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 57 for “"absorption features"”.
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Rotationally resolved visible spectroscopy of the Asteroid 1 Ceres
… to support/refute the previous findings about absorption features within the wavelength range being observed. Additionally, this thesis was designed to determine the rotational variability of minerals on Ceres. In order to determine the asteroid's variablity, the rotational period of Ceres was …
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Surface detection of alkaline ultramafic rocks in semi-arid and arid terrains using spectral geological techniques
… to determine if they had diagnostic spectral absorption features. These studies demonstrated that there are diagnostic spectral absorption features common to alkaline and other ultramafic rocks including dunite, peridotite and serpentinite. The diagnostic spectrum in the SWIR2 region (2000nm …
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X-ray absorption by the intergalactic medium
… via the so-called "X-ray Forest" the X-ray absorption lines produced by the hot IGM. I gave a semi-analytic calculation of the X-ray forest distribution based on the Press-Schechter formalism. The warm-hot intergalactic medium - the IGM between 10⁵ - 10⁷ K - was investigated via hydrodynamic …
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DeMeo taxonomy : categorization of asteroids in the near-infrared
… a larger data range, which includes important absorption features at one and two microns suggesting the presence of minerals, there is a need for an extended system to encompass this range of information. In this work we explain the process of creating the taxonomy, the method for finding an …
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Investigating the presence and properties of circumstellar material in Type I Supernovae
… statistical excess of narrow, blueshifted Na I D absorption features and the presence and strength of high velocity Ca II near infrared triplet absorption features, have been suggested to be produced as a result of interaction between the ejecta of the supernova with circumstellar material located …
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Excitons in the thallous halides
… exceptional sharpness, Previously undiscovered absorption features have appeared and exciton effects have been established. A variety of experiments were performed to clarify the nature of the structure associated with the first exciton peak. Intrinsic structure and structure due to strain …
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Ground-based transmission spectroscopy of three inflated Hot Jupiter exoplanets
… have been successful in the detection of several absorption features in the optical wavelength range. These are for example a Rayleighscattering slope and absorption by sodium and potassium. However, other objects show a featureless spectrum indicative for a cloud or haze layer of condensates …
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The variability of warm absorbers in Active Galactic Nuclei
… Strong line emission without corresponding absorption indicates significant WA geometric structure. Strong absorption features in the spectrum are evidence of a highly-ionized, high-velocity outflow, which could be carrying a large amount of mass and energy out of the AGN. In the second …
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The Evolution of Massive Young Stellar Objects in the Large Magellanic Cloud
… Evidenced by their very different spectral features, the luminous objects span a range of evolutionary states from those most embedded in their natal molecular material to those that have dissipated and ionized their surroundings to form compact HII regions and photodissociation regions. We …
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Characterising Exoplanet Atmospheres with High-Resolution Transmission Spectroscopy
… task when observing from the ground since absorption from Earth’s atmosphere often overwhelms the exoplanetary signals by several orders of magnitude. I compare the performance of corrections made using a telluric spectrum derived empirically from airmass and using a model of Earth’s …
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Growth of unsaturated, cyclic, and polycyclic aromatic hydrocarbons: Reactions under the conditions of the interstellar medium
… infrared (IR) emission and ultraviolet (UV) absorption features. Yet, their origin in dense phases of the interstellar medium (ISM), such as molecular clouds, remains unclear. In this work, growth mechanisms based on ion-molecule reactions between cationic PAHs/hydrocarbons and methyne (CH) …
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Quantum Cascade Laser Frequency Combs
… By mixing two different frequency combs, absorption features at optically frequencies can be encoded into the radio-frequency domain, eliminating the need for expensive, high-frequency detectors. This "dual-comb spectrometer" offers a chip-scale alternative to bulky spectrometers, making …
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Improving nanosatellite capabilities for atmospheric sounding and characterization
… channels across bands centered on atmospheric absorption features. MWRs require stable cold and warm calibration targets for accurate measurements. CubeSat MWRs, such as MicroMAS (the Micro-sized Microwave Atmospheric Satellite) and MiRaTA (Microwave Radiometer Technology Acceleration), use …
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Vibrational dynamics of aqueous hydroxide solutions studied using ultrafast infrared spectroscopy
… and other strong bases exhibit a broad continuum absorption for frequencies between 800 and 3500 cm-¹, which is attributed to the strong interactions of the hydroxide ion with its solvating water molecules. This continuum absorption has limited distinguishable features whose molecular origin holds …
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Aluminum-hydride formation in the relaxation zones following shock waves in the atmosphere of long-period variable stars
… velocities, which has been observed. Any AlH absorption features which are detected should be red-shifted.</p>
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Optical Studies of Ordered Monomolecular Layers: Ab Initio Simulation and Experiment
… ground state, optimal geometry and the optical absorption features. A 530 nm absorption band is obtained to conclude the properties of the Q3CNQ LB layers, and also used to compare with our own experimental results.
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Data Analysis in Global 21-cm Experiments: Chromatic Effects and Signal Reconstruction
… signal model designed to capture potential features arising from unexpected physics. The work is carried out within the framework of the REACH experiment and its data analysis pipeline. Part I includes two chapters. Chapter 1 provides an introduction to 21-cm cosmology, and outlines both …
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Seyfert and starburst activity in galaxies: Modeling and analysis
… analysis in the infrared, using stellar absorption features. These tools are ideally suited for studies of dusty galaxies and obscured stars in the Milky Way. We used the CO band at 2.3μm to estimate the contribution from red supergiants to the total K-band flux in the central regions of …
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Revealing the Nature of Exoplanetary Atmospheres
… passes in front, or transits, its parent star, absorption features are imprinted into starlight passing through the planetary atmosphere. By analysing the resultant transmission spectrum, one can reveal the chemical composition of these distant worlds. Already, this technique has yielded …
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Properties of Galaxies Detected in Emission and Absorption with Background Quasars
… primordial gas. However, it is unclear how these absorption systems relate to present day galaxies. Observations of these systems detected through absorption in background quasar spectra indicate the DLAs are metal poor and slowly evolving while their counterparts, the sub-DLAs, are highly …
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