Dissertations / