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Dissertations / Theses on the topic 'Spectroscopy'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 November 2024

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1

Woods, Stephan M. "VIBRATIONAL SPECTROSCOPY AND SPECTROSCOPIC IMAGING OF BIOLOGICAL CELLS AND TISSUE." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1322540287.

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2

Cordova, Clay Alexander. "Supersymmetric Spectroscopy." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10345.

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We explore supersymmetric quantum field theories in three and four dimensions via an analysis of their BPS spectrum. In four dimensions, we develop the theory of BPS quivers which provides a simple picture of BPS states in terms of a set of building block atomic particles, and basic quantum mechanical interactions. We develop efficient techniques, rooted in an understanding of quantum-mechanical dualities, for determining the spectrum of bound states, and apply these techniques to calculate the spectrum in a wide class of field theories including ADE gauge theories with matter, and Argyres-Douglas type theories. Next, we explore the geometric content of quivers in the case when the four-dimensional field theory can be constructed from the six-dimensional (2; 0) superconformal field theory compactified on a Riemann surface. We find that the quiver and its superpotential are determined by an ideal triangulation of the associated Riemann surface. The significance of this triangulation is that it encodes the data of geodesics on the surface which in turn are the geometric realization of supersymmetric particles. Finally we describe a class of three-dimensional theories which are realized as supersymmetric domain walls in the previously studied four-dimensional theories. This leads to an understanding of quantum field theories constructed from the six-dimensional (2; 0) superconformal field theory compactified on a three-manifold, and we develop the associated geometric dictionary. We find that the structure of the field theory is determined by a decomposition of the three-manifold into tetrahedra and a braid which species the relationship between ultraviolet and infrared geometries. The phenomenon of BPS wall-crossing in four dimensions is then seen in these domain walls to be responsible for three-dimensional mirror symmetries.
Physics

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3

Massé, Kunal. "MR Spectroscopy : Real-Time Quantification of in-vivo MR Spectroscopic data." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9825.

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In the last two decades, magnetic resonance spectroscopy (MRS) has had an increasing success in biomedical research. This technique has the faculty of discerning several metabolites in human tissue non-invasively and thus offers a multitude of medical applications. In clinical routine, quantification plays a key role in the evaluation of the different chemical elements. The quantification of metabolites characterizing specific pathologies helps physicians establish the patient's diagnosis. Estimating quantities of metabolites remains a major challenge in MRS. This thesis presents the implementation of a promising quantification algorithm called selective-frequency singular value decomposition (SELF-SVD). Numerous tests on simulated MRS data have been carried out to bring an insight on the complex dependencies between the various components of the data. Based on the test results, suggestions have been made on how best to set the SELF-SVD parameters depending on the nature of the data. The algorithm has also been tested for the first time with in-vivo 1H MRS data, in which SELF-SVD quantification results allow the localization of a brain tumor.

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4

Brewster, Victoria Louise. "Investigating protein modifications using vibrational spectroscopy and fluorescence spectroscopy." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/investigating-protein-modifications-using-vibrational-spectroscopy-and-fluorescence-spectroscopy(32ff24c8-326a-41cf-a076-11e067376525).html.

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Protein based biopharmaceuticals are becoming increasingly popular therapeutic agents. Recent changes to the legislation governing stem cell technologies will allow many further developments in this field. Characterisation of these therapeutic proteins poses numerous analytical challenges. In this work we address several of the key characterisation problems; detecting glycosylation, monitoring conformational changes, and identifying contamination, using vibrational spectroscopy. Raman and infrared spectroscopies are ideal techniques for the in situ monitoring of bioprocesses as they are non-destructive, inexpensive, rapid and quantitative. We unequivocally demonstrate that Raman spectroscopy is capable of detecting glycosylation in three independent systems; ribonuclease (a model system), transferrin (a recombinant biopharmaceutical product), and GFP (a synthetically glycosylated system). Raman data, coupled with multivariate analysis, have allowed the discrimination of a glycoprotein and the equivalent protein, deglycosylated forms of the glycoprotein, and also different glycoforms of a glycoprotein. Further to this, through the use of PLSR, we have achieved quantification of glycosylation in a mixture of protein and glycoprotein. We have shown that the vibrational modes which are discriminatory in the monitoring of glycosylation are relatively consistent over the three systems investigated and that these bands always include vibrations assigned to structural changes in the protein, and sugar vibrations that are arising from the glycan component. The sensitivity of Raman bands arising from vibrations of the protein backbone to changes in conformation is evident throughout the work presented in this thesis. We used these vibrations, specifically in the amide I region, to monitor chemically induced protein unfolding. By comparing these results to fluorescence spectroscopy and other regions of the Raman spectrum we have shown that this new method provides improved sensitivity to small structural changes. Finally, FT-IR spectroscopy, in tandem with supervised machine learning methods, has been applied to the detection of protein based contaminants in biopharmaceutical products. We present a high throughput vibrational spectroscopic method which, when combined with appropriate chemometric modelling, is able to reliably classify pure proteins and proteins ‘spiked’ with a protein contaminant, in some cases at contaminant concentrations as low as 0.25%.

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5

Drezek, Rebekah Anna. "The biophysical origins of cervical tissue fluorescence and reflectance spectra modeling, measurements, and clinical implications /." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3031044.

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6

Kallir, Alan J. "Total luminescence spectroscopy /." [S.l.] : [s.n.], 1986. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=7960.

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7

Gagnon, Justin. "Attosecond Electron Spectroscopy." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-125375.

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8

Bernhardt, Birgitta. "Dual Comb Spectroscopy." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-134357.

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9

Andrews, Django H. "Anion photoelectron spectroscopy." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239380.

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10

Willetts, Andrew. "Theoretical vibrational spectroscopy." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358853.

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11

Allcock, S. C. "Resonant particle spectroscopy." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379878.

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12

Bucher, Dominik. "Femtosecond vibrational spectroscopy." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-180061.

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13

Numan, Nagla Numan Ali. "Terahertz (THz) spectroscopy." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71690.

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Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Terahertz radiation is currently used in security, information and communication technology (ICT), and biomedical sciences among others. The usability of terahertz (THz) radiation, in many of its applications depends on characteristics of the materials being investigated in the THz range. At the heart of THz usage is a THz spectroscopy system necessary for the generation and detection of the THz radiation. In this thesis, we characterise such a THz spectroscopy system. In our typical THz spectrometric system, we make use of femtosecond (fs) laser technology and pump-probe principles for emission and detection of THz radiation. Background about the principles of generation THz radiation using fs triggered antennas and the principles of the spectroscopy technique and appropriate literature references are presented. Using an assembled commercially available kit, we reproduce known spectra in order to confirm correct functionality (for calibration) of the assembled spectroscopy system and to gain experience in interpreting these spectra. By introducing a suitable x - y scanning device we construct a crude THz imaging device to illustrate the principle.
AFRIKAANSE OPSOMMING: Terahertsstraling word deesdae wyd in die sekuriteits, inligting-en-kommunikasie en biomediese sektore aangewend. Die gepastheid van terahertsstraling (THz) vir ’n spesifieke toepassings hang af van die eienskappe van die materiale wat ondersoek word. Vir die uitvoer van sulke eksperimente word ’n THz-spektroskopie sisteem benodig vir die opwekking en meting van THz-straling. In hierdie tesis word so ’n THz-spektroskopie sisteem beskou en gekarakteriseer. In die sisteem word van ’n femtosekondelaser (fs) gebruik gemaak in ’nn pomp-en-proef opstelling vir die uitstraling en meting van THz-straling. Die beginsels rakende die opwekking van THz-straling, deur gebruik te maak van ’n antenna wat deur ’n fs-laser geskakel word, asook die beginsels van die spektroskopiese tegniek, met toepaslike verwysings, word in die tesis aangebied. Deur gebruik te maak van’n kommersiële THz opstelling is bekende spektra gemeet om die korrekte funksionering (vir kalibrasie doeleindes) na te gaan en om ondervinding op te doen in die interpretasie van hierdie spektra. ’n X-Y-translasie toestel is tot die opstelling bygevoeg om THz-afbeelding moontlik te maak en sodoende hierdie beginsel te illustreer.

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14

Kirstein, Johanna, Christophe Jung, Christian Hellriegel, and Christoph Bräuchle. "Single molecule spectroscopy." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196553.

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15

Chao, Karl 1960. "Modulated emittance spectroscopy." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276977.

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The electronic bandstructure of solids near room temperature has been successfully explored with previous versions of modulation spectroscopy. Modulation of parameters which enter into the bandstructure produce a dielectric function variation. This changes the optical observables, such as reflectance or absorptance. Modulation resonances are observed near singularities in the joint density-of-states function. These resonances must also be detectable in the emittance, an observable which also depends on the dielectric function. Thus, this work investigates the possibility of detection of optical resonances riding on the temperature derivative of the blackbody emission from a solid at high temperature. The modulated emittance was separated from the thermal background by a detection scheme utilizing a CCD and computer. The resonances were not observed because of excessive CCD noise. The existance and magnitude of the resonances was based upon results from other modulation spectroscopies.

