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.
Results
Showing 1 to 20 of 51 for “"ultrafast spectroscopy"”.
-
Ultrafast spectroscopy and control of correlated quantum materials
… on correlated condensed matter systems using ultrafast optics. I begin with a broad overview of this field, focusing specifically on the essential physics involved in ultrafast processes and how that physics may be utilized, in the sense of either spectroscopy or control, to understand …
-
Coherent Terahertz Control and Ultrafast Spectroscopy of Layered Antiferromagnets
… observing responses in others, made 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 …
-
Charge Carrier Dynamics of Lead Halide Perovskites Probed with Ultrafast Spectroscopy
In this thesis, we investigate the nature of charge carrier generation, relaxation and recombination in a range of lead halide perovskites. We focus on understanding whether the photophysical behaviour of these perovskite materials is like that of highly-ordered inorganic crystalline semiconductors …
-
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 …
-
Dynamics of Energy Carriers in Solids During Interaction with Ultrafast Laser Pulses
… in terms of the energy-carrier dynamics. ^ Ultrafast spectroscopy is a powerful tool to examine the dynamics of energy carriers, which excites a transient response of the material by a short laser pulse and detects the response by optical observables such as reflectance and transmittance. …
-
Theory and Simulations of Charge Transfer in Engineered Chemical Systems
… dynamics, were combined with synthesis, ultrafast spectroscopy and conductance measurements to design and characterize engineered chemical systems for efficient charge and energy transfer.</p><p>Compelling foundational questions explored in this dissertation include: 1) Can we control the …
-
Ultrafast Probing of Nonlinear Dynamics in Quantum Materials: Beyond Linear Response Probes
… features still under debate. Recent advances in ultrafast laser technology have made it possible to study the dynamical behavior of solids that remains hidden to equilibrium probes. Novel spectroscopy techniques, such as coherent phonon spectroscopy, transient absorption spectroscopy, second …
-
Overcoming Efficiency Limits in Photovoltaic Devices
… success and the decision was taken to move to ultrafast spectroscopy. In examining quantum dot films using picosecond transient absorption spectroscopy, we found clear signatures of carrier multiplication occurring in films of dots synthesis here. We also found that some of our results were at …
-
Coherent lattice and molecular dynamics in ultrafast single-shot spectroscopy
… and application of dual- echelon single-shot ultrafast spectroscopy to the study of coherent nuclear motion in condensed phase systems. The general principles of the single-shot method are described, and particular emphasis is given to the general applicability and shortcomings of this …
-
Photophysical transformations in molecules studied by ultrafast multi-pulse spectroscopy /
… systems by the means of transient absorption spectroscopy. First two chapters are dedicated to the theoretical background, the description of the objects of the study and the experimental tools used. The following three chapters correspond to three different systems explored by ultrafast …
-
Molekulių fotofizikinių virsmų tyrimas ultrasparčiosios daugiaimpulsės spektroskopijos metodais /
… systems by the means of transient absorption spectroscopy. First two chapters are dedicated to the theoretical background, the description of the objects of the study and the experimental tools used. The following three chapters correspond to three different systems explored by ultrafast …
-
Photochemistry, photophysics and spectroscopy of redox states of flavins relevant to photoactive flavoproteins
… with the visible to mid-IR transient absorption spectroscopy. Ground and excited state frequencies of the characteristic carbonyl modes are observed and assigned with the aid of DFT calculations. Moreover, the stable neutral radical flavin has been prepared for study in aqueous solution, and both …
-
Magneto-Optical Effects in Manganese-doped Lead Halide Perovskite
… Employing spin resonance and magneto-optical spectroscopy, we find coupling between the dopant’s magnetic moment and the exciton spin of the semiconductor. We report magnetic brightening of a dark exciton population by state mixing with the bright excitons at cryogenic temperatures. We show …
-
Development of Broadband Time-Resolved Spectroscopy and Investigation of the Dynamics of Photoexcited Carriers and Lattice Excitations in Chiral Weyl Semimetals
… 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 based upon a …
-
Light-Harvesting, Redox Control, and Biomimicry of the Photosynthetic Antennas of Green Sulfur Bacteria
… of the BChl a molecules in the protein using ultrafast spectroscopy. We show that the system undergoes intersystem crossing into the triplet state after ~25% of excitations, and the lifetime of the triplet state is between 10-100 μs. We also, using electrochemistry and mass spectrometry, …
-
To Couple or not to Couple? Exploring Vibronic Coupling in Organic Semiconductors
… in organic semiconductors using a combination of ultrafast spectroscopy, vibrational analysis, and molecular design. While each chapter presents a self-contained study, together they address a unified question: how can we suppress or exploit exciton–phonon interactions to enhance the efficiency of …
-
Ultrafast and Nonlinear Spectroscopy of Colloidal Nanomaterials
… absorption is also used to investigate the ultrafast excited-state relaxation dynamics of the different dyes adsorbed on the core-shell-shell surface and the size-dependent dynamics o interfacial charge transfer between the gold nanoclusters and the TiO2 bandgap in TiO2-Au nanocomposites. In …
-
Ultrafast Terahertz Spectroscopy of Collective Excitations in Correlated Materials
… collective excitations in solids is through ultrafast spectroscopy. In this technique, an intense, ultrashort “pump” laser pulse drives the material out of equilibrium, and a subsequent weaker “probe” pulse detects the altered state of the system. By tailoring the parameters of the pump …
-
Heterogeneous Ultrafast Energy Transfer in Photosynthetic Proteins
… experiments to measure rates relied on ensemble ultrafast spectroscopy, which is limited to average values. With single-molecule approaches, we can overcome the limitations of ensemble averaging by measuring individual proteins. However, single-molecule experiments have been primarily restricted …
-
Nanoparticle-nanoparticle interactions and light-matter interaction studied by simulated absorption spectroscopy
… is studied by simulated transient absorption spectroscopy using real-time time-dependent density functional theory calculations. Finally, nanoclusters Au₂₅ and Au₃₈ are also studied by ab initio transient absorption spectroscopy calculations. This dissertation represents the first time that …
Page 1 of 3