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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Tvorba a spektroskopická charakterizace chladných molekul a molekulárních radikálů v supersonické plazmatické trysce / Creation and characterization of cold molecules and molecular radicals in supersonic plasmatic nozzle

Mašát, Milan January 2013 (has links)
Title: Creation and characterization of cold molecules and molecular radicals in supersonic plasmatic nozzle Author: Milan Mašát Department: J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i. (32-UFCHAV) Supervisor: Mgr. Ondřej Votava, Ph. D., J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i. (32-UFCHAV) Abstract: The aim of this work is the development and characterization of experimental apparatus designed for study of expansion-cooled stable and unstable molecule species in near infrared region, as well as associated methodology. This device consists of discharge source of cold molecular radicals and a system for their spectroscopic analysis. The source and the spectroscopic part changes and upgrades are described in detail. Characterization of radical source and its methodology was done on the OH radical model. Changes in radical properties under different experimental conditions, such as stagnation pressure, used voltage and different geometries of both the nozzle and electrodes are measured. Methodology of spectroscopic analysis was carried out on methane molecule in unassigned part of spectra, so called icosad region. Keywords: supersonic expansion, molecular radical source, high resolution spectroscopy
42

Spectroscopy and Dynamics of Small Molecules with Large Amplitude Motion

Dawadi, Mahesh B. 11 September 2014 (has links)
No description available.
43

Keck Planet Imager and Characterizer: concept and phased implementation

Mawet, D., Wizinowich, P., Dekany, R., Chun, M., Hall, D., Cetre, S., Guyon, O., Wallace, J. K., Bowler, B., Liu, M., Ruane, G., Serabyn, E., Bartos, R., Wang, J., Vasisht, G., Fitzgerald, M., Skemer, A., Ireland, M., Fucik, J., Fortney, J., Crossfield, I., Hu, R., Benneke, B. 26 July 2016 (has links)
The Keck Planet Imager and Characterizer (KPIC) is a cost-effective upgrade path to the W.M. Keck observatory (WMKO) adaptive optics (AO) system, building on the lessons learned from first and second-generation extreme AO (ExA0) coronagraphs. KPIC will explore new scientific niches in exoplanet science, while maturing critical technologies and systems for future ground-based (TMT, FELT, GMT) and space-based planet imagers (HabEx, LUVOIR). The advent of fast low-noise IR cameras (IR-APD, MKIDS, electron injectors), the rapid maturing of efficient wavefront sensing (WFS) techniques (Pyramid, Zernike), small inner working angle (IWA) coronagraphs (e.g., vortex) and associated low-order wavefront sensors (LOWFS), as well as recent breakthroughs in high contrast high resolution spectroscopy, open new direct exoplanet exploration avenues that are complementary to planet imagers such as VLT-SPHERE and the Gemini Planet Imager (GPI). For instance, the search and detailed characterization of planetary systems on solar-system scales around late-type stars, mostly beyond SPHERE and GPI's reaches, can be initiated now at WMKO.
44

A espectroscopia de alta resolução em sólidos por RMN aplicada ao estudo de compostos híbridos sílica-polipropilenoglicol-LiClO4 condutores iônicos e do polímero condutor eletrônico poliparafenileno dopado com FeCl3 / Solid-state NMR high-resolution spectroscopy and relaxation applied to the study of hybrid ion conducting compounds silica/polypropylene-LiClO4 and electronic conducting polymer poly(para-phenylene) doped with FeCl3

