and compositions of nanostructures. The process of developing and characterizing these particles has been broadly accomplished and many interesting and promising properties have been revealed for application in current and developing technologies. In particular, the phenomenon of surface plasmon resonance seen in metallic gold and silver nanoparticles has drawn substantial interest. It has been established that the electromagnetic fields surrounding plasmonic particle surfaces can influence the properties of nearby systems, causing them to experience effects such as enhanced absorption and emission of light or drastically increased conductivity. For this reason, plasmonic nanoparticles are being applied to an endless number of applications for new materials. This thesis investigated the effects of silver nanocube (AgNC) arrays on the photophysical properties of poly(paraphenyleneethynylene) (PPE) fluorescent polymers, a particularly relevant material to the applications of organic-electronics. AgNCs were selected because of their particularly strong plasmonic field, which is enhanced at the sharp features of the cubes. The PPE polymer is an exceptionally fluorescent conjugated polymer that often serves as a building block for polymer-based sensing applications. By monitoring the absorption and emission of the PPE polymer, a better understanding of plasmonic effects on this polymer system was obtained. Compression of the monolayer of AgNCs on the surface of a Langmuir-Blodgett trough can be used for control of interparticle distance and, thus, the plasmon field intensity felt by an adsorbed layer of PPE polymer. In the Chapter 4, PPE (n = 15) emission was monitored as a function of the AgNC plasmonic field. A two-photon process was found to explain the unusual increase then decrease of the fluorescence intensity. This observation was attributed to exciton-exciton annihilation processes within the polymer. The annihilation process is initiated by large enhancements of the polymer absorption rate when plasmonic fields are at their highest (when the AgNCs are compressed to short interparticle distances). In chapter 5, the optical properties of PPE polymers as a function of their chain length and the AgNC density were examined. A simple study was conducted to consider the conformational/geometrical effects on PPE that were caused by the deposition of PPE onto the AgNC topography. In this study, the structure of the absorption and emission profiles were evaluated and used as evidence of polymer interchain interactions, planarization, and even the potential generation of oligomeric species through breaking of conjugation. Fundamental interactions between materials must be evaluated and optimized prior to their use in devices. This thesis serves to shed a little bit of light on the interaction of a well-defined plasmonic particle with a conjugated polymer. The Langmuir-Blodgett technique serves as a critical tool in applying these colloidally produced nanoparticles to 2D arrays in practical applications. The observation of exciton-exciton annihilation at low-energy excitation is an entirely new phenomenon that was initiated by the plasmonic properties of metal nanoparticles. It is the hope of the author that the results contained herein can aide in the use of plasmonic nanoparticles in future devices.

Moderne Methoden der Oberflächenbehandlung können Oberflächen mit besonderen Eigenschaften versehen. Diese Eigenschaften werden zunehmend durch ultradünne Schichten mit Schichtdicken von einigen Nanometern erzeugt, da mit minimalem Materialaufwand definierte Resultate erreichbar sind. Die meisten Metalle überziehen sich mit einer Oxidschicht, deren Eigenschaften von den herrschenden Umgebungsbedingungen bestimmt werden. Diese Oxidschicht bildet die Oberfläche des Festkörpers, und weist andere Eigenschaften auf als der Festkörper selbst. Darüber hinaus beeinflussen die Rauhigkeit sowie eventuell vorliegende Legierungsbestandteile die Oberflächenbeschaffenheit. Besonders geeignet zum Erzeugen ultradünner oder monomolekularer Schichten ist der Prozess der Selbstorganisation, bei dem man sich zu Nutze macht, dass oberflächenaktive Moleküle mit sich selbst und einem Substrat in Wechselwirkung treten können. Zum Verständnis der ablaufenden Vorgänge ist die Kenntnis der Prozesskinetik sowie die Charakterisierung der Substratoberfläche vor und nach der Adsorption erforderlich. Die Größenverhältnisse zwischen den adsorbierten Molekülen und der Rauheit der Oberfläche erschweren die Charakterisierung der vorliegenden Ordnung und Orientierung der erzeugten dünnen Schichten. In dieser Arbeit sind Untersuchung des Schichtbildungsverhaltens und die Charakterisierung der erzeugten Schichten aus Phosphon- und Phosphorsäurederivaten in Abhängigkeit verschiedener Eigenschaften der Substratoberflächen vorgenommen worden. Dabei kamen oberflächensensitive Methoden wie AFM, REM, SPR und XPS zum Einsatz. Es konnte gezeigt werden, dass sich die untersuchten Moleküle wie erwartet auf den Oberflächen orientieren und dabei einen Bedeckungsgrad von etwa 60% erreichen. Der Einfluss von unterschiedlichen Vorbehandlungsmethoden konnte ebenso charakterisiert werden.

