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 28 for “"THz Spectroscopy"”.
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Developments in THz Polaritonics: Towards Integrated Nonlinear THz Spectroscopy
The terahertz (THz) polaritonics platform is a compact, waveguide-based platform for the generation, manipulation, and detection of THz waves. The platform uses thin (<100 μm) lithium niobate (LiNbO₃, LN) and lithium tantalate (LiTaO₃, LT) slabs, which can be patterned to control THz propagation. …
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Characteristics of nanocomposites and semiconductor heterostructure wafers using THz spectroscopy
All optical, THz-Time Domain Spectroscopic (THz-TDS) methods were employed towards determining the electrical characteristics of Single Walled Carbon Nanotubes, Ion Implanted Si nanoclusters and Si_{1-x}Ge_x HFO_2, SiO_2 on p-type Si wafers. For the nanoscale composite materials, Visible Pump/THz …
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Measurement of gas flow through porous structures using thz spectroscopy
Comparing THz transmission through a sample with the transmission through free-space allows one to calculate the THz absorbance of a sample. Previous studies have focused on using THz absorbance to measure the diffusion of liquid through materials. In this study, the ability of THz spectroscopy to …
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Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics
This thesis develops phonon-polariton based THz spectroscopy and uses this technique to make the first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). THz spectroscopy has emerged as an important probe for a wide variety of …
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Study of ultrafast polarization and carrier dynamics in semiconductor nanostructures : a THz spectroscopy approach
… in semíconductor nanostructures is studied using THz emission and optical-pump THz probe spectroscopy. A theoretical model of dynamical screening of an optically excited biased quantum well is developed.
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Terahertz-field-induced nonlinearity in phonons, electrons and spins
… responses initiated by strong terahertz (THz) field excitation. I discuss two aspects of nonlinear THz spectroscopy in condensed-matter materials: developments of experimental THz capabilities and spectroscopy methods and their applications in investigating ultrafast nonlinear dynamics in …
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Developments and advances in nonlinear terahertz spectroscopy
Nonlinear terahertz (THz) spectroscopy is a rapidly developing field, which is concerned with driving and observing nonlinear material responses in the THz range of the electromagnetic spectrum. In this thesis, I present several advances in nonlinear THz spectroscopy that expand the range of …
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Time-Resolved THz Magnetospectroscopy: Techniques and Applications
Ultrafast terahertz (THz) spectroscopy has been advanced by a research effort that includes technique development as a central focus. Multiple paradigm-shifting breakthroughs in experimental techniques have emerged in recent decades, including optical pump/THz probe spectroscopy, THz polaritonics, …
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Phonon polariton interaction with patterned materials
The generation, propagation and detection of THz phonon polaritons are studied through both femtosecond pump-probe techniques, and Finite Difference Time Domain (FDTD) simulations in this thesis. The theory surrounding the driving, propagation and detection of these modes is treated in a consistent …
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Towards terahertz dual-comb spectroscopy based on quantum cascade lasers
In this thesis, terahertz (THz) laser frequency combs are improved and THz dual-comb spectroscopy method is demonstrated. To achieve better performance of THz quantum cascade laser (QCL) frequency combs, several broadband homogeneous and heterogeneous gain media are characterized, and corresponding …
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Two-dimensional terahertz rotational spectroscopy in the gas phase
Two-dimensional (2D) coherent spectroscopy has been developed to study molecular dynamics and structures for decades, but its extension into the terahertz (THz) regime remains rare. In this thesis, I describe several experiments using two-dimensional terahertz rotational spectroscopy. Employing …
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Developments in time-resolved ultrafast imaging and spectroscopy at terahertz frequencies
… femtosecond lasers, the field of terahertz (THz) spectroscopy was stagnated by the lack of both high power THz sources and sensitive THz detectors. Over the past few years, it has become more 'routine' to generate and detect THz radiation between 0.1-10 THz, but there remains much room for …
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Dynamics of lattice vibrations, molecular rotations and spins studied by terahertz spectroscopy
In this thesis, I describe generation of strong THz electromagnetic pulses with broad bandwidths or tailored waveforms using organic nonlinear optical crystals and spectroscopy experiments utilizing THz pulses to study the linear and nonlinear responses of molecular dipole, spin, and lattice …
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Electrically tunable terahertz quantum cascade lasers
… tunable terahertz quantum cascade lasers (THz QCLs) are designed and demonstrated. Two MEMS tuner devices are proposed to achieve electrically tunable THz QCLs. One is the electrostatic comb drive actuated tuner design and the other one is a two-stage flexure design that is actuated by an …
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Terahertz response of microfluidic-jetted fabricated 3D flexible metamaterials
… techniques to construct metamaterials in THz range via a material deposition system. The metamaterials are fabricated by stacking alternative layers with conventional designs such as single ring- split ring resonators (SRR) and microstrips to form a 3D metamaterial structure. Conductive …
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Novel characterization of materials using THz spectroscopic techniques
… and technical challenges within the terahertz (THz) frequency regime have recently motivated an array of new research activities. This involves numerous applications of this region of the electromagnetic spectrum between approximately 100 GHz (3mm) and 3 THz (100 um) for both spectroscopy and …
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Evaluation of Non-Covalent Interaction Models in Molecular Crystals Using Terahertz Spectroscopy
… of solid-state crystalline materials. Since THz spectroscopy is sensitive to both the intermolecular and intramolecular forces that govern the formation of crystalline materials, it is an ideal tool to investigate the accuracy of calculated DFT crystal structures and their vibrational …
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The Solid State Simulation of the Structure and Vibrational Modes of Organic, Hybrid Organometallic and Inorganic Species Using the CRYSTAL09 Code.
… the polymorphs of vanadium phosphate, terahertz (THz) spectroscopy was used to probe the intermolecular interactions in these molecular crystals. These studies aim to increase the understanding of what effect subtle structural, compositional, or packing differences have on the vibrational normal …
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Photoinduced Dynamics Studied using Single-Shot Optical and Terahertz Spectroscopy
… ultrafast single-shot optical and terahertz (THz) spectroscopy to study irreversible photoinduced dynamics and materials far from equilibrium. First, we motivate the understanding of photoinduced material responses as initiated by, and probed with, ultrafast laser pulses, including the …
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Broadband THz time-domain spectroscopy of biomolecules : a comprehensive study of the dielectric properties of biomaterials in the far-infrared
Since the introduction of THz-time-domain spectroscopy (THz-TDS) in the late 1980's, the technique, based on the generation and detection of subpicosecond terahertz pulses, has found widespread use as a simple and versatile experiment technique for obtaining the low frequency response of gases, …
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