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 “"Time Resolved Spectroscopy"”.
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Femtosecond time-resolved spectroscopy of organic molecular crystals
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1988.
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Investigations of intramolecular dynamics by picosecond time-resolved spectroscopy
… redistribution (IVR) is studied by picosecond time resolved fluorescence depletion (TRFD), a technique which directly measures the ultrafast relaxation processes of the initially prepared vibronic level. Fluorescence depletion decays and dispersed fluorescence spectra of 19 vibronic features in …
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Time Resolved Spectroscopy in InAs and InSb based Narrow-Gap Semiconductors
… dynamics in semiconductors on femtosecond timescales. Time resolved spectroscopy is an excellent tool to probe the relaxation dynamics of photoexcited carriers; where after the initial photoexcitation, the nonequilibrium population of electrons and holes relax by a series of scattering …
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Boron Particle Ignition and Combustion in a Shock Tube Using Time -Resolved Spectroscopy
… by a factor of four in ignition and burning times as the mole fraction ratio XF/XO2 is increased from 0 to 0.25. For values of XF/XO2 greater than 0.5 there is little change of ignition burning time with XF/XO2 . Spectroscopic data taken in pure oxygen environments show residual BO2 emission …
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Techniques in frequency conversion and time-resolved spectroscopy with nonlinear optical processes in the femtosecond regime
Nichtlineare Frequenzumsetzung der niederenergetischen femtosekunden Laserpulsen wurde in den Festkörpermitteln nachgeforscht. Ramanumwandlung im weiss-Licht-freien Regime des impulsiven stimulierten Raman Streuungs wurde erzielt, indem man KGW-Kristall mit den Bessel-Lichtstrahl pumpte. …
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Development of Broadband Time-Resolved Spectroscopy and Investigation of the Dynamics of Photoexcited Carriers and Lattice Excitations in Chiral Weyl Semimetals
… both technological developments of broadband time-resolved ultrafast spectroscopy and investigation of the dynamics of photoexcited carriers and topological phonons in chiral Weyl semimetals. In the first portion of this thesis, we describe a novel, optical pump supercontinuum probe technique …
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Advanced Spectroscopic Methods for Photochemical and Electrochemical Systems
… effect were revealed using Operando X-ray spectroscopy. Case of Photocatalyst: Plants are home to one of the oldest natural photocatalysts, which harvest solar energy and convert it into chemical energy through photosynthesis. The solar light harvested is efficiently transferred to the …
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Cathodoluminescence of radiation damage, non-stoichiometric and impurity defects in cadmium telluride
… of the excitation intensity dependence, time resolved spectroscopy and temperature dependence of the emissions. Sharp exciton peaks at 778.17nm (1.5930eV) and 781.5nm (1.5862ev) are attributed respectively to the annihilation of excitons bound to neutral Group III impurity donors and to …
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Detecting surface inhomogeneity of asteroids
… composition inhomogeneity on asteroids using time-series spectroscopy and photometry. Observations were conducted on three test cases—Pluto, asteroid 2005 EK70, and the weather satellite Meteosat-11 using the Mookodi instrument on the Lesedi telescope. For Pluto, time-resolved spectroscopy …
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Design, Synthesis, and Photophysical Investigation of Porphyrin-containing Polymer-wrapped Single-walled Carbon Nanotubes
… quenching of the porphyrin-based fluorescence. Time-resolved spectroscopy revealed a simultaneous rise and decay of the porphyrin radical cation and SWNT electron polaron spectroscopic signatures indicative of photoinduced electron transfer. A new polymer, S-PBN(b)-Ph2PZn3, was then synthesized …
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Electronic Energy Transfer in Conjugated Organic Dendrimers and Polymers
… dendrimers are elucidated via steady-state and time-resolved spectroscopy on specially synthesized PA dendrons, and comparison with ab initio calculations. The results are explained by using a variable coupling exciton model. Coherence effects in a model two-level system with trap are examined …
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Spectroscopic Studies on the Impact of Defects in Hybrid Organic-Inorganic Perovskites on Charge Carrier Dynamics and Photovoltaic Device Performance
… and the use of this characterization, along with time-resolved spectroscopy, to better understand the influence of carrier dynamics on solar cell device performance. We observed that a decrease in device fill factor corresponded to an increase in trap state density and a change in the trapping …
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Exciton and Energy Transfer Dynamics in Hybrid Perovskite and Lanthanide Nanomaterials
… the lowest-energy states and they show long lifetimes and diffusion lengths. However, triplet excitons are dark states. This makes harvesting triplet energy for optoelectronic applications difficult. This thesis focuses on fundamental study on: 1) Understanding the exciton dynamics in …
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Exciton Dynamics in DNA-Chromophore Assemblies
… parameters in directing electronic energy. Using time-resolved spectroscopy, we show how chromophore placement within a tunable DNA scaffold can be used to independently control both electronic coupling and system-bath coupling, and furthermore identify their roles in mediating exciton transport. …
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The application of GHz bandwidth electrical pulses to a single semiconductor quantum dot.
… Static voltages were applied over single dots. Time-resolved spectroscopy allows the identification of hole tunnelling from the dot to the capping layer-superlattice interface. Suppression of hole tunnelling is achieved by altering the wafer structure. Autocorrelation measurements exhibit a …
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Luminescence studies of the excitonic system in germanium: Phase properties and transport
… system in Ge. These studies employ near-infrared spectroscopy and imaging techniques to examine the phase and transport properties of the low temperature exciton-plasma system. The first study, presented in Chapter II, examines the properties of the electron-hole liquid (EHL) phase as a function …
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Mechanisms of Flavin-Dependent Monooxygenases Involved in Natural Product Chemistry
… kinetics were measured using anaerobic time-resolved spectroscopy. All three enzymes feature a fast flavin reduction step and a slow flavin dehydration step. The oxygenation chemistry of each enzyme was found to proceed through a highly reactive oxygenating species, the …
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Shining light on the photoexcited states of first-row transition metal photocatalysts
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-05-01
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Ultrafast Spectroscopy of Organic Semiconductors: Singlet Fission and Nonfullerene Acceptors for Organic Photovoltaics
… charge transfer state. Transient absorption spectroscopy allowed us to examine singlet fission in films of pentacene, fluorinated pentacene, and coevaporated blends of various mixing ratios. We directly observe an intermolecular charge transfer state during singlet fission in solid films of …
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Coherent Terahertz Control and Ultrafast Spectroscopy of Layered Antiferromagnets
… possible by ultrafast lasers with femtosecond time resolution. These advancements not only showcase the capability of ultrafast experiments in understanding complex material properties but also demonstrate the manipulation of ordered phases at ultrafast timescales, thereby opening a laboratory …
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