Dans la gamme de tailles nanométriques, les propriétés optiques de particules uniques d'or et d'argent sont celles du solide massif modifiées par le confinement diélectrique : en particulier les Résonances de Plasmon de Surface. L'interaction lumièrenanoparticule étant très faible, l'étude d'une particule unique a pu être réalisée grâce au développement d'une technique optique originale en champ lointain basée sur la modulation spatiale de l'échantillon. Cette technique a permis la détection et la caractérisation optique géométrique de nanoparticules uniques d'environ 10 nm de diamètre, à l'aide de sources laser ou d'un continuum. L'utilisation d'une lampe blanche et d'un montage proche UltraViolet – visible – proche InfraRouge a permis l'étude de plus grosses particules et donc du mode quadrupolaire du plasmon ainsi que l'analyse de valeurs publiées des fonctions diélectriques des métaux nobles. L'étude de particules en fonction de leur taille a permis de vérifier le passage au mode quasi-statique d'oscillation collective des électrons de conduction. La corrélation des mesures optiques à la microscopie électronique à transmission a montré l'influence de la forme et des interactions entre particules sur cette réponse optique.

Les nanostructures métalliques présentent, grâce aux résonances de surface qu'elles supportent, la possibilité de confiner et de contrôler la lumière sur des dimensions très inférieures à la longueur d'onde. Durant cette thèse, nous avons étudié le cas des réseaux de fentes métalliques.<br /><br />Nous avons mis en oeuvre un calcul original des courbes de dispersion complexes des réseaux métalliques, basé sur une méthode modale et un formalisme de matrice S. Le calcul des structures de bandes photoniques complexes et de la répartition spatiale du champ électromagnétique a permis de décrire précisément les résonances de surface horizontales et verticales, leurs conditions d'excitation ainsi que leurs durées de vie radiatives et non radiatives. Leurs propriétés de confinement et de transmission de la lumière dans des fentes très fines devant la longueur d'onde offrent de nouvelles possibilités en optoélectronique.<br /><br />Nous proposons en particulier deux structures de type métal-semiconducteur-métal pour la photodétection ultrarapide, dans lesquelles le confinement de l'absorption permet de repousser le compromis habituel entre rendement et vitesse. La première structure est un réseau métal/semiconducteur dans lequel la lumière est absorbée entre les électrodes. La seconde structure permet une absorption efficace dans une fine couche sous le réseau métallique. Ces deux photodétecteurs, dont la distance inter-électrode est d'environ 100 nm, ont été fabriqués sur substrat de GaAs. Le bon accord des mesures de réflectivité et de photocourant avec la théorie a permis de valider cette approche, qui pourra notamment être appliquée aux longueurs d'onde des télécommunications.<br /><br />Les dimensions mises en jeu rendent possibles des fréquences de coupure de plusieurs centaines de GHz, avec un rendement théorique de 75 % indépendamment de la polarisation de la lumière. Ces résultats ouvrent la voie à une nouvelle génération de photodétecteurs ultrarapides.

Es werden die physikalischen Grundlagen zur inelastischen Streuung mittelschneller Elektronen im Hinblick auf die Untersuchung des Energieverlustes beschrieben. Die instrumentellen Grundlagen der Energieverlust-Spektroskopie unter besonderer Berücksichtigung des Einsatzes in Transmissionselektronenmikroskopen werden erläutert. Der Einfluß des erfaßsten Streuwinkelbereichs wird diskutiert. Es werden Möglichkeiten zur Auswertung von Energieverlustmessungen im Bereich der Interbandübergangs- und Plasmonanregungen sowie im Bereich der Anregung von tieferliegenden (Rumpf-)Zuständen angegeben. Zur Anwendung der Elektronen-Energieverlust-Spektroskopie werden einige Beispiele angeführt. Von Messungen an ionengestützt abgeschiedenen Kohlenstoff- und Kohlenstoff-Stickstoff-Schichten werden Aussagen zur elektronischen und atomaren Struktur abgeleitet. Diese Ergebnisse werden unter Berücksichtigung relevanter Strukturmodelle und Abscheideparameter diskutiert. Aus Untersuchungen von Bornitridschichten wird eine vertikale Schichtung von kubischem Bornitrid über hexagonal koordiniertem verifiziert. Die Streuphase des bei der Ionisation des Al-1s-Zustandes entstehenden Sekundärelektrons bei der Rückstreuung an den nächsten Nachbarn wird durch Untersuchung der kantenfernen Feinstruktur bestimmt. Weitere Untersuchungen kantennaher Feinstrukturen an einer amorphen SiCrAl-Schicht sowie an Kohlenstoffschichten werden vorgestellt. Mögliche Einflüsse kovalenter Bindungen auf die Ergebnisse werden dabei diskutiert. Schließlich werden räumlich hochauflösende Energieverlustmessungen vorgestellt, die zum Nachweis etwa 2 nm dicker Vanadiumoxidschichten auf Rutilkristalliten führten.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. The following patent resulted from the dissertation research: Davis, V., Simonian, A.L., Nepal, D., Balasubramanian, S, "Preparation of Precisely Controlled Thin Film Nanocomposites of Carbon Nanotubes and Biomaterials", U.S. Provisional Patent Application No. 61/000,938, filed on 30 October 2007. The following peer-reviewed publications resulted from the dissertation research: Dhriti Nepal, Shankar Balasubramanian, Aleksandr Simonian, and Virginia Davis, "Mechanically Strong Antibacterial Thin Film Based on Single-Walled Carbon Nanotubes Armored with Biopolymers", Nano Letters ASAP article, May 2008 (# equal contribution) -- Shankar Balasubramanian, Iryna B. Sorokulova, Vitaly J. Vodyanoy, and Aleksandr L. Simonian, "Lytic Phage as a Specific and Selective Probe For Detection of Staphylococcus Aureus: A Surface Plasmon Resonance Spectroscopic Study", Biosensors and Bioelectronics, 2007, 22, 948-955 -- Shankar Balasubramanian, Alexander Revzin, Aleksandr Simonian, "Electrochemical Desorption of Proteins from Gold Electrode Surface", Electroanalysis, 2006, 18, 1885-1892 (Invited article) -- Vishwaprakash Nanduri, Shankar Balasubramanian, Srinivas Sista, Vitaly J. Vodyanoy, and Aleksandr L. Simonian, "Highly Sensitive Phage-based Biosensor for the Detection of ß-galactosidase", Analytica Chimica Acta, 2007, 589, 166- 172 -- H. Luckarift, Shankar Balasubramanian, S. Paliwal, G. Johnson and A. Simonian, "Enzyme-Encapsulated Silica Monolayers For Rapid Functionalization of a Gold Surface", Colloids and Surfaces B: Biointerfaces, 2007, 58, 28-33 (Invited article) -- Dong Wei, Omar Oyarzabal, Tung-Shi Huang, Shankar Balasubramanian, Srinivas Sista, Aleksandr Simonian, "Development of Surface Plasmon Resonance Biosensor For The Identification of Campylobacter jejuni", Journal of Microbiological Methods, 2007, 69, 78-85. The following conferences presentations resulted from the dissertation research: Covalent Immobilization of Organophosphorus Hydrolase on Carbon Nanotubes for Biosensor Applications, accepted for oral presentation at 12th International Meeting on Chemical Sensors, Jul. 13-16, 2008, Columbus, OH -- Electrochemical characteristics of SWNT-biopolymer nanocomposites, accepted for 213th meeting of The Electrochemical Society, May 18-23, 2008, Phoenix, AR -- Mechanically Robust Antibacterial Thin Films Composed of Single-Walled Carbon Nanotubes and Biopolymers, 2008 AIChE Spring National Meeting, Apr. 6-10, New Orleans, LA -- Production and characterization of protein and DNA based single wall carbon nanocomposites by layer-by-layer assembly, MRS Fall Meeting, Nov. 26-30, 2007, Boston, MA -- Gold surface modified with enzyme-encapsulated silica monolayers for biosensor application, The 58th Southeast Regional Meeting of the American Chemical Society, Nov. 1-4, 2006, Augusta, GA -- Electrochemical modulation of biological interfaces, 209th meeting of The Electrochemical Society, May 7-12, 2006, Denver, CO -- SPR based biosensor using lytic phage as a specific and selective probe for staphylococcus aureus detection, 57th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Mar. 12-17, 2006, Orlando, FL -- Specific & selective detection of staphylococcus aureus by lytic phage using SPR biosensor, 57th Southeast / 61st Southwest Joint Regional Meeting of the American Chemical Society, Nov. 1-4, 2005, Memphis, TN -- Prevention of non-specific binding as a way to increase sensitivity of SPR-based sensors, 206th meeting of The Electrochemical Society, October 3-8, 2004, Honolulu, HI. Includes bibliographical references.

Gold nanoparticles are excellent candidates for all the biomedical applications due to their size and shape dependent optical and physiological properties. In this study, gold nanoparticles were synthesized chemically for bio-application. It was observed that the size and shape of gold nanoparticles depend strongly on the concentration of chemical solution, type of reducing agent used in the reaction, temperature of the solution and stabilizing agent for reaction. Transmission electron microscopy (TEM) has been used extensively to determine the size and shape of the gold nanoparticles. Optical properties of the size and shape selected nanoparticles were studied using UV-vis spectrophotometer in absorption mode. The chemically synthesized gold nanoparticles were observed to show excellent absorption property which is reflected by the presence of the characteristic surface plasmon resonance (SPR) band peak. The SPR peak was found to be predominantly dependent on the size of nanoparticles. We have observed a strong red shift with increasing the size of gold nanoparticles. The position of the SPR peak was also observed to change with shape of gold nanostructures. Synthesis and characterization of the composites of gold nanoparticles and Poly (Oanisidine) (POAS) have been carried out in this thesis. Gold-POAS materials system was characterized using UV-vis spectroscopy, TEM, Fourier Transform Infrared Spectroscopy. The chemically synthesized gold nanoparticles were successfully utilized for the study of Respiratory Syncycial Virus (RSV) interaction. Gold nanoparticles were found to inhibit the RSV infection. The electrochemical behavior of gold nanoparticles was studied and their potentials for biosensing applications were tested. Cyclic voltaammetry was performed for the detection of dopamine and ascorbic acid using gold nanoparticles of different sizes. Interaction of gold nanoparticles with Bovine Serum Albumin (BSA) has been studied via absorption spectroscopy and TEM measurements. The absorption spectra of the GNP-BSA show remarkable shift in SPR band peak towards high wavelength. Catalytic properties of the gold nanoparticles were studied by using them as a catalytic activator for the gas sensing applications.