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 Ultrafast Dynamics and Two photon Absorption Properties of Chromophores at Interfaces written by Semere G. Bairu and published by . This book was released on 2013 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials with large two photon absorption cross sections found applications in several areas such as sensor protection, 3D micro/nano fabrication, photodynamic therapy, optical data storage, multi-photon sensing, multi-photon microscopy and imaging. Several successful research strategies were developed in literature to achieve 2PA materials with enhanced cross sections. However, the obtained cross sections are far from adequate and there is a need to develop new strategies. In a parallel development, numerous research efforts were focused on studying the dynamics of interfacial charge transfer across chromophore semiconductor interfaces, especially in the context of dye sensitized solar cells. While investigating the fundamentals of ICT, it was found that these interfaces provide greater dipolar coupling and can create surface electric fields. Thus, the hypothesis of the present thesis is to use the local electric fields and interfacial interactions to enhance the 2PA cross sections of attached chromophores. This strategy of chromophores stationed at interfaces can lead to synergistic 2PA enhancement. To prove the hypothesis and design better 2PA materials, the following research work was undertaken. Firstly, ICT dynamics on three anthracene derivatives sensitized TiO2 nanoparticles was studied to understand the influence of anchoring groups and corroborate the presence of local electric fields. Secondly, investigations were continued to probe the dynamics of electron injection and transient Stark effects in a donor acceptor chromophore sensitized TiO2 nanoparticles. Thirdly, new chromophores are synthesized that can possess strong interfacial electronic coupling with the semiconductor and create local electric fields. The 2PA cross section measurements of these chromophore sensitized semiconductor nanoparticles have shown unprecedented 2PA enhancements as high as 20-fold when the chromophores are attached to the semiconductor nanoparticles. The mechanism behind the enhancement was probed with ultrafast luminescence and absorption and the results confirmed the presence of a charge transfer state. Finally, the interfacial electric field generated at the interface of charged micelle and water was used to enhance the 2PA cross sections of chromophore that was solubilized in that region. The results presented in the thesis have confirmed that local electric fields exist at the interfaces and they can be successfully utilized to design efficient 2PA materials.
Download or read book Introduction to Organic Electronic and Optoelectronic Materials and Devices written by Sam-Shajing Sun and published by CRC Press. This book was released on 2008-05-29 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting rapid growth in research and development on organic/polymeric electronic and photonic materials and devices, Introduction to Organic Electronic and Optoelectronic Materials and Devices provides comprehensive coverage of the state-of-the-art in an accessible format. The book presents fundamentals, principles, and mechanisms complem
Download or read book 3D Digital Data Storage Using Two Photon Process A Demonstration Task Novel Multifunctional Chromophores for Electro Optic and Other Photonics Applications written by and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: New opto-electronic and composite materials with enhanced photonic performance were developed and that applicators in 3D optical data-storage, 3D optical-circuitry, 3D micro-fabrications and photorefractivity were studied. Two-photo based technology was used to do photo-crosslinking at a precise volume location to produce complex 3D opticalcircuitry such a waveguide splitters and grating couplers as well as for fabricating MEMS. Another area of our activity bas been in preparation of photonic band gap materials for visible and near-IR range. Highly monodispersed silica and polystyrene spheres of varying diameter(1OO-8OOnm) were prepared and photonic crystals made from them showed photonic pseudogaps. We have successfully infiltrated the pores with a high refractive index conjugated polymer, PPV and etched out the silica spheres. The resulting inverterphotonic crystal exhibits enhanced reflectance at the band gap. Using a new approach of photosensitization with manocrystallites of inorganic semiconductors, we have prepared photorefractive composite for operation at l.31 micrometer and this approach can be extended for preparation of photorefractive materials with a tailored spectral response. Our new materials development in collaboration with Wright lab has made it possible to use two-photon approach to write information in different layers with the capacity of terabits/cm(3), which can flow be read by using a simple CW green laser. A three dimensional digital data-storage system based on two-photon process also was demonstrated. We have written layers of digital data in a dye doped polymer media (AF-240 from Air force Polymer branch doped in PMMA) using highly localized two-photon process. We have demonstrated a new data read back system using a 532nm solid state laser and were able to read the data using confocal single photon fluorescence detection.