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16

Janni, James A. (James Alan) 1970. "Vibrational Kerr spectroscopy." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/28203.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1998.
Includes bibliographical references.
The infrared vibrational Kerr effect was investigated as a potentially selective and sensitive detection method for explosives. The investigation of the vibrational Kerr effect commenced with the first reported measurement of the integrated infrared vapor absorption strengths for the explosives trinitrotoluene, (TNT), cyclotrimethylene trinitramine (RDX), and pentaerythritrol tetranitrate (PETN). From the infrared absorption spectra, the characteristic N02 symmetric and asymmetric stretch bands of the explosives were identified as spectral targets for the vibrational Kerr effect. The vibrational Kerr spectra of fluoroform and nitromethane were successfully measured with conventional Kerr techniques. The vibrational Kerr measurements were first made on the CH stretch-bend combinations of fluoroform around 7000 cm7'. The remainder of the vibrational Kerr measurements were carried out on the N02 asymmetric stretch band of nitromethane at 15 84 nf '. Nitromethane was an ideal test molecule of the infrared measurement system because of its similarity to the eplosives and its large room temperature vapor pressure. Rotationally resolved Kerr spectra of nitromethane were recorded for segments of the asymmetric stretch band and the expected qualitative features of the Kerr spectra were observed. Although the sensitivity needed for the detection of explosives was not demonstrated, the selective detection of polar molecules over weakly polar molecules was demonstrated for a mixture of nitromethane and nitrogen dioxide. The methods investigated for measurement of the Kerr effect in both the infrared and ultraviolet spectral regions are described in detail. Polarization modulation of the light source with phase sensitive detection was expected to increase sensitivity to the Kerr effect over conventional Kerr techniques. Despite the anticipated sensitivity enhancement offered by polarization modulation, poor performance of the photoelastic modulators and the Fourier Transform spectrometer impeded the demonstration of the enhancement
by James A. Janni.
Ph.D.

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17

Dayal, A. R. (Austin Robinson). "SF6 arc spectroscopy." Phd thesis, School of Engineering, 1991. http://hdl.handle.net/2123/7359.

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18

SPARAPASSI, GIORGIA. "Femtosecond Covariance Spectroscopy." Doctoral thesis, Università degli Studi di Trieste, 2020. http://hdl.handle.net/11368/2960841.

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In order to reveal a signal arising from a nonlinear interaction, several spectroscopic techniques are nowadays adopted. In spite of their practical and fundamental differences, they have in common to rely on pulse to pulse consistency to deliver information on a nonlinear process. With the work presented in this thesis we show, instead, that we can successfully leverage upon experimental noise. To achieve this goal, we exploited the fact that a weak nonlinear signal introduces a strong spectral correlation, which can be revealed even when the output spectra fully spectrally and spatially overlap with the excitation pulse. Based on these principles, we proposed a novel approach to a nonlinear spectroscopy experiment, called Femtosecond Covariance Spectroscopy. To provide a solid basis for the validation of the technique, we focused on a third order nonlinear process, inelastic light scattering, which is prompted by the mixing of intense electric fields in a transparent material. The interaction implies that the measured intensity at some point in the transmitted spectrum is statistically related to the intensity at other points of the spectrum, whenever their energy distance coincides with an energy level of the sample involved in the scattering. We performed inelastic light scattering experiments from vibrational modes of a benchmark sample, quartz. We employed a near infrared laser with central wavelength in a transparency region of the sample, and bandwidth larger than its lowest energy vibrational modes. We found in the correlation coefficient sidebands that reproduce the vibrational spectrum of the sample. Their lineshape changes according to the presence or absence of a non modulated portion of the spectrum, heterodyning the scattered radiation. In fact we find that a partial spectral randomization is most efficient in preparing a pulse with no pre-existent correlation, that, at the same time, provides a local oscillator for the sample-induced fluctuations to be amplified. In this scheme, the ultrashort pulse provides, at the same time, intense electric fields to stimulate a response, and noninteracting components to reveal it. The self-heterodyned nature of the acquisition is accounted for in a fully quantum model. The technique can be adapted to a pump - probe scheme by exciting the sample with a separate, intense and spectrally coherent, pump pulse. Our measurements of the average transmitted probe intensity performed using a pump to excite coherent vibrational states, reveal that oscillations in the response are initiated in-phase by the pump and evolve at the vibrational frequencies. Such a response is an ideal candidate to test a covariance based probe, as the spectrum undergoes a red-shift or a blue-shift alternatively in time, and the correlation coefficient is found to oscillate in time at the phonon frequency. The investigation we started with this Thesis aims, primarily, at establishing the signatures in the correlation that resolve a thermal from a coherent vibrational state. In fact, if a quantum optics model describes accurately the results of a standard pump probe experiment on quartz, the theoretical framework must be completed in order to describe a pump probe approach employing randomized pulses and a covariance based retrieval. The experiments have shown that consistent information is present in the correlation maps, but more incisive analytical and conceptual tools are needed to assess the different contributions. The proposed method has proven to be a powerful probing scheme in a optical spectroscopy experiment, and can be successfully translated into the language of stochastic X-ray pulses, complex materials, electronic scattering processes. To fully characterize the FCS technique there are still steps to take. Nonetheless we believe that the present work sets the basis for the development of a technique that successfully conveys information beyond traditional schemes.

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19

Ronningen, Theodore J. "Low temperature helium pressure broadening of HCN." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1118153531.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xiv, 218 p.; also includes graphics (some col.) Includes bibliographical references (p. 208-218). Available online via OhioLINK's ETD Center

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20

Burkart, Johannes. "Optical feedback frequency-stabilized cavity ring-down spectroscopy - Highly coherent near-infrared laser sources and metrological applications in molecular absorption spectroscopy." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY045/document.