Souza, Paulo Henrique de 27 February 1998 (has links)
Neste trabalho estudamos duas classes diferentes de materiais condutores através de várias técnicas: o polímero condutor eletrônico Poliparafenileno (PPP) dopado com FeCl3, e os compostos condutores iônicos orgânico-inorgânico complexados com LiClO4, chamados ormolitas. Um estudo comparativo de PPP dopado com FeCl3, por RMN de Alta Resolução em Sólidos de 13C , Ressonância Paramagnética Eletrônica, Susceptibilidade Magnética e Condutividade Elétrica foi realizado em função da concentração de Fe e da temperatura. Observou-se uma forte influência do íon paramagnético Fe3+ na largura de linha e nos tempos de relaxação spin-rede medidos por RMN de alta resolução através do 13C. OS resultados obtidos pelos diferentes métodos estão correlacionados e podem ser explicados pelo modelo polaron-bipolaron. Duas famílias de ormolitas, foram preparadas pelo processo sol-gel. Um estudo comparativo destes compostos por RMN de alta resolução multinuclear, Calorimetria Diferencial (DSC) e Condutividade Elétrica foi feito em função da concentração de lítio, do comprimento da cadeia polimérica, da razão polímero-sílica e da temperatura. Através das medidas de largura de linha dos espectros de RMN em função da temperatura, para os núcleos de 7Li e 13C, podemos observar uma forte correlação entre RMN, DSC e Condutividade Elétrica. Estes resultados confirmam que a condutividade iônica do lítio é governada pela mobilidade dos segmentos da cadeia polimérica, sendo esta responsável pela modulação das barreiras eletrostáticas nos sítios do íon Li+ / In this work we investigated two different classes of conducting materials using several techniques: the electronic conducting polymer FeC13-doped Polyparaphenylene (PPP) and the ionic conducting LiC1O4-complexed organic-inorganic nanocomposites called ormolytes. A comparative study of the FeC13, doped polyparaphenylene (PPP) by the 13C High-Resolution Solid-State NMR, Electron Paramagnetic Resonance (ESR), Magnetic Susceptibility, and electrical conductivity was made as a function of the iron concentration and the temperature. It is observed that a clear correlation among the results obtained from different methods takes place as a function of iron doping and temperature. which can be explained by polaron-bipolaron model and the presence of the paramagnetic ion Fe3+. Two families of hybrid organic-inorganic composites exhibiting ionic conduction properties, so called ORMOLYTES, have been prepared by the sol-gel process. A comparative study of these composites by the multinuclear High-Resolution Solid-State NMR, Differential Scanning Calorimetry (DSC), and electrical conductivity was made as a function of the lithium concentration, polymer chain length, polymer to silica ratio and the temperature. It was observe a strong correlation between NMR, DSC and electrical conductivity and this result corroborate the fact that the Li+ ionic conductivity is governed by the polymer chain mobility
45

Spectroscopic study of acetylene and hydrogen cyanide

Rozario, Hoimonti Immaculata January 2012 (has links)
High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213–333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole–quadrupole and pairwise atom–atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1νl20←0νl20 band system from the HCN emission spectrum. The infrared emission spectrum of H12C14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters. / viii, 112 leaves : ill. ; 29 cm
46

A espectroscopia de alta resolução em sólidos por RMN aplicada ao estudo de compostos híbridos sílica-polipropilenoglicol-LiClO4 condutores iônicos e do polímero condutor eletrônico poliparafenileno dopado com FeCl3 / Solid-state NMR high-resolution spectroscopy and relaxation applied to the study of hybrid ion conducting compounds silica/polypropylene-LiClO4 and electronic conducting polymer poly(para-phenylene) doped with FeCl3