Download or read book Applied Photochemistry written by Rachel C. Evans and published by Springer Science & Business Media. This book was released on 2014-07-08 with total page 619 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applied Photochemistry encompasses the major applications of the chemical effects resulting from light absorption by atoms and molecules in chemistry, physics, medicine and engineering, and contains contributions from specialists in these key areas. Particular emphasis is placed both on how photochemistry contributes to these disciplines and on what the current developments are. The book starts with a general description of the interaction between light and matter, which provides the general background to photochemistry for non-specialists. The following chapters develop the general synthetic and mechanistic aspects of photochemistry as applied to both organic and inorganic materials, together with types of materials which are useful as light absorbers, emitters, sensitisers, etc. for a wide variety of applications. A detailed discussion is presented on the photochemical processes occurring in the Earth’s atmosphere, including discussion of important current aspects such as ozone depletion. Two important distinct, but interconnected, applications of photochemistry are in photocatalytic treatment of wastes and in solar energy conversion. Semiconductor photochemistry plays an important role in these and is discussed with reference to both of these areas. Free radicals and reactive oxygen species are of major importance in many chemical, biological and medical applications of photochemistry, and are discussed in depth. The following chapters discuss the relevance of using light in medicine, both with various types of phototherapy and in medical diagnostics. The development of optical sensors and probes is closely related to diagnostics, but is also relevant to many other applications, and is discussed separately. Important aspects of applied photochemistry in electronics and imaging, through processes such as photolithography, are discussed and it is shown how this is allowing the increasing miniaturisation of semiconductor devices for a wide variety of electronics applications and the development of nanometer scale devices. The final two chapters provide the basic ideas necessary to set up a photochemical laboratory and to characterise excited states. This book is aimed at those in science, engineering and medicine who are interested in applying photochemistry in a broad spectrum of areas. Each chapter has the basic theories and methods for its particular applications and directs the reader to the current, important literature in the field, making Applied Photochemistry suitable for both the novice and the experienced photochemist.
Download or read book Nanophotonics Integrating Photochemistry Optics and Nano Bio Materials Studies written by Hiroshi Masuhara and published by Elsevier. This book was released on 2004-10-09 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanophotonics: Integrating Photochemistry, Optics and Nano/Bio Materials Studies.Is an interdisciplinary research text on the application of nanophotonic (physical/chemical) research and effects in devices for applications, bridging a gap between conventional pthotophysics/photochemistry and nanoscience. Nanophotonics is a new wide research field related to photochemistry, photobiology, and photophysics in nanodimension. Under the keywords of "Photo" and "Nano", advanced scientific topics, such as spectroscopic analysis of from single molecules to nanomaterials, nanofabrication by photons, detection of single bio-molecules, near field optics, and so forth, are described here. The book is written by experts in the field of photochemistry, optics, material science, bioscience, and so on for providing advanced knowledge of nanophotonics. Nanophotonics is a new research field that is not included in any conventional discipline but widely cover evolving and promising research subjects under the keywords of "Light" and "Nanoscale". Topics included in the book are concerned with photodynamics: from single molecules to nanoparticles, spectroscopy and imaging in nanodimensions, nanofabrication, synthesis, analysis and control of nano/bio systems and so on, the book is finalized by topics of toward molecular nanophotonics. This is written primarily for graduate students, researchers, and engineers.
Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 1948 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Photoinitiators for Polymer Synthesis written by Jean-Pierre Fouassier and published by John Wiley & Sons. This book was released on 2013-01-02 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photoinitiating systems for polymerization reactions are largely encountered in a variety of traditional and high-tech sectors, such as radiation curing, (laser) imaging, (micro)electronics, optics, and medicine. This book extensively covers radical and nonradical photoinitiating systems and is divided into four parts: * Basic principles in photopolymerization reactions * Radical photoinitiating systems * Nonradical photoinitiating systems * Reactivity of the photoinitiating system The four parts present the basic concepts of photopolymerization reactions, review all of the available photoinitiating systems and deliver a thorough description of the encountered mechanisms. A large amount of experimental and theoretical data has been collected herein. This book allows the reader to gain a clear understanding by providing a general discussion of the photochemistry and chemistry involved. The most recent and exciting developments, as well as the promising prospects for new applications, are outlined.
