Download or read book Synthesis of Novel Fluorene based Two photon Absorbing Molecules and Their Applications in Optical Data Storage Microfabrication and Stimulated Emission Depletion written by Ciceron Yanez and published by . This book was released on 2009 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-photon absorption (2PA) has been used for a number of scientific and technological applications, exploiting the fact that the 2PA probability is directly proportional to the square of the incident light intensity (while one-photon absorption bears a linear relation to the incident light intensity). This intrinsic property of 2PA leads to 3D spatial localization, important in fields such as optical data storage, fluorescence microscopy, and 3D microfabrication. The spatial confinement that 2PA enables has been used to induce photochemical and photophysical events in increasingly smaller volumes and allowed nonlinear, 2PA-based, technologies to reach sub-diffraction limit resolutions. The primary focus of this dissertation is the development of novel, efficient 2PA, fluorene-based molecules to be used either as photoacid generators (PAGs) or fluorophores. A second aim is to develop more effective methods of synthesizing these compounds. As a third and final objective, the new molecules were used to develop a write-once-read many (WORM) optical data storage system, and stimulated emission depletion probes for bioimaging. In Chapter I, the microwave-assisted synthesis of triarylsulfonium salt photoacid generators (PAGs) from their diphenyliodonium counterparts is reported. The microwave-assisted synthesis of these novel sulfonium salts afforded reaction times 90 to 420 times faster than conventional thermal conditions, with photoacid quantum yields of new sulfonium PAGs ranging from 0.01 to 0.4. These PAGs were used to develop a fluorescence readout-based, nonlinear three-dimensional (3D) optical data storage system (Chapter II). In this system, writing was achieved by acid generation upon two-photon absorption (2PA) of a PAG (at 710 or 730 nm). Readout was then performed by interrogating two-photon absorbing dyes, after protonation, at 860 nm. Two-photon recording and readout of voxels was demonstrated in five and eight consecutive, crosstalk-free layers within a polymer matrix, generating a data storage capacity of up to 1.8 x 1013 bits/cm3. The possibility of using these PAGs in microfabrication is described in Chapter III, where two-photon induced cationic ring-opening polymerization (CROP) crosslinking of an SU8 resin is employed to produce free-standing microstructures. Chapter IV describes the investigation of one- and two-photon stimulated emission transitions by the fluorescence quenching of a sulfonyl-containing fluorene compound in solution at room temperate using a picosecond pump-probe technique. The nature of stimulated transitions under various fluorescence excitation and quenching conditions were analyzed theoretically, and good agreement with experimental data was demonstrated. Two-photon stimulated transitions S1 [right arrow] S0 were shown at [lambda subscript q] = 1064 nm. The two-photon stimulated emission cross section of the sulfonyl fluorophore was estimated as [delta]2[subscript PE]([lambda subscript q]) [approximately] 240 - 280 GM, making this compound a good candidate for use in two-photon stimulated emission depletion (STED) microscopy.
Download or read book Enhanced Two photon Absorption in a Squaraine fluorene squaraine Dye written by William V. Moreshead and published by . This book was released on 2013 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery of any new technology is usually accompanied by a need for new or improved materials which make that technology useful in practical applications. In the case of two-photon absorption (2PA) this has truly been the case. Since its first demonstration in 1961, there has been an ever increasing quest to understand the relationships between two-photon absorption and the structure of two-photon absorbing materials. This quest has been motivated by the many applications for 2PA which have been reported, including fluorescence bioimaging, 3D microfabrication, 3D optical data storage, upconverted lasing, and photodynamic therapy. The work presented in this dissertation represents another step in the effort to better understand the structure/property relationships of 2PA. In this work a new, squaraine-fluorene-squaraine molecule, proposed through a joint effort of quantum and synthetic chemists, was synthesized and its photophysical properties were measured. The measurements included linear and two-photon photophysical properties, as well as solvatochromic behavior. Quantum calculations were done to aid in understanding those photophysical and solvatochromic properties. A single squaraine dye was also synthesized and used as a model compound to assist in understanding this new structure. In Chapter 1 an introduction to 2PA and several of its applications is given. Chapter 2 gives a background of 2PA structure/property relationships that have been reported to date, based on work done with polymethine dyes. Chapter 3 gives a full account of the synthesis, characterization, and detailed quantum chemical analyses of this new squaraine-fluorene-squaraine molecule and the corresponding model compound squaraine dye. Chapter 4 gives some additional work and suggested future directions.