Paulo Henrique de Souza 27 February 1998 (has links)
Neste trabalho estudamos duas classes diferentes de materiais condutores através de várias técnicas: o polímero condutor eletrônico Poliparafenileno (PPP) dopado com FeCl3, e os compostos condutores iônicos orgânico-inorgânico complexados com LiClO4, chamados ormolitas. Um estudo comparativo de PPP dopado com FeCl3, por RMN de Alta Resolução em Sólidos de 13C , Ressonância Paramagnética Eletrônica, Susceptibilidade Magnética e Condutividade Elétrica foi realizado em função da concentração de Fe e da temperatura. Observou-se uma forte influência do íon paramagnético Fe3+ na largura de linha e nos tempos de relaxação spin-rede medidos por RMN de alta resolução através do 13C. OS resultados obtidos pelos diferentes métodos estão correlacionados e podem ser explicados pelo modelo polaron-bipolaron. Duas famílias de ormolitas, foram preparadas pelo processo sol-gel. Um estudo comparativo destes compostos por RMN de alta resolução multinuclear, Calorimetria Diferencial (DSC) e Condutividade Elétrica foi feito em função da concentração de lítio, do comprimento da cadeia polimérica, da razão polímero-sílica e da temperatura. Através das medidas de largura de linha dos espectros de RMN em função da temperatura, para os núcleos de 7Li e 13C, podemos observar uma forte correlação entre RMN, DSC e Condutividade Elétrica. Estes resultados confirmam que a condutividade iônica do lítio é governada pela mobilidade dos segmentos da cadeia polimérica, sendo esta responsável pela modulação das barreiras eletrostáticas nos sítios do íon Li+ / In this work we investigated two different classes of conducting materials using several techniques: the electronic conducting polymer FeC13-doped Polyparaphenylene (PPP) and the ionic conducting LiC1O4-complexed organic-inorganic nanocomposites called ormolytes. A comparative study of the FeC13, doped polyparaphenylene (PPP) by the 13C High-Resolution Solid-State NMR, Electron Paramagnetic Resonance (ESR), Magnetic Susceptibility, and electrical conductivity was made as a function of the iron concentration and the temperature. It is observed that a clear correlation among the results obtained from different methods takes place as a function of iron doping and temperature. which can be explained by polaron-bipolaron model and the presence of the paramagnetic ion Fe3+. Two families of hybrid organic-inorganic composites exhibiting ionic conduction properties, so called ORMOLYTES, have been prepared by the sol-gel process. A comparative study of these composites by the multinuclear High-Resolution Solid-State NMR, Differential Scanning Calorimetry (DSC), and electrical conductivity was made as a function of the lithium concentration, polymer chain length, polymer to silica ratio and the temperature. It was observe a strong correlation between NMR, DSC and electrical conductivity and this result corroborate the fact that the Li+ ionic conductivity is governed by the polymer chain mobility
47

The SALT HRS Spectrograph

Tyas, Luke Martin Graham January 2012 (has links)
SALT HRS (Southern African Large Telescope High Resolution Échelle Spectrograph) is a high-resolution, high-efficiency spectrograph for the 11m SALT telescope in Sutherland, South Africa. The initial optical design work was performed at the University of Canterbury, New Zealand. Revisions to the concept, the mechanical design, manufacture, assembly and testing have been handled by the Centre for Advanced Instrumentation, at Durham University in the United Kingdom. SALT HRS is a fibre-fed echelle grating spectrograph with four operational modes: low-, medium- and high-resolution and high-stability modes, having spectral resolutions of R ≈16000, 37000, 67000 and 67000 respectively over a wavelength range of 370-890nm. The instrument is of a dual channel, ‘white pupil’ design, in which the primary mirror acts to collimate light onto a single R4 echelle grating, and also to focus dispersed light to an intermediate focus. A dichroic beam-splitter separates the dispersed light into two separate spectral channels. Spherical pupil mirrors transfer the separated beams via a fold mirror to two wavelength-specific volume-phase holographic gratings (VPHGs) used as cross-dispersers. Cross-dispersed spectra are then imaged by two fully dioptric camera systems onto optimized CCD detectors. This thesis presents the results of the laboratory testing and specification of several critical sub-systems of SALT HRS, as well as the development of key software tools for the design verification and operation at the telescope. In Chapter 1 we first review the technical development of high-resolution spectroscopy and its specific implementation in SALT HRS. In Chapter 2 we develop a comprehensive throughput model of the entire system based on a combination of as-built performance and specific throughput measurements in the laboratory. This is used to make some specific predictions for the on-sky performance of SALT HRS and the magnitude limits for science targets. We also present a graphical exposure time calculator based on these measurements which can be used by an astronomer to plan their observations with SALT HRS. Chapter 3 contains a detailed treatise on the optical fibre system of SALT HRS. Considerations for the use of optical fibres in astronomy are provided, as are details of an optional double scrambler, and the various instrument fibre modes. Extensive measurements of focal ratio degradation (FRD) are also presented, with testing of input beam speed; wavelength; fibre bending; variable pupil mirror illumination; and vacuum tank pressure dependency. The systems for fibre management are reviewed, as is the fibre bundle assembly process. Testing of two further sub-systems is described in Chapter 4. Firstly the long-term stability of the mirror mounting mechanisms is determined. The advantages of cross-dispersion of echelle spectra using volume-phase holographic gratings are then discussed, and the results of diffraction efficiency measurements are given for both red and blue channel gratings. Modern CCD technologies are examined in Chapter 5, and the blue detector is experimentally characterized using photon transfer and quantum efficiency curves. It is also used for an investigation into cosmic ray events in CCDs. Results from shielding the detector using lead are described, as is an attempt to distinguish the source of the events based on their morphology. Finally, Chapter 6 deals with the handling of data produced by SALT HRS. Methods of wavelength calibration of the spectra are discussed, including the use of Thorium-Argon lamps and an iodine absorption cell. The implementation of a Python based quick-look data reduction pipeline is reviewed, with a description of the processes performed. A summary of the thesis is given in Chapter 7.
48

