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 40 for “"intersystem crossing"”.
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Spectroscopic signatures of doorway-mediated intersystem crossing
Intersystem crossing in acetylene, C₂H₂, is described by a doorway-mediated model, where singlet-triplet mixing between the first excited singlet~ state, S₁, and the manifold of low-lying T₁,₂ states is controlled by special vibrational levels of the third excited triplet state, T₃. However, the …
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Intersystem crossing in acetylene : a mechanistic study
… triplet electronic states of acetylene and the intersystem crossing process that populates these states were studied using a second-generation, supersonic jet molecular beam machine with a multispectral capability. Surface Electron Ejection (SEELEM), Ultraviolet Laser Induced Fluorescence …
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Ultrafast electron transfer and intersystem crossing in bimetallic molecules
… freedom play an important role in driving ET and intersystem crossing (ISC) on the ultrafast timescale. In this thesis, ultrafast optical and X-ray techniques are used to characterize the ET and ISC dynamics of a prototypical bimetallic FeIICoIII molecule following metal-to-metal charge transfer …
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Spectroscopic investigations of intersystem crossing and triplet state structure in acetylene
… of singlet-triplet interactions relevant to intersystem crossing in the region of the 3v3 vibrational level of the A 1A, excited electronic state of acetylene. Intersystem crossing proceeds through a "doorway" state which has been plausibly assigned as a specific low-lying vibrational level …
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Triplet Exciton Management in Organic Electronic Devices
… has been used to investigate the mechanism of intersystem crossing between singlets and triplets in the important organic light-emitting diode material, 4CzIPN. It is demonstrated that the spin-vibronic model of intersystem crossing breaks down in device-relevant solid films. Evidence is …
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Picosecond studies of free radical reactions in solution
… heavy atom effect in this reaction suggests that intersystem crossing is not involved in the rate-determining step, and that diaryl carbenes react with methanol via their singlet states.
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Thermally Activated Delayed Fluorescence Emitters: Molecular Design, Photophysics, and Sensing Application
… photophysical principles governing fluorescence, intersystem crossing, reverse intersystem crossing, and TADF, molecular design strategies aimed at controlling charge-transfer (CT) character and the singlet–triplet energy splitting (ΔEST) are discussed. A family of carbazole-coumarin derivatives …
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Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors
… the amorphous phase. We also discover that the intersystem crossing rate and emission kinetics are unaffected by the extent of torsional distortion. Finally, we apply electrostatic interactions to the other two coinage metal-bridged CMAs to explore the effect of heavy metal atoms on the …
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Reactions of Excited State Cationic Dyes
… is described in chapter 2. In the third chapter, intersystem crossing in a cyanine dye, induced by heavy atom counterions and heavy atom containing solvent is discussed. The first description and transient spectroscopy of an intra-ion pair heavy atom effect is given there. The electron transfer …
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Experimental investigation of the dynamics of S1 benzene and the development of a new UV femtosecond pulse shaper
… of the channel 3 region which is attributed to intersystem crossing. Our experimental findings contribute to theoretical observations of a higher than previously expected spin orbit coupling in organic polyatomic molecules. The concluding mechanism is mediated by a doorway state and is supported …
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Quantum chemistry for spectroscopy : a tale of three spins (S = 0, 1/2, and 1)
… states and their relevance to doorway-mediated intersystem crossing for acetylene is considered. A new diabatic characterization of the third triplet electronic state, T3, enables a vibrational analysis of data obtained from current and past experiments. The last part of this thesis reviews the …
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Delayed fluorescence as a probe of radiationless transitions in anthracene and algae
… the temperature dependence of monomolecular intersystem crossing. The associated rate constant k is found to obey an equation of the form [equation] where E = 900 ± 100 cm and k2/k1 = 800 + 200. A calculation of the relevant Franck-Condon factors using the method developed by Siebrand yields …
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Simulating and controlling non-adiabatic effects in ultrafast photochemistry
… orbit coupling to the Hamiltonian. Ultrafast intersystem crossing is observe between S\(_1\) and T\(_2\), which are degenerate along the important prefulvene reaction coordinate. These results challenge the accepted view that ultrafast intersystem crossing cannot occur in hydrocarbons due to …
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Molekulinių spinduolių optimizacija naujos kartos organiniams šviestukams /
… of triplet excitons are used for the reversible intersystem crossing, leading to 100% of internal quantum efficiency. Efficiency of those TADF OLEDs is the same as of phosphorescent ones, however with much higher lifetime. Despite this, the molecular structure of TADF emitters is quite complex …
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Optimization of molecular emitters for new generation OLEDs /
… of triplet excitons are used for the reversible intersystem crossing, leading to 100% of internal quantum efficiency. Efficiency of those TADF OLEDs is the same as of phosphorescent ones, however with much higher lifetime. Despite this, the molecular structure of TADF emitters is quite complex …
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Characterizing triplet azo biradical and corannulene- halogen complexes by laser flash photolysis
… azides, and the singlet nitrene could decay by intersystem-crossing to form triplet nitrene or by direct ring expansion reaction to produce azepine. In solution the singlet aryl nitrene underwent ring expansion reaction at room temperature, while the intersystem-cross competed with the ring …
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The Development of 2,3-Diarylindenes as Integrated Fluorescent Estrogens
… and competition from fluorescence and intersystem crossing. Crystallography indicated more planar topography for the indenes and indenones as compared to other triarylethylenes. The estrogen receptor binding affinities of the indenes, indenones, and other triarylethylenes were related …
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Interplay of Spin and Photophysics in Luminescent Open-Shell Molecular Semiconductors
… even at 295 K, with optical read-out enabled by intersystem crossing to the energetically accessible radical state. In Chapter 7, we extend these results to a luminescent biradical structure which supports a quintet (*S*=2) excited state. The light-induced cycling through this state drastically …
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Visible Emitters in Hexagonal Boron Nitride as an Optically Addressable Spin Qubit Platform
… optical dynamics and strongly spin-selective intersystem crossing dynamics, this low symmetry enables the ODMR contrast to persist under high magnetic field of arbitrary orientation, with ~μT/Hz^(1/2) magnetic-field sensitivity for bias magnetic field exceeding 50 mT, demonstrating the …
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Electronic processes in organic optoelectronics : insights gained through modeling and magnetic field effects
… from non-emissive triplet states via reverse intersystem crossing (RISC) to the bright singlet state. We use MFEs to prove a rather surprising finding that in TADF materials composed of donor-acceptor bends, the electron-hole distance fluctuates as a function of time, resulting in spontaneous …
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