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 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 Development of Far Red written by Zheng Zheng and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of fluorophores with efficient two-photon absorption (TPA) and emission properties in the far red/NIR is important, especially for in depth in-vivo optical imaging as this wavelength range corresponds to the optical transparency window of tissues. This thesis investigates the potential of new red emitting fluorophores containing a fluorene ring for in-vivo two-photon microscopy focusing on vascular imaging on one hand and on oxygen pressure measurement on the other hand.A new series of asymmetrical fluorene-based chromophores were designed and synthesized. Their structure-property relationships were systematically investigated. It was found that most of chromophores exhibit aggregation-induced emission behaviors in the NIR region. In addition, a micelle/silica coprotection strategy was proposed to prepare nanoparticles with a less polar interior, which can be used to conserve optical properties of dipole chromophores in aqueous solution. The two-photon excited fluorescence (TPEF) measurements indicate that they all display obvious TPA activities in organic solvent and aqueous suspension. Both the NIR-emissive aggregates and nanoparticles have been successfully used for TPEF imaging of blood vessels inside mouse ear skin. The silica nanoparticles show outstanding staining of the vascular system making them perfect blood pool markers.On a second part, four new fluorene-based two-photon absorbing chromophores have been synthesized and their one- and two-photon photophysical properties were investigated. The optimum chromophore was successfully attached covalently to an oxygen responsive phosphorescent Pd-porphyrin complex by click chemistry. Two new compounds contain four or eight TPA chromophores donor connected to the phosphorescent core. The result demonstrate that the incorporation of a suitable TPA chromophore can effectively enhance the TPA of the system, allowing efficient sensitivity towards oxygen.

Download or read book Nonlinear Optical Transmission and Multiphoton Processes in Organics written by and published by . This book was released on 2005 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Evaluation of New Reactive Two photon Absorbing Dyes for Two photon Excited Fluorescence Imaging Applications written by Katherine J. Schafer and published by . This book was released on 2005 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent, cooperative advances in chemistry, biology, computing, photophysics, optics, and microelectronics have resulted in extraordinary developments in the biological sciences, resulting in the emergence of a novel area termed ‘biophotonics’. The integrative and interdisciplinary nature of biophotonics cuts across virtually all disciplines, extending the frontiers of basic cellular, molecular, and biology research through the clinical and pharmaceutical industries. This holds true for the development and application of the novel imaging modality utilizing multiphoton absorption and its extraordinary contribution to recent advances in bioimaging. Intimately involved in the revolution of nonlinear bioimaging has been the development of optical probes for probing biological function and activity.

Download or read book Photoluminescence Studies and Read Write Process of a Strong Two Photon Absorbing Chromophore written by and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optical properties of a fluorene-based chromophore exhibiting a high two-photon absorption cross section have been investigated both in the pure state and as a guest host system in poly (N-vinylcarbazole). Upon irradiation with a helium cadmium (He Cd) laser at 325 nm, the guest host sample exhibits a blueshift with a maximum emission at 459 nm. Information written onto the samples in the blue can also be read using an Ar(+) laser. The chromophore undergoes a chemical change upon irradiation in air, and has been found to no longer exhibit upconversion after this transformation. Infrared analysis of the sample (the chromophore) before and after irradiation was carried out, and the spectra suggest the formation of a new conjugated species. Other applications we have developed using this phenomenon include the successful writing of optical device structures in polymer films where the AF-50 is a guest material.

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 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 Design Synthesis and Application of Novel Conjugated Materials written by Haichang Zhang and published by Frontiers Media SA. This book was released on 2021-02-11 with total page 126 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 Photophysics of Transition Metal Complexes and Two photon Absorbing Chromophores written by 林昭辰 and published by . This book was released on 2010 with total page 97 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 Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 902 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Methods in Cellular Imaging written by Ammasi Periasamy and published by Springer. This book was released on 2013-05-27 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in technology have revolutionized the development of light microscopy techniques in biomedical research, thus improving visualization of the microstructure of cells and tissues under physiological conditions. Fluorescence microscopy methods are non-contact and non-invasive and provide high spatial and temporal resolution that other laboratory techniques cannot. This well-illustrated book targets graduate students and scientists who are new to the state-of-the-art fluorescence microscopy techniques used in biological and clinical imaging. It explains basic concepts and imaging procedures for wide-field, confocal, multiphoton excitation, fluorescence resonance energy transfer (FRET), lifetime imaging (FLIM), spectral imaging, fluorescence recovery after photobleaching (FRAP), optical tweezers, total internal reflection, high spatial resolution atomic force microscopy (AFM), and bioluminescence imaging for gene expression. The usage of these techniques in various biological applications, including calcium, pH, membrane potential, mitochondrial signaling, protein-protein interactions under various physiological conditions, and deep tissue imaging, is clearly presented. The authors describe the approaches to selecting epifluorescence microscopy, the detectors, and the image acquisition and processing software for different biological applications. Step-by-step directions on preparing different digital formats for light microscopy images on websites are also provided.

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 Biophysical Techniques in Drug Discovery written by Angeles Canales and published by Royal Society of Chemistry. This book was released on 2017-11-14 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biophysical techniques are used in many key stages of the drug discovery process including in screening for new receptor ligands, in characterising drug mechanisms, and in validating data from biochemical and cellular assays. This book provides an overview of the biophysical methods applied in drug discovery today, including traditional techniques and newer developments. Perspectives from academia and industry across a spectrum of techniques are brought together in a single volume. Small and biotherapeutic approaches are covered and strengths and limitations of each technique are presented. Case studies illustrate the application of each technique in real applied examples. Finally, the book covers recent developments in areas such as electron microscopy with discussions of their possible impact on future drug discovery. This is a go-to volume for biophysicists, analytical chemists and medicinal chemists providing a broad overview of techniques of contemporary interest in drug discovery.