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Showing 1 to 20 of 192 for “"Quantum yield"”.
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Upconversion quantum yield and luminescence of beta-NaYF4:Yb3+,Er3+ nanoparticles
… determination of the key parameter upconversion quantum yield &Phi UC with minimum uncertainty (QYUC := ratio of emitted high-energy photons to absorbed low-energy photons). The main features of the developed ISS setup present the wide tunability of P of over four orders of magnitude and a high …
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Controlling structure and composition in double-heterojunction nanorods for high quantum yield and tunable color
… reported thus far are low photoluminescence quantum yield, low color purity owing to wide size distribution, and emission over a narrow range of energies in the visible spectrum. Here we report alterations to the synthetic route which result in a narrow size and morphological distribution of …
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A novel approach to investigating chlorophyll-a fluorescence quantum yield variability in the Southern Ocean
The apparent fluorescence quantum yield of chlorophyll-a (ΦF ), i.e. the ratio of photons emitted as chlorophyll-a fluorescence to those absorbed by phytoplankton, serves as a first order measure of photosynthetic efficiency and a photophysiological indicator of the resident phytoplankton …
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Measuring and Comparing Quantum Yield in Two Species of Marine Diatoms Subjected to Constant and Fluctuating Light Conditions
… remained the same for each paired experiment. Quantum yield was measured using two methods: 14C fixation at the end of the light period to determine maximum quantum yield (Φmax), and increase in depth-integrated particulate organic carbon during the day to determine daily averaged quantum yield …
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Synthesis, Functionalization, and Characterization of Dominant UV Emitting Upconverting Nanocrystals and Absolute Quantum Yield and Power Dependence Metrics for the Elucidation of Upconversion Mechanisms
… nm) excitation. Continuing optimizations have yielded a high ytterbium (Yb) sensitizer, cubic α-NaYbF4 UCNC composition, codoped with a thulium activator, to generate excited state saturated UV transitions, 1I6 → 3F4 (349 nm) and 1D2 → 3H6 (362 nm), and their refinement to afford dominant UV …
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Method For Determination Of Singlet Oxygen Quantum Yields For New Fluorene-based Photosensitizers In Aqueous Media For The Advancement Of Photodynamic Therapy
… tissue. The measurement of the singlet oxygen quantum yield is an important determinant used to evaluate the efficiency of new photodynamic therapy agents developed in the laboratory, to screen potential photosensitizers in aqueous media.The singlet oxygen quantum yield is a quantitative …
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Tunable emission from two-dimensional semiconductor with platelet optical antennas
… thin slab leads to low absorbance (- 3%) and quantum yield (~ 10-3). Although the quantum yield of monolayer MoS2 is higher compared with its few-layer counterparts, it is still significantly lower than that would be expected for a direct-gap semiconductor. Here, we explore the possibility of …
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Ultrafast Vibrational Dynamics of Water and Confined Water in Reverse Micelles
… and Stokes Raman measurements. The exact quantum yield of the symmetric sulfonate stretch nSO-3 of AOT head group is measured using controlled mid-IR excitations and spectral measurements. The sulfonate quantum yield, ranging between 0.025 and 0.002, mainly depends on the size of reverse …
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Quantum Yields And Mechanism In Titanium Dioxide Mediated Photocatalysis
… to be 0.28 {dollar}pm{dollar} 0.03.;A method for quantum yield determinations in heterogeneous systems was developed, based on the measurements of {dollar}cdot{dollar}OH radical generation rates and the flux of absorbed photons by TiO{dollar}sb2{dollar} suspensions. In this procedure a modified …
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On the origin of photons : understanding excitons and multiexcitons in colloidal semiconductor nanocrystals
… dynamics, and (generally) low biexciton quantum yield. In a separate set of experiments, we study the temperature-dependent exciton emission dynamics of InAs quantum dots and nd that their emission is well-described by existing excitonic ne-structure models. CdSe is the classical …
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SYNTHESIS AND CHARACTERIZATION OF HIGHLY FLUORESCENT TUNABLE AZABORINE PHOTO-INDUCED ELECTRON TRANSFER GLUCOSE SENSOR
… absorption coefficient and higher fluorescent quantum yield compared to the current literature: anthracene (0.27 quantum yield in ethanol). The azaborine emission wavelength is capable of being tuned near-infrared (NIR) by controlling the power of the electron donor- and acceptor- substituents …
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Photophysics of Organic Probes and their Applications in Bioimaging & Photodynamic Therapy
… large extinction coefficients, high fluorescence quantum yields, good photostability, and reasonable two-photon absorption cross sections. Two promising compounds were further evaluated as NIR fluorescent probes in one-photon and two-photon fluorescence imaging. Chapter 3 provides the design, …
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Design, synthesis and characterization of photocage molecules for light-activated release: Applications in polymer chemistry and phototherapeutics
… Both the photocages showed excellent chemical yields and good quantum yield of photorelease. But the releasing efficiency of the photocages with an array of leaving groups were also found to be dependent on the nature of the leaving group, any of the linker used and the photocages. The plot of …
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Effect of Ozone on CO2 Assimilation and PSII Function in Plants with Contrasting Pollutant Sensitivities
… reductions in photosynthesis, growth, and yield. Plant response to ozone may vary with species, varieties, and physiological age. Comparison between sensitive and tolerant cultivars has a key role in assessing ozone damage, investigating the sites of cellular injury, and identifying ozone …
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Comparative laboratory study of photoacclimation in selected dinoflagellate and diatom species of the Benguela ecosystem
… photosynthetic capacity, pigment ratios, maximum quantum yield and chlorophyll to carbon ratio. These species were grown at irradiances of 33 (LL), 178 (ML) and 647 μmol quanta . m-2 . s-1 (HL) at a 12:12h day: night length at 17 ºC. The photosynthetic parameters, pigment concentration and Chl …
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Colloidal CdSe quantum nanowires: Synthesis, photo-induced photoluminescence enhancement and fabrication of core/shell, water-dispersible structures
… is applied to the growth of colloidal CdSe quantum wires. The synthetic conditions are optimized to control the morphology and optical properties of the quantum wires. The effects of the impurities of solvent TOPO during the synthesis were also explored. Photo-induced photoluminescence …
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Photochemistry and Photophysics of Octahedral Ruthenium Complexes
… has a higher quantum yield of ligand substitution and a lower energy metal to ligand charge transfer (MLCT) transition showing binding to DNA when irradiated at 650 nm, within the ideal PDT window of 600-850 nm.The low temperature emission and photolysis of …
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Naujų pirimidino - fenoksazino TADF spinduolių sintezė ir tyrimas /
… way to achieve 100% internal fluorescence quantum yield without involving any expensive heavy atoms by converting all excitations to singlet ones by thermal activation. Usually, this is achieved by constructing TADF molecules with electron-donating and –accepting fragments, decreasing the …
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The maximum quantum efficiency of CO2 assimilation declines with depth in the canopies of the C4 crops Miscanthus x giganteus and Zea mays
… aging leaves of M. x giganteus. The maximum quantum yield of CO2 assimilation (ΦCO2, max) was derived from the initial linear slope of the responses of leaf CO2 uptake (A) to photon flux (Q) corrected for leaf fractional light absorptance (α) measured in an integrating sphere. In addition, …
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