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La spectroscopie d'absorption moléculaire est un outil incontournable non seulement pour la physique fondamentale et la métrolgie mais aussi pour des domaines aussi divers que les sciences environnementales, la planétologie ou l'astrophysique. Ces dernières années, des techniques spectroscopiques qui exploitent l'amplification résonnante d'interaction entre lumière laser et molécules dans une cavité optique ont fourni des détectivités exceptionnelles sur l'axe d'absorption, tandis que l'axe de fréquence des spectromètres n'atteignait généralement pas le même niveau de précision.Dans cette thèse, nous avons répondu à ce défi en développant la spectroscopie en cavité par temps de déclin stabilisée en fréquence par rétroaction optique (OFFS-CRDS en anglais). Cette nouvelle technique présente une combinaison unique de stabilité et résolution fréquentielles sub-kHz, d'un niveau d'intensité lumineuse intra-cavité de l'ordre du kW/cm^2, d'une detectivite de 2 x 10^(−13) cm^(−1)Hz^(-1/2) limitée par le bruit de photons, et d'une limite de détection de 8.4 x 10^(−14) cm^(−1) sur une plage spectrale étroite. Ces performances inédites sont dues à l'asservissement de la cavité spectroscopique à un laser balayé en fréquence par modulation à bande latérale unique et stabilisé par rétroaction optique avec une cavité en V de réference ultrastable. Pour transférer la cohérence de ce laser sub-kHz à des lasers plus bruiteux dans d'autres gammes spectrales à travers un peigne de fréquence optique, nous avons exploré une nouvelle méthode de clonage de phase par une correction anticipative à large bande passante et démontré une erreur résiduelle de phase de 113 mrad. En appliquant l'OFFS-CRDS à la spectroscopie du CO2 à 1.6 μm, nous avons obtenu un spectre large bande avec une dynamique de 8 x 10^5, et nous avons déterminé douze fréquences de transition absolues avec une exactitude de l'ordre du kHz en mesurant des Lamb dips sub-Doppler en absorption saturée avec un dispositif équipé d'un peigne de fréquence. Par ailleurs, nous avons procédé à une analyse détaillée des sources d'erreurs systematiques en CRDS et nous avons déduit une formule analytique pour le déclin de cavité non-exponentiel dans un régime faiblement saturé qui est susceptible de contribuer à de futures mesures de moments de transition dipolaire indépendantes de la concentration. Nos résultats ouvrent des perspectives prometteuses pour des applications métrologiques de l'OFFS-CRDS, comme par exemple l'étude de profils de raie poussés, la mesures de rapports isotopiques et la spectroscopie d'absorption saturée extensive dans le proche infrarouge
High-precision molecular absorption spectroscopy is a powerful tool for fundamental physics and metrology, as well as for a broad range of applications in fields such as environmental sciences, planetology and astrophysics. In recent years, spectroscopic techniques based on the enhanced interaction of laser light with molecular samples in high-finesse optical cavities have provided outstanding detection sensitivities on the absorption axis, while the spectrometer frequency axis rarely met as high precision standards.In this thesis, we addressed this challenge by the development of Optical Feedback Frequency-Stabilized Cavity Ring-Down Spectroscopy (OFFS-CRDS). This novel technique features a unique combination of sub-kHz frequency resolution and stability, kW/cm^2-level intracavity light intensity, a shot-noise limited absorption detectivity down to 2 x 10^(−13) cm^(−1)Hz^(-1/2), as well as a detection limit of 8.4 x 10^(−14) cm^(−1) on a narrow spectral interval. This unprecedented performance is based on the tight Pound-Drever-Hall lock of the ring-down cavity to a single-sideband-tuned distributed-feedback diode laser which is optical-feedback-stabilized to a highly stable V-shaped reference cavity. To transfer the coherence of this sub-kHz laser source to noisier lasers in other spectral regions through an optical frequency comb, we have explored a novel high-bandwidth feed-forward phase cloning scheme and demonstrated a residual phase error as low as 113 mrad. Applying OFFS-CRDS to the spectroscopy of CO_2 near 1.6 μm, we obtained a broadband spectrum with a dynamic range of 8 x 10^5 and retrieved twelve absolute transition frequencies with kHz-accuracy by measuring sub-Doppler saturated absorption Lamb dips with a comb-assisted setup. Furthermore, we have performed a comprehensive analysis of systematic error sources in CRDS and derived an analytic formula for the non-exponential ring-down signal in a weakly saturated regime, which may contribute towards future concentration-independent transition dipole moment measurements. Our results open up promising perspectives for metrological applications of OFFS-CRDS, such as advanced absorption lineshape studies, isotopic ratio measurements and extensive saturated absorption spectroscopy in the near infrared

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21

Khalaf, Shhab Ahmed Abdolah. "Spectroscopy and dynamics of small molecules using laser and microwave spectroscopy." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296535.

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22

Popa, Emil Horia. "Algorithms for handling arbitrary lineshape distortions in Magnetic Resonance Spectroscopy and Spectroscopic Imaging." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00716176.

