Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 37 for “"Stokes' shift"”.
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Spectral properties of semiconductor nanocrystals and their applications
… Eabs(T), 2) the temperature dependence of the Stokes shift, and 3) the homogeneous linewidth. We relate these properties to various nanocrystal applications with particular focus on nanocrystal based microbead barcodes. We present measurements of the temperature dependence of the absorption and …
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Understanding electronic and optical properties of PbS QDs for improved photovoltaic performance
… (Chapter 2), 2) trap states (Chapter 3), and 3) Stokes shift (Chapter 4), all of which can contribute to PV performance improvements only if appropriately tailored. It is worth emphasizing that ligands which are used during QD synthesis for prevention of QD agglomeration plays a key role in …
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Borafluorenes and polyborafluorenes boron doped varients of fluorene
… (BMMP-BF) exhibits an exceptionally large Stokes shift of 16000 cm-1. To extend the conjugation and change the Stokes shift, thiophene containing derivatives BMMP-BF-T, BMMP-BF-2T, and BMMP-BF-3T were synthesized. These thiophene containing compounds exhibited anomalous two wavelength …
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Exciton Dynamics in Perovskite CsPbBr₃ Semiconductor Nanocrystals
… bands. We observe a temperature-dependent Stokes shift; while the trend is similar to the Stokes shift observed in both MAPbBr₃ and CsPbBr₃ single crystals, it does not approach zero at cryogenic temperatures, pointing to an additional contribution intrinsically present in the NCs. …
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Band edge spectroscopy of CdSe quantum dots
… and exhibits a characteristic, size dependent, Stokes shift. As a consequence, many past studies have implicated the surface as the origin of the emission. In this respect, the surface localization of photogenerated carriers qualitatively explains both the long lifetimes and redshift of the …
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Theoretical and experimental studies of optically pumped molecular gas lasers
… the possibility of CW lasing with small Stokes shift in both acetylene and HCN.
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Optical properties and biological applications of fluorescent gold nanoclusters
… water-solubility, high photostability, large Stokes shift, ultrasmall size, nontoxicity, and good biocompatibility. Despite promising applications and intensive interests, the study of the fluorescence mechanism of AuNCs has so far been limited. In order to investigate the factors that …
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4Pi-konfokale Fluoreszenzmikroskopie mit 1-Photonen-Anregung
… nutzt, bei gleichzeitiger Optimierung von Stokes-Shift, Loch- blendengröße und Objektiv-Öffnungswinkel die OTF lückenlos abgedeckt werden kann. Ebenso werden Pupillenfilter untersucht und angegeben, die zur Glättung der OTF führen. Die artefaktfreien Bilder biologischer Strukturen, die mit …
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Exciton Dynamics and Anisotropy in 2D Metal Organochalcogenolate Semiconductors
… narrow photoluminescence (PL) with a minimal Stokes shift, while AgTePh exhibits broad PL with a large Stokes shift. Using time-resolved and temperature dependent optical spectroscopy, combined with sub-gap photoexcitation studies, we demonstrate that the exciton dynamics in AgSePh films are …
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Nanomaterials from Nanocomponents: Synthesis and Properties of Hybrid Nanomaterials
… stable against sonication. The photoluminescence Stokes shift in the bound nanoparticles is shown to be reduced relative to that of unbound nanoparticles. This difference is attributed to Forster resonance energy transfer from the nanoparticles to the nanotube, leading to hot luminescence in the …
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A thermally stabilized fluorescent organic chromophore
… and the native dye, designated by a shift in one of the peaks at 1730 cm<sup>-1</sup>. The nanoparticle-dye material has been characterized through a variety of techniques, including differential scanning calorimetry, thermal gravimetric analysis, scanning electron microscopy, and …
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Applications of emerging optoelectronic materials : lead sulphide quantum dots and steam cracker tar
… our understanding of the anomalously large Stokes shift in PbS QDs; the development of a novel processing method to produce optoelectronic films from SCT and the demonstration of first applications; an in depth study of SCT as a material for windscreen de-icing, including a demonstration …
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Electronic Energy Transfer in Conjugated Organic Dendrimers and Polymers
… vibrational lineshape, and the intramolecular Stokes shift, we can obtain semi-quantitative agreement with the experimental results. To directly measure the time-dependent diffusion rate of singlet excitons in MEH-PPH, we utilize a novel femtosecond pump-dump-probe anisotropy experiment. This …
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Synthesis and characterization of new light emitting probes for sensitive detection of bio-molecules and live cells
… This property in combination with large Stokes shift contributes to extreme sensitivity of detection (ca. 10^{-13}-10^{-14} M), which makes lanthanide-based probes suitable for large variety of challenging tasks ( e.g., intracellular detection of single DNA/RNA, or protein molecules, …
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Ultra thin micro solar cells with concentration optics: fabrication, modeling and characterization
… that to achieve higher optical flux gain a large Stokes shift is required, agreeing with the previously developed theory according to thermodynamics. As called for by theory, modeling and shown from organic dye doped LSC, a semiconductor nanocrystal doped LSC was demonstrated. The careful design …
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Molecular Solvation in Phosphonium Ionic Liquids
… C153 steady-state data shows a systematic blue shift as PIL-Cl is added to solution. The system is at net higher energy at high mol fraction PIL-Cl implying that C153/PIL-Cl interactions are less favorable compared to C153/MeOH. The solute emission intensity is quenched most effectively at a mol …
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Optoelectronic properties and energy transport processes in cylindrical J-aggregates
… properties are further explored, as the Stokes shift, quantum yield, and spectral line broadening are measured as a function of temperature from 77 – 298 K. The temperature-dependent emission ratios of the C8S3 J-aggregate two-band fluorescence spectra reveal that nanotube emission is …
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The Synthesis and Evaluation of Non-Targeted Near-Infrared Heptamethine Molecular Probes
… wavelengths, fluorescence quantum yields and Stokes shifts. It is noted that most dyes synthesised within this thesis, show comparable Stokes shift but increased fluorescence quantum yields when compared against ICG and IR-820. All dyes absorb and emit within the NIR region based on excitation …
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Optical properties of size selected nanocrystallites in porous silicon
… activation. The fluorescence exhibits a large Stokes shift due to the expansion of the dimers. The emission bandwidth (even for a single crystallite) is found to be quite wide especially for the ultra small crystallites where it encompasses nearly all of the visible spectrum and the near …
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Capture and control of excitations
… because of the introduction of an artificial Stokes' shift. In addition, in this thesis I model the photophysical properties of the C8S3 J-aggregate to understand two of its properties: the long exciton migration it exhibits, and its ability to be irreversibly photobrightened and reversibly …
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