Download or read book Two Photon Coherence and Ultrafast Optical Storage in Organic Molecules written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project explored structure-property relationships relevant to enhancement of two-photon absorption (2PA) in organic dendritic molecules for optical power limiting. We synthesized and studied two series of novel monodisperse dendrimers built of identical blocks of thriphenylamine-based chromophores, BDPAS and BDPADSB. With both series, we observed strong cooperative enhancement of two- and three-photon absorption. We showed that this effect is due to conjugation between constituent branches. For lower generation dendriemers, the peak 2PA cross section was found to increase faster than linearly with the number of pi-electrons. For the largest dendrimer, 4SG2, the largest absolute values of molecular 2PA- and 3PA cross section was shown, 1.1 x 10(exp-46) cm(exp 4)s s and 10(exp-79) cm(exp 6)s(exp2), respectively. We compared the 2PA cross section of the two dendrimer series, and concluded that enlarging the conjugation system between the adjacent nitrogen atoms can create remarkably large sigma value. We developed a new method for quantitative determination of the extent of conjugation by comparing one- and three-photon absorption measurements. Coherent domain structure was deduced from 3PA measurements in the BDPAS series. It was found that, in terms of largest coherence domain size, 4SG0 is the optimum dendrimer generation, which corresponds to an effective maximum number of 150 conjugated pi-electrons.
Download or read book Investigation of Two Photon Polymerization Technique for Applications in Photonics and Biomedicine written by Aleksandr Ovsianikov and published by Cuvillier Verlag. This book was released on 2009-06-04 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two photon Cross Section Enhancement of Photochromic Compounds for Use in 3D Optical Data Storage written by Gheorghe Luchita and published by . This book was released on 2011 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rewritable photochrome-based 3D optical data storage requires photochromic molecules with high two-photon absorption (2PA) cross sections. Currently, the low value of two-photon absorption cross sections of existing photochromes makes them unsuitable for practical application in 3D data storage. Worldwide attempts to increase the cross section of photochromic molecules by altering the chemical structure have yielded poor results. In this work, two ways to increase the two-photon absorption cross sections of photochromes were investigated. In the first method, partial success demonstrated by extending the conjugation of a photochromic molecule, a high two-photon absorption cross section of the closed form isomer and high photoconversion to the closed form were realized. At the same time, a decrease in photoswitching quantum yield and low photoconversion to open form was observed. A discussion is provided to explain the results, suggesting that the proposed method of extending the conjugation may not solve the problem. For this reason a new method for effective two-photon absorption cross section enhancement of photochromes was proposed. As a proof of principle, a new two-photon absorbing dye with a hydrogen bonding moiety was synthesized and used for the formation of supramolecular structures with a photochromic compound. Theoretical reasoning and experimental demonstration of energy transfer from the dye to the photochrome under one and two-photon excitation confirmed the practical value of the method. The effects of a 2PA dye on the photochromic properties of a diarylethene were investigated using a model compound to simplify data analysis. Formation of supramolecular structures was revealed using 1H NMR spectroscopic methods. The model compound, having the same hydrogen bonding moiety as 2PA dye, has been demonstrated to bind with photochrome molecules at very low concentrations. Photochromic properties of 2,3-bis(2,4,5-trimethyl-3-thienyl)maleimide, including conversions at the photostationary state, extinction coefficients, photoisomerization reaction rates and quantum yields, were shown to be affected by hydrogen bonding with the model compound - 2,6-bis-(acetamido)pyridine. The extent of this change was determined and discussed, demonstrating a balanced supramolecular strategy to modulate photochemical and photophysical properties of this important class of photochromic material.