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Magnetic Resonance Spectroscopy (MRS) and Spectroscopic Imaging (MRSI) play an emerging role in clinical assessment, providing in vivo estimation of disease markers while being non-invasive and applicable to a large range of tissues. However, static magnetic field inhomogeneity, as well as eddy currents in the acquisition hardware, cause important distortions in the lineshape of acquired NMR spectra, possibly inducing significant bias in the estimation of metabolite concentrations. In the post-acquisition stage, this is classically handled through the use of pre-processing methods to correct the dataset lineshape, or through the introduction of more complex analytical model functions. This thesis concentrates on handling arbitrary lineshape distortions in the case of quantitation methods that use a metabolite basis-set as prior knowledge. Current approaches are assessed, and a novel approach is proposed, based on adapting the basis-set lineshape to the measured signal.Assuming a common lineshape to all spectral components, a new method is derived and implemented, featuring time domain local regression (LOWESS) filtering. Validation is performed on synthetic signals as well as on in vitro phantom data. Finally, a completely new approach to MRS quantitation is proposed, centred on the use of the compact spectral support of the estimated common lineshape. The new metabolite estimators are tested alone, as well as coupled with the more common residual-sum-of-squares MLE estimator, significantly reducing quantitation bias for high signal-to-noise ratio data.

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23

Kok, Trina. "Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78450.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis. Page 94 blank.
Includes bibliographical references (p. 87-93).
While magnetic resonance imaging (MRI) derives its signal from protons in water, additional biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of these much weaker signals is known as magnetic resonance spectroscopy or spectroscopic imaging. Among the complicating factors for this modality applied to human clinical imaging are limited chemical-shift dispersion and J-coupling, which cause spectral overlap and complicated spectral shapes that limit detection and separation of brain metabolites using MR spectroscopic imaging (MRSI). Existing techniques for improved detection include so-called 2D spectroscopy, where additional encoding steps aid in the separation of compounds with overlapping chemical shift. This is achieved by collecting spectral data over a range of timing parameters and introducing an additional frequency axis. While these techniques have been shown to improve signal separation, they carry a penalty in scan time that is often prohibitive when combined with MRSI. Beyond scan time constraints, the lipid signal contamination from the subcutaneous tissue in the head pose problems in MRSI. Due to the large voxel size typical in MRSI experiments, ringing artifacts from lipid signals become more prominent and contaminate spectra in brain tissue. This is despite the spatial separation of subcutaneous and brain tissue. This thesis first explores the combination of a 2D MRS method, _Constant Time Point REsolved SpectroScopy (CT-PRESS) with fast spiral encoding in order to achieve feasible scan times for human in-vivo scanning. Human trials were done on a 3.OT scanner and with a 32-channel receive coil array. A lipid contamination minimization algorithm was incorporated for the reduction of lipid artifacts in brain metabolite spectra. This method was applied to the detection of cortical metabolites in the brain and results showed that peaks of metabolites, glutamate, glutamine and N-acetyl-aspartate were recovered after successful lipid suppression. The second task of this thesis was to investigate under-sampling in the indirect time dimension of CT-PRESS and its associated reconstruction with Multi-Task Bayesian Compressed Sensing, which incorporated fully-sampled simulated spectral data as prior information for regularization. It was observed that MT Bayesian CS gave good reconstructions despite simulated incomplete prior knowledge of spectral parameters.
by Trina Kok.
Ph.D.

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24

Li, Zhenghong. "The role of the counter rotating terms in spontaneous emission and the time evolution of lamb shift." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1419.

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25

Li, Jianping. "High-resolution UV-Vis-NIR fourier transform imaging spectroscopy and its applications in biology and chemistry." HKBU Institutional Repository, 2010. http://repository.hkbu.edu.hk/etd_ra/1151.

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26

Khong, Yoon Loong. "Solid state spectroscopy : laser spectroscopy of praseodymium doped mixed alkaline earth fluorides." Thesis, University of Canterbury. Physics, 1991. http://hdl.handle.net/10092/8068.

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The defect centers formed in the double alkaline earth crystals Ca₁₋ₓSrₓF₂ : Pr⁳⁺ Cₐ₋ₓBaₓF₂:Pr⁳⁺, Sr₁₋ₓCaₓF₂ : Pr⁳⁺ and Sr₁₋ₓBaₓF₂ : Pr⁳⁺for x ＞ 0.02% , together with the deuterated versions of these crystals, were investigated using selective laser excitation. All crystals were doped with 0.01% Pr⁳⁺. The mixed crystal centers in these systems are derived from the prominent C₂ center in the parent CaF₂ : Pr⁳⁺ and Sr F₂ : Pr⁳⁺ crystals by the replacement of the host alkaline earth cations in the neighbourhood cation spheres of the Pr⁳⁺ ion by the dopant alkaline earth. Three fluorine centers for each of the Sr⁲⁺ and Ba⁲⁺ doped CaF₂ : Pr⁳⁺ crystals and two and one centers for the Ca⁲⁺ and Ba⁲⁺ doped SrF₂: Pr⁳⁺ crystals respectively were studied in detail. For the deuterated crystals, two centers were studied for each of the mixed crystal systems. From the total of 17 centers investigated, four common polarization characteristics were apparent and these were used to classify the centers as types A1, A2, A3 or A4. On the basis of the observed polarised fluorescence, the A1 and A2 centers are found to be consistent with having a Cs and C4v symmetry respectively and models were proposed for these centers accordingly. Ambiguities in the spectroscopic data prevented a presentation of definite models for the A3 and A4 centers. Temporal studies in the form of lifetime measurements were performed on these mixed crystal centers and crystal field trends from these studies are presented. Crystal field fits were attempted for some of the C4v centers. Though the results from the fits are tentative at the moment, problems and possible solutions are identified. The bleaching characteristics of the lower symmetry hydrogenic centers, known as bleaching centers, were studied. Results from the polarization studies here appear to support models previously assigned to the parent bleaching centers. The satellite centers associated with the parent bleaching centers are characterised and discussions of models for these centers are presented.

