Download or read book Design and Development of a Two Photon Absorption Induced Fluorescence Spectrometer and the Investigation of Nonlinear Optical Properties of Organic Chromophores written by Evripidis Michail and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultrafast Two photon Absorption in Organic Molecules written by Nikolay Sergeevich Makarov and published by . This book was released on 2010 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation explores quantitative two-photon absorption spectroscopy to relate molecular structure with optical properties of organic chromophores. The dissertation describes an advanced fluorescence-based technique for reliable measurements of the two-photon spectra and cross sections. To facilitate the measurements it establishes a set of reference compounds measured with a 15% absolute accuracy covering a broad range of excitation and fluorescence wavelengths. The dissertation shows that in many cases the few-essential-levels model can be successfully applied for the description and interpretation of two-photon absorption spectra and cross sections, at least for the low-energy transitions. The dissertation presents examples of applications of two-photon absorption for volumetric optical storage and cancer tumor detection. It describes the basic principles of the two-photon absorption-based optical memory and limitations imposed on two-photon sensitivity of photochromic materials by a necessity of fast access to the data. It also proposes a novel technique for sensitive detection of cancer cells by using two-photon excitation of near-IR fluorescence of a commercial dye and discusses the mechanisms responsible for differentiation between the normal and the cancer cells. The methods described in this dissertation can be applied to understanding the relations between structure and two-photon absorption strength of individual transitions of organic and biological chromophores, which can be used for design of new materials, maximally adapted for particular applications.
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 Molecular and Laser Spectroscopy written by V.P. Gupta and published by Elsevier. This book was released on 2017-09-18 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular and Laser Spectroscopy: Advances and Applications provides students and researchers with an up-to-date understanding of the fast-developing area of molecular and laser spectroscopy. Editor V.P. Gupta has brought together the eminent scientists on a selection of topics to develop a systematic approach, first covering basic principles needed to understand each cutting-edge technique and application. This book acts as a standard reference for advanced students of molecular and laser spectroscopy and as a graduate text for new entrants in the field. The book covers a wide range of applications of molecular and laser spectroscopy in diverse areas ranging from materials to medicine and defence, biomedical research, environmental monitoring, forensic investigations, food and agriculture, and chemical, pharmaceutical and petrochemical processes. Researchers and scientific personnel in these fields will learn the latest techniques in order to put them to practical use in their work. Covers several areas of spectroscopy research in a single volume, saving researchers time Includes exhaustive lists of research articles, reviews and books at the end of each chapter to point readers in the right direction for further learning Features illustrative examples of the varied applications Serves as a practical guide to those interested in using molecular and laser spectroscopy tools in their research and field applications
Download or read book Topics in Fluorescence Spectroscopy written by Joseph R. Lakowicz and published by Springer. This book was released on 2013-04-20 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorescence spectroscopy continues its advance to more sophisticated methods and applications. As one looks over the previous decades, its appears that the first practical instruments for time-resolved measurements appeared in the 1970’s. The instrumentation and analysis methods for time-resolved fluorescence advanced rapidly throughout the 1980’s. Since 1990 we have witnessed a rapid migration of the principles of time-resolved fluorescence to cell biology and clinical appli- tions. Most recently, we have seen the introduction of multi-photon excitation, pump-probe and stimulated emission methods for studies of biological mac- molecules and for cellular imaging. These advanced topics are the subject of the present volume. Two-photon excitation was first predicted by Maria Goppert-Mayer in 1931, but was not experimentally observed until 1961. Observation of two-photon excitation required the introduction of lasers which provided adequate photon density for multi-photon absorption. Since the early observations of two-photon excitation in the 1960s, multi-photon spectroscopy has been limited to somewhat exotic applications of chemical physics, where it is used to study the electronic symmetry of small molecules. Placing one’s self back in 1980, it would be hard to imagine the use of multi-photon excitation in biophysics or cellular imaging.