Download or read book Design Synthesis and Spectral Property Studies of Novel Two photon Absorbing Chromophores written by Tzu-Chau Lin and published by . This book was released on 2002 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Processing of Novel Chromophores for Electro Optic Applications written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our program involves development and applications of second-order optical materials which are also multifunctional, i.e., they exhibit more than one functionality and in some cases, new properties derived from a combination of more than one functionality . We specifically focused on applications in electro-optic modulation and photorefracitivity. Our effort has focused on developing electro-optic chromophores which offer extended transparency in the visible (to 633 nm), large r-coefficient, as well as high thermal and temporal stability of electrically poled alignment. Earlier we have developed an electro-optic chromophore, APSS, which was processed using an isocyanate containing liquid polymer to produce a thermally stable electrically poled polyurethane based electro-optic polymer. In order to further improve on optical losses in the visible range (633nm), enhance thermal stability and achieve a better control of the poling process, we have made chemical modifications and synthesized a related chromophore APSAS. This chromophore containing linkable four hydroxy sites, permits the usage of a smaller isocyanate, tolulene diisocyanate, with broader optical transparency, to produce rigid cross-linked polyurethane structures. In addition, we tested waveguide parameters of these chromophores. A waveguide modulator was fabricated using APSS to study processing optimization of this modulator. APSS and APSAS also exhibit multifunctionality: A strong two-photon absorption, photobleaching and up-converted emission. APSS exhibits photobleaching when illuminated with high peak power femtosecond pulse lasers. Utilizing this photobleaching 3D optical data storage was illustrated with a Buggs Bunny cartoon video in which each movie frame was stored in layers 5 microns apart. The two-photon exited photosensitization using APSS was also use for a new approach of two-photon photo.
Download or read book Development of Novel Two Photon Absorbing Chromophores written by and published by . This book was released on 2006 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been much interest in the development of two-photon absorbing materials and many efforts to understand the nonlinear absorption properties of these dyes, but this area is still not well understood. A computational model has been developed in our lab to understand the nanosecond nonlinear absorption properties that incorporate all of the measured one-photon photophysical parameters of a class of materials called AFX. We have investigated the nonlinear and the photophysical properties of the AFX chromophores including the two-photon absorption cross-section, the excited state cross-section, the intersystem crossing quantum yield, and the singlet and triplet excited state lifetimes using a variety of experimental techniques that include UV-visible, fluorescence and phosphorescence spectroscopy, time correlated single photon counting, ultrafast transient absorption, and nanosecond laser flash photolysis. The model accurately predicts the nanosecond nonlinear transmittance data using experimentally measured parameters.
Download or read book Proceedings of the First International Workshop on Optical Power Limiting written by Francois Kajzar and published by CRC Press. This book was released on 1999 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Perovskite Photovoltaics written by Aparna Thankappan and published by Academic Press. This book was released on 2018-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskite Photovoltaics: Basic to Advanced Concepts and Implementation examines the emergence of perovskite photovoltaics, associated challenges and opportunities, and how to achieve broader development. Consolidating developments in perovskite photovoltaics, including recent progress solar cells, this text also highlights advances and the research necessary for sustaining energy. Addressing different photovoltaics fields with tailored content for what makes perovskite solar cells suitable, and including commercialization examples of large-scale perovskite solar technology. The book also contains a detailed analysis of the implementation and economic viability of perovskite solar cells, highlighting what photovoltaic devices need to be generated by low cost, non-toxic, earth abundant materials using environmentally scalable processes. This book is a valuable resource engineers, scientists and researchers, and all those who wish to broaden their knowledge on flexible perovskite solar cells. Includes contributions by leading solar cell academics, industrialists, researchers and institutions across the globe Addresses different photovoltaics fields with tailored content for what makes perovskite solar cells different Provides commercialization examples of large-scale perovskite solar technology, giving users detailed analysis on the implementation, technical challenges and economic viability of perovskite solar cells
Download or read book Organic Nanostructures for Next Generation Devices written by Katharina Al-Shamery and published by Springer Science & Business Media. This book was released on 2007-12-29 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This jaw-dropping window on the future is the first comprehensive overview of the fabrication, fundamental properties, and applications of a new class of nanoscaled organic materials. These materials offer incredible scope to scientists wanting to exploit their optical and electronic properties and offer the potential to create a new generation of tiny devices with powerful applications. Altogether, the book offers a unique integration of organic materials science basics, nanostructured organic materials fabrication, and device applications.
Download or read book Electrochemical Immunosensors and Aptasensors written by Paolo Ugo and published by MDPI. This book was released on 2018-03-23 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Electrochemical Immunosensors and Aptasensors" that was published in Chemosensors
Download or read book Physics Of Nonlinear Optics written by Guang S He and published by World Scientific Publishing Company. This book was released on 1999-12-29 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear optics has been a rapidly growing field in recent decades. It is based on the study of effects and phenomena related to the interaction of intense coherent light radiation with matter.Physics of Nonlinear Optics describes various major nonlinear optical effects, including physical principles, experimental techniques, up-to-date research achievements, and current or potential applications. This book features clear conceptual descriptions, concise formulations, and emphasizes both theoretical and experimental aspects of nonlinear optics. The readability of this book is particularly enhanced by a series of color photographs showing the spectacular appearances of various nonlinear optical effects.Both authors of this book are outstanding research scientists renowned in their professional areas. Their major research achievements in nonlinear optics include the pioneering studies of two-wave-coupled refractive-index change, Raman-enhanced self-focusing, optical-frequency Pockels effect, stimulated Kerr scattering, optical phase-conjugation via backward stimulated emission, and two-photon-absorption based optical limiting, stabilization and reshaping.