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27

Yang, Shilong 1975. "Theoretical study of single-molecule spectroscopy and vibrational spectroscopy in condensed phases." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30237.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.
Includes bibliographical references (p. 267-279).
In this thesis, theoretical models and computer simulations are employed to study several problems of single-molecule spectroscopy and vibrational spectroscopy in condensed phases. The first part of the thesis concentrates on studying dynamic disorders probed by single molecule fluorescence spectroscopy. Event statistics and correlations of single-molecule fluorescence sequences of modulated reactions are evaluated for multi-channel model, diffusion-controlled reaction model, and stochastic rate model. Several event-related measurements, such as the on-time correlation and the two-event number density, are proposed to map out the memory function, which characterizes the correlation in the conformational fluctuations. A semiflexible Gaussian chain model is used to determine the statistics and correlations of single-molecule fluorescence resonant energy transfer (FRET) experiments on biological polymers. The distribution functions of the fluorescence lifetime and the FRET efficiency provide direct measures of the chain stiffness and their correlation functions probe the intra-chain dynamics at the single-molecule level. The fluorescence lifetime distribution is decomposed into high order memory functions that can be measured in single- molecule experiments. The scaling of the average fluorescence lifetime on the contour length is predicted with the semi-flexible Gaussian chain model and agrees favorably with recent experiments and computer simulations.
(cont.) To interpret the fluorescence measurements of the mechanical properties of double-stranded DNA, a worm-like chain model is used as a first-principle model to study double-stranded DNA under hydrodynamic flows. The second part of the thesis concentrates on nonperturbative vibrational energy relaxation (VER) effects of vibrational line shapes. In general, nonperturbative and non-Markovian VER effects are demonstrated more strongly on nonlinear vibrational line shapes than on linear absorption.
by Shilong Yang.
Ph.D.

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28

Ekvall, Karin. "Time resolved laser spectroscopy." Doctoral thesis, KTH, Physics, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3063.

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29

Miroshnichenko, Andrey. "Spectroscopy of Discrete Breathers." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1070455053031-79847.

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30

Nicovich, Philip R. "Widefield fluorescence correlation spectroscopy." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33849.

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Fluorescence correlation spectroscopy has become a standard technique for modern biophysics and single molecule spectroscopy research. Here is presented a novel widefield extension of the established single-point technique. Flow in microfluidic devices was used as a model system for microscopic motion and through widefield fluorescence correlation spectroscopy flow profiles were mapped in three dimensions. The technique presented is shown to be more tolerant to low signal strength, allowing image data with signal-to-noise values as low as 1.4 to produce accurate flow maps as well as utilizing dye-labeled single antibodies as flow tracers. With proper instrumentation flows along the axial direction can also be measured. Widefield fluorescence correlation spectroscopy has also been utilized to produce super-resolution confocal microscopic images relying on the single-molecule microsecond blinking dynamics of fluorescent silver clusters. A method for fluorescence modulation signal extraction as well as synthesis of several novel noble metal fluorophores is also presented.

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31

Przybilla, Norbert. "QUANTITATIVE SPECTROSCOPY OF SUPERGIANTS." Diss., lmu, 2002. http://nbn-resolving.de/urn:nbn:de:bvb:19-820.

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32

Wirth, Adrian. "Attosecond transient absorption spectroscopy." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-140120.

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33

Skjeie, Hans Christian Bakken. "Terahertz Time-Domain Spectroscopy." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19214.

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The field of terahertz time-domain spectroscopy (THz-TDS) is still far from reaching its full potential, but is a very promising utility for a wide range of applications. Principle experiments have been performed in fields of drug screening, pharmaceutical, medical diagnostics, security imaging and detection of explosives. Optimized and adapted THz-TDS systems holds great promise for driving this technology further.The purpose of this thesis was to build a THz-TDS system, explore possibilities for improving this system and to perform THz-TDS measurements on semiconductors and wood. The aim of the experimental work was to build a stable and reliable system with an electric field strength of THz radiation in the order of kV/cm. The THz-TDS system used in this thesis was based upon the principles of optical rectification and free-space electro-optic sampling in zinc telluride (ZnTe) crystals using a femtosecond Ti:Sapphire amplified laser.Theoretical studies were performed on the principles of generation and detection of THz radiation. The experimental work was based on publications of similar experiments. Theoretical and experimental studies lead to several modifications and improvements of the setup first built in this thesis. Experiments were performed on disparate materials to find suitable materials for THz transmission. Results from measurements performed on semiconductors and wood, obtained by THz-TDS, were analysed to find the absorption coefficient and the refractive index of the materials. The spectroscopic information obtained by THz-TDS can also be used to find the conductivity and the mobility of these materials. THz-TDS measures the electric field and therefore provides information of both the amplitude and the phase of the THz wave. A Fourier transformation was used to obtain the frequency spectrum of the detected signal. The improvements were done by analysing the results of the detected signal to see which adjustments and modifications to the setup that had positive effects on the results. The pump power used for generation of THz radiation and the optimum azimuthal angle of the ZnTe crystals were crucial to obtain a THz-TDS system with a strong electric field. The maximum electric field strength for the THz radiation in this thesis was 13.2 kV/cm, with a signal-to-noise ratio of 43 and dynamic range of 1500.