Download or read book Design Synthesis and Characterization of New Two photon Absorbing 2PA Fluorescent Dyes and Bioconjugates and Their Applications in Bioimaging written by Carolina D. Andrade and published by . This book was released on 2010 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of new multiphoton absorbing materials has attracted the attention of researchers for the last two decades. The advantages that multiphoton absorbing materials offer, versus their one-photon absorbing counterparts, rely on the nature of the nonlinearity of the absorption process, where two photons are absorbed simultaneously offering increased 3D resolution, deeper penetration, and less photobleaching and photodamage as a result of a more confined excitation. The applications of efficient two-photon absorbing materials have been extensively expanding into the fields of photodynamic therapy, microscopy, and optical data storage. One of the fields where an increased interest in multiphoton absorbing materials has been most evident is in bioimaging, in particular, when different cellular processes and organelles need to be studied by fluorescence microscopy. The goal of this research was to develop efficient two-photon absorption (2PA) compounds to be used in fluorescence bioimaging, meaning that such compounds need to posses good optical properties, such as high fluorescence quantum yield, 2PA cross section, and photostability. In the first chapter of this dissertation, we describe the synthesis and structural characterization of a new series of fluorescent donor-acceptor and acceptor-acceptor molecules based on the fluorenyl ring system that incorporated functionalities such as alkynes and thiophene rings, through efficient Pd-catalyzed Sonogashira and Stille coupling reactions, in order to increase the length of the conjugation in our systems. These new molecules proved to have high two-photon absorption (2PA), and the effect of these functionalities on their 2PA cross section values was evaluated. Finally, their use in two-photon fluorescence microscopy (2PFM) imaging was demonstrated. One of the limitations of the compounds described in Chapter 1 was their poor water solubility; this issue was addressed in Chapter 2. The use of micelles in drug delivery has been shown to be an area of increasing interest over the last decade. In the bioimaging field, it is key to have dye molecules with a high degree of water solubility to enable cells to uptake the dye. By enclosing a hydrophobic dye in Pluronic® F-127 micelles, we developed a system that facilitates the use of 2PA molecules (typically hydrophobic) in biological systems for nonlinear biophotonic applications, specifically to image the lysosomes. Furthermore, we report in this chapter the efficient microwave-assisted synthesis of the dye used in this study. In addition, linear photophysical and photochemical parameters, two-photon absorption (2PA), and superfluorescence properties of the dye studied in Chapter 2, were investigated in Chapter 3. The steady-state absorption, fluorescence, and excitation anisotropy spectra of this dye were measured in several organic solvents and aqueous media. In Chapter 4, we describe the preparation and the use of an efficient and novel two-photon absorbing fluorescent probe conjugated to an antibody that confers selectivity towards the vascular endothelial growth factor receptor 2 (VEGFR-2) in porcine aortic endothelial cells that express this receptor (PAE-KDR). It is known that this receptor is overexpressed in certain cancer processes. Thus, targeting of this receptor will be useful to image the tumor vasculature. It was observed that when the dye was incubated with cells that do not express the receptor, no effective binding between the bioconjugate and the cells took place, resulting in very poor, nonspecific fluorescence images by both one and two-photon excitation. On the other hand, when the dye was incubated with cells that expressed VEGFR-2, efficient imaging of the cells was obtained, even at very low concentrations (0.4[micrometer]). Moreover, incubation of the bioconjugate with tissue facilitated successful imaging of vasculature in mouse embryonic tissue.
Download or read book Nonlinear Optics written by and published by . This book was released on 2002 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conference Proceedings written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simultaneous Control of Emission Localization and Two photon Absorption Efficiency in Dissymmetrical Chromophores written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the present work is to demonstrate that combined spectral tuning of fluorescence and two-photon absorption (TPA) properties of multipolar chromophores can be achieved by introduction of slight electronic chemical dissymmetry. In that perspective, two novel series of structurally related chromophores have been designed and studied: a first series based on rod-like quadrupolar chromophores bearing different electron-donating (D) end groups and a second series based on three-branched octupolar chromophores built from a trigonal donating moiety and bearing various acceptor (A) peripheral groups. The influence of the electronic dissymmetry is investigated by combined experimental and theoretical studies of the linear and nonlinear optical properties of dissymmetric chromophores compared to their symmetrical counterparts. In both types of systems (i.e. quadrupoles and octupoles) experiments and theory reveal that excitation is essentially delocalized and that excitation involves synchronized charge redistribution between the different D and A moieties within the multipolar structure (i.e. concerted intramolecular charge transfer). In contrast, the emission stems only from a particular dipolar subunit bearing the strongest D or A moieties due to fast excitation localization after excitation prior to emission. Hence control of emission characteristics (polarization and emission spectrum) in addition to localization can be achieved by controlled introduction of electronic dissymmetry (i.e. replacement of one of the D or A end-groups by a slightly stronger D(prime) or A(prime) units). Interestingly dissymmetrical functionalization of both quadrupolar and octupolar compounds does not lead to significant loss in TPA responses and can even be beneficial due to the spectral broadening and peak position tuning that it allows. This study thus reveals an original molecular engineering route strategy allowing major TPA enhancement in multipolar structures due to concerted multidimensional ICT while providing for spatial control of emission localization. Such route could be extended to more intricate (dendritic) and multipolar systems (3D).
Download or read book Polymer Journal written by and published by . This book was released on 2008 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dual Mechanism Nonlinear Response of Selected Metal Organic Chromophores written by John D. Peak and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The goal for the research described herein is the development of a series of transition metal based metal organic chromophores that display both two-photon and excited state absorption (TPA/ESA) character. With this goal in mind, we present the preparation and photophysical characterization for a series of metal-organic chromophores containing a two photon absorbing bipyridine core combined with a transition metal component which yields a long-lived triplet excited state. The combination of these two photophysical properties represents a dual mode nonlinear optical (NLO) mechanism. Three major areas of interest for this project are addressed here. First, to develop and instrument an in-house photophysical apparatus with the ability to evaluate and measure two photon activity as well as detect nonlinear optical responses. Second, to synthesize, characterize and evaluate an all organic chromophore system, centered on a bipyridine core, which utilizes known TPA architecture. Lastly, to synthesize, characterize and evaluate the metal organic analogs of the TPA chromophore system utilizing transition metals with high spin-orbit coupling values which help create long-lived triplet excited states leading to a possible ESA. The metal-organic analogs in turn should exhibit a dual mechanism for NLO response comprised of both TPA and ESA.
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 Optics Letters written by and published by . This book was released on 2006 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Single and Two photon Fluorescence Studies of Linear and Non linear Optical Chromophores written by and published by . This book was released on 2008 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solid Solution Studies of the Molecular Nonlinear Optical Properties of Organic Chromophores written by David Healy and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