Download or read book Investigation of Selected Photochromic Compounds for Optical Data Storage written by Alexis A. Blevins and published by . This book was released on 2007 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ICONO 98 written by Viktor Nikolaevich Zadkov and published by SPIE-International Society for Optical Engineering. This book was released on 1999 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photochromic Materials written by He Tian and published by John Wiley & Sons. This book was released on 2016-06-16 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summarizing all the latest trends and recent topics in one handy volume, this book covers everything needed for a solid understanding of photochromic materials. Following a general introduction to organic photochromic materials, the authors move on to discuss not only the underlying theory but also the properties of such materials. After a selection of pplications, they look at the latest achievements in traditional solution-phase applications, including photochromic-based molecular logic operations and memory, optically modulated supramolecular system and sensors, as well as light-tunable chemical reactions. The book then describes the hotspot areas of photo-switchable surfaces and nanomaterials, photochromic-based luminescence/electronic devices and bulk materials together with light-regulated biological and bio-chemical systems. The authors conclude with a focus on current industrial applications and the future outlook for these materials. Written with both senior researchers and entrants to the field in mind.
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 Springer Handbook of Lasers and Optics written by Frank Träger and published by Springer Science & Business Media. This book was released on 2012-05-05 with total page 1704 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition features numerous updates and additions. Especially 4 new chapters on Fiber Optics, Integrated Optics, Frequency Combs and Interferometry reflect the changes since the first edition. In addition, major complete updates for the chapters: Optical Materials and Their Properties, Optical Detectors, Nanooptics, and Optics far Beyond the Diffraction Limit. Features Contains over 1000 two-color illustrations. Includes over 120 comprehensive tables with properties of optical materials and light sources. Emphasizes physical concepts over extensive mathematical derivations. Chapters with summaries, detailed index Delivers a wealth of up-to-date references.
Download or read book Optically Induced Nanostructures written by Karsten König and published by Walter de Gruyter GmbH & Co KG. This book was released on 2015-05-19 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructuring of materials is a task at the heart of many modern disciplines in mechanical engineering, as well as optics, electronics, and the life sciences. This book includes an introduction to the relevant nonlinear optical processes associated with very short laser pulses for the generation of structures far below the classical optical diffraction limit of about 200 nanometers as well as coverage of state-of-the-art technical and biomedical applications. These applications include silicon and glass wafer processing, production of nanowires, laser transfection and cell reprogramming, optical cleaning, surface treatments of implants, nanowires, 3D nanoprinting, STED lithography, friction modification, and integrated optics. The book highlights also the use of modern femtosecond laser microscopes and nanoscopes as novel nanoprocessing tools.
Download or read book Science Abstracts written by and published by . This book was released on 1993 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photon Working Switches written by Yasushi Yokoyama and published by Springer. This book was released on 2017-05-29 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on photoswitches. The objective of the book is to introduce researchers and graduate course students who are interested in "photon-working switches" not only to the fundamentals but also to the latest research being carried out in this field. Light can reach a target substrate without any physical contact to deliver energy. The energy can induce changes in the structure of the molecules included in the substrate so that its properties and functions are made switchable by light irradiation. When a substrate is able to revert to its original state, this system can be regarded as a "photon-working switch". The terms "photon-working switches" or "photoswitches" are almost equivalent in meaning to "photochromism"; however, they focus on the "switching of functions" of chemical species rather than their "reversible transformation". Most of the authors of this volume are members of PHENICS, an international research group on organic molecular photoswitches composed of research institutions from France, Japan, Russia, China and Germany. Since its inception in 2008, PHENICS has promoted active research to develop the field. This book commemorates the group's eighth year of collaborative research.