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34

Hollingworth, Andrew Roy. "Semiconductor optoelectronic infrared spectroscopy." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/842674/.

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We use spectroscopy to study infrared optoelectronic inter and intraband semiconductor carrier dynamics. The overall aim of this thesis was to study both III-V and Pb chalcogenide material systems in order to show their future potential use in infrared emitters. The effects of bandstructure engineering have been studied in the output characteristics of mid-IR III-V laser diodes to show which processes (defects, radiative, Auger and phonon) dominate and whether non-radiative processes can be suppressed. A new three-beam pump probe experiment was used to investigate interband recombination directly in passive materials. Experiments on PbSe and theory for non-parabolic near-mirror bands and non-degenerate statistics were in good agreement. Comparisons with HgCdTe showed a reduction in the Auger coefficient of 1-2 orders of magnitude in the PbSe. Using Landau confinement to model spatial confinement in quantum dots (QDs) "phonon bottlenecking" was studied. The results obtained from pump probe and cyclotron resonance saturation measurements showed a clear suppression in the cooling of carriers when Landau level separation was not resonant with LO phonon energy. When a bulk laser diode was placed in a magnetic field to produce a quasi quantum wire device the resulting enhanced differential gain and reduced Auger recombination lowered Ith by 30%. This result showed many peaks in the light output which occurred when the LO phonon energy was a multiple of the Landau level separation. This showed for the first time evidence of the phonon bottleneck in a working laser device. A new technique called time resolved optically detected cyclotron resonance, was used as a precursor to finding the earner dynamics within a spatially confined quantum dot. By moving to the case of a spatial QD using an optically detected intraband resonance it was possible to measure the energy separation interband levels and conduction and valence sublevels within the dot simultaneously. Furthermore this technique has been shown that the inhomogeneous broadening of the photoluminescence spectrum is not purely affected by just size and composition. We suggest that other processes such as state occupancy, In roughing, and exciton binding energies may account for the extra energy.

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35

Pogson, Mark. "High pressure vibrational spectroscopy." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/33858.

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The study of solids at high pressure and variable temperature enables development of accurate interatomic potential functions over wide ranges of interatomic distances. A review of the main models used in the determination of these potentials is given in Chapter one. A discussion of phonon frequency as a variable physical parameter reflecting the interatomic potential is given. A high pressure Raman study of inorganic salts of the types MSCN, (M = K,Rb,Cs & NH4+) and MNO2, (M = K,Na) has been completed. The studies have revealed two new phases in KNO2 and one new phase in NaNO2 at high pressure. The accurate phonon shift data have enabled the determination of the pure and biphasic stability regions of the phases of KNO2. A discussion of the B1, B2 relationship of univalent nitrites is also given. In the series of thiocyanates studied new phases have been found in all four materials. In both the potassium and rubidium salts two new phases have been detected, and in the ceasium salt one new phase has been detected, all at high pressure, from accurate phonon shift data. These transitions are discussed in terms of second-order mechanisms with space groups suggested for all phases, based on Landau's theory of second-order phase transitions. In the ammonium salt one new phase has been detected. This new phase transition has been interpreted as a second-order transition. The series of molecular crystals CH3HgX, (X = Cl,Br & I) has been studied at high pressure and at variable temperature. In Chapter five, their phase behaviour at high pressure is detailed along with the pressure dependencies of their phonon frequencies. In the chloride and the bromide two new phases have been detected. In the bromide one has been detected at high temperature and one at high pressure, the latter being interpreted as the stopping of the methyl rotation. In the chloride one phase has been found at both low temperature as well as high pressure, and the other only at high pressure, the latter again associated with the stopping of methyl rotation. The iodide displays two high pressure transitions. A Raman-active soft-mode has been observed in all three analogues, at both high pressure and variable temperature. For the chloride and bromide analogues there is a discussion of the nature of the soft-mode along with the mechanism associated with the I/II transition. The results of the X-ray crystal structure determination of CH3HgBr at ambient temperature and pressure are given.

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36

Judge, Kevin D. "Decision making in spectroscopy /." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3276987.