Download or read book Direct Alcohol Fuel Cells written by Horacio R. Corti and published by Springer Science & Business Media. This book was released on 2013-12-02 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct Alcohol Fuel Cells: Materials, Performance, Durability and Applications begins with an introductory overview of direct alcohol fuel cells (DAFC); it focuses on the main goals and challenges in the areas of materials development, performance, and commercialization. The preparation and the properties of the anodic catalysts used for the oxidation of methanol, higher alcohols, and alcohol tolerant cathodes are then described. The membranes used as proton conductors in DAFC are examined, as well as alkaline membranes, focusing on the electrical conductivity and alcohol permeability. The use of different kinds of carbon materials as catalyst supports, gas diffusion layers, and current collectors in DAFC is also discussed. State of the art of the modeling is used to estimate performance and durability. The closing chapter reviews the use of DAFC in portable equipment and mobile devices and features a detailed discussion on the mechanisms of component degradation which limits their durability. This book is written to facilitate the understanding of DAFC technology, applications, and future challenges. It is an excellent introduction for electrochemical and material engineers interested in small fuel cells as portable energy sources, scientists focused on materials science for energy production and storage, as well as policy-makers in the area of renewable energies.
Download or read book Laser Surface Interactions for New Materials Production written by Antonio Miotello and published by Springer Science & Business Media. This book was released on 2009-12-05 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview on nanosecond and ultra-short laser-induced phenomena and the related diagnostics. It grew from the lectures of the International School "Laser-surface interactions for new materials production" held in July 2008.
Download or read book Treatment of Micropollutants in Water and Wastewater written by Jurate Virkutyte and published by IWA Publishing. This book was released on 2010-08-14 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last few years there has been a growing concern over the increasing concentration of micropollutants originating from a great variety of sources including pharmaceutical, chemical engineering and personal care product industries in rivers, lakes, soil and groundwater. As most of the micropollutants are polar and persistent compounds, they are only partially or not at all removed from wastewater and thus can enter the environment posing a great risk to the biota. It is hypothesized that wastewater is one of the most important point sources for micropollutants. Treatment of Micropollutants in Water and Wastewater gives a comprehensive overview of modern analytical methods and will summarize novel single and hybrid methods to remove continuously emerging contaminants - micropollutants from the aqueous phase. New trends (e.g. sensor technology, nanotechnology and hybrid treatment technologies) are described in detail. The book is very timely because the new techniques are still in the development phase and have to be realized not only in the laboratory but also on a larger scale. The content of the book is divided into chapters that present current descriptive and analytical methods that are available to detect and measure micropollutants together with detailed information on various chemical, biological and physicochemical methods that have evolved over the last few decades. Treatment of Micropollutants in Water and Wastewater will also enable readers to make well informed choices through providing an understanding of why and how micropollutants must be removed from water sources, and what are the most appropriate and available techniques for providing a cost and technologically effective and sustainable solutions for reaching the goal of micropollutant-free water and wastewater. The book will be suitable for water and wastewater professionals as well for students and researchers in civil engineering, environmental engineering and process engineering fields.
Download or read book Carbon written by Tapan Gupta and published by Springer. This book was released on 2018-09-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: All living things contain carbon in some form, as it is the primary component of macromolecules including proteins, lipids, nucleic acids (RNA and DNA), and carbohydrates. As a matter of fact, it is the backbone of all organic (chemistry) compounds forming different kinds of bonds. Carbon: The Black, the Gray and the Transparent is not a complete scientific history of the material, but a book that describes key discoveries about this old faithful element while encouraging broader perspectives and approaches to its research due to its vast applications. All allotropes of carbon are described in this book, along with their properties, uses, and methods of procurement or manufacturing. Black carbon is represented by coal, gray carbon is represented by graphite, and transparent carbon is represented by diamond.