Two Near-Infrared Spectroscopic Studies of Ultracool Dwarfs: A Proper Motion Survey Follow-Up and A High-Resolution Investigation

Greco, Jennifer J. January 2020 (has links)
No description available.
49

Wavelength Discrimination for Spectroscopy and Spectral Imaging Using a Phased Array

Damsel, Jonathan R. January 2019 (has links)
No description available.
50

Geoacoustic inversion in laterally varying shallow-water experiments using high-resolution wavenumber estimation

Becker, Kyle M January 2002 (has links)
Thesis (Ph. D. in Applied Ocean Sciences)--Joint Program in Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), February 2002. / Includes bibliographical references (leaves 161-170). / Sound propagation in shallow water is highly dependent on the interaction of the sound field with the bottom. In order to fully understand this problem, it is necessary to obtain reliable estimates of bottom geoacoustic properties that can be used in acoustic propagation codes. In this thesis, perturbative inversion methods and exact inverse methods are discussed as a means for inferring geoacoustic properties of the bottom. For each of these methods, the input data to the inversion is the horizontal wavenumber spectrum of a point-source acoustic field. The main thrust of the thesis work concerns extracting horizontal wavenumber content for fully three-dimensionally varying waveguide environments. In this context, a high-resolution autoregressive (AR) spectral estimator was applied to determine wavenumber content for short aperture data. As part of this work, the AR estimator was examined for its ability to detect discrete wavenumbers in the presence of noise and also to resolve closely spaced wavenumbers for short aperture data. As part of a geoacoustic inversion workshop, the estimator was applied to extract horizontal wavenumber content for synthetic pressure field data with range-varying geoacoustic properties in the sediment. The resulting wavenumber content was used as input data to a perturbative inverse algorithm to determine the sound speed profile in the sediment. It was shown using the high-resolution wavenumber estimator that both the shape and location of the range-variability in the sediment could be determined. / (cont.) The estimator was also applied to determine wavenumbers for synthetic data where the water column sound speed contained temporal variations due to the presence of internal waves. It was shown that reliable estimates of horizontal wavenumbers could be obtained that are consistent with the boundary conditions of the waveguide. The Modal Mapping Experiment (MOMAX), an experimental method for measuring the full spatial variability of a propagating sound field and its corresponding modal content in two-dimensions, is also discussed. The AR estimator is applied to extract modal content from the real data and interpreted with respect to source/receiver motion and geometry. For a moving source, it is shown that the wavenumber content is Doppler shifted. A method is then described that allows the direct measure of modal group velocities from Doppler shifted wavenumber spectra. Finally, numerical studies are presented addressing the practical issues associated with using MOMAX type data in the exact inversion method of Gelfand-Levitan. / by Kyle M. Becker. / Ph.D.

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