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37

Schlawin, Frank [Verfasser], and Andreas [Akademischer Betreuer] Buchleitner. "Quantum-enhanced nonlinear spectroscopy." Freiburg : Universität, 2015. http://d-nb.info/1119805635/34.

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38

Savard, Guy. "Saturation spectroscopy of krypton." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63379.

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39

Deeny, J. A. "Tunable diode laser spectroscopy." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253325.

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40

Nichol, A. C. "Infrared spectroscopy of solids." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308601.

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41

Drake, Jeremy J. "High resolution stellar spectroscopy." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236268.

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42

Summerfield, Stephen. "Near infrared fluorescence spectroscopy." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/10601.

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Fluorimetry in the very near infrared region ca. 600-1000nm is a new approach to photochemical analysis. The advantages include greatly reduced background fluorescence signals from important sample matrices (such as blood serum), reduced scattering, and reduced probability of sample decomposition. Also, the availability of low cost, efficient, stable and robust optical components (e.g. laser diodes and light emitting diodes), solid state detectors (e.g. single silicon photodiodes and diode arrays) and fibre optics, allows the construction of an inexpensive fluorimeter. In the near infrared region, there are some very bright fluorophores that can be adapted for use as fluorescent probes, labels for immunoassay, and as ion-pair agents. The advantageous performance of most types of fluorimetric analysis now undertaken In the ultraviolet and visible region of the spectrum may therefore be extended into the longer wavelength region. Excellent limits of detection are attainable, and some near infrared fluorophores show invaluable fluorescence probe properties, such as Nile Red. The most useful of the dye groups investigated were the phenoxazines and thiazines. Reactive derivatives of these dyes show great potential as fluorescent labels for Immunoassay. These dyes have also been used as probes due to their solvatochromism and sensitivity to pH.

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43

Gray-Jones, Craig. "Isomer spectroscopy of ²⁵⁴No." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501596.

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A number of experiments were carried out to clarify the structure and decay path of an isomeric state in ²⁵⁴No [Gh73, He06, Ta06]. A band built on the 1298 keV Kπ = 8- isomer was found. From the observed branching ratios in this band a two-proton configuration is favoured for this state, which further supports our earlier conclusions [He08] that the deformed shell closures in this mass region are at Z = 100 and N = 152, in contradiction to predictions by Skyrme-Hartree-Fock models [Cha06]. Furthermore, the level scheme of ²⁵⁴No was extended to include a floating band and a systematic of reduced hindrance factors for ΔΚ = 8 E1 transitions is given.

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44

Jonathan, P. "Translational spectroscopy of ions." Thesis, Swansea University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637445.

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Translational spectroscopy is used to examine the keV collision reactions of small ions with thermal neutral species. State selective single electron capture data for Ar²⁺ on rare gas and small molecular targets is interpreted in terms of calculated reaction windows and charge exchange channels. Evidence for double ionisation of hydrocarbon targets is presented. Dissociation of H_2⁺ occurs predominantly via direct electronic excitation. A second two collision process involving H₂ intermediates accounting for 5% of H^+ fragment yield is examined; H^- fragments arise from dissociative capture of H_2 intermediates. Approximate relative cross sections, and translational energy release distributions, for H^+ and H^- from the dissociation of H_2^+ in H_2, rare gases and hydrocarbons are measured. An investigation of E/2 mass spectra, involving consecutive charge stripping and electron capture reactions of organic ions, elucidates the parameters governing the reproducibility of spectra. A short study involving benzene, 1,5-hexadiyne, methylbenzene and nitrobenzene demonstrates the effects found. Cations consisting of a rare gas atom associated to a small molecule or radical, are investigated by means of the thermal ion molecule reactions by which they are formed in the ion source of the spectrometer, and their subsequent keV collision reactions. For diatomic dications of this form, charge stripping and charge separation data, discussed in terms of semi empirical potential energy curves, yields valuable information as to ion structure and stability. The design of a novel translational energy spectrometer, capable of an ultimate resolving power of 3 meV on product ion spectra at 500 eV ion translational energy, is described. Matrix calculations for projectile trajectories are performed. A simple theoretical model for inelastic scattering permits the evaluation of the effect of collisional broadening on the resolving power of the instrument.

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45

Hill, Edward George. "Non-LTE plasma spectroscopy." Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542941.

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46

Arita, Yoshihiko. "Multi-mode absorption spectroscopy." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489407.

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A novel approach to absorption spectroscopy is presented which achieves, simultaneously, wide spectral coverage and high spectral resolution. The principle of the technique - dubbed multi-mode absorption spectroscopy (MUMAS) - is described, and demonstrations of the principle are reported using two multi-mode sources: diode lasers and micro-cavity solid state lasers. The technique is shown to have potential for the detection of multiple species and multiple parameters using a single laser and a single detector.

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47

Ideguchi, Takuro. "Nonlinear dual-comb spectroscopy." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-173018.

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48

Ibbett, R. N. "Infrared diffuse reflectance spectroscopy." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382895.

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49

Ferrigato, Alberto. "Spectroscopy of coupled ions." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277517.

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50

Barlow, Stephen J. "Spectroscopy in supercritical fluids." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247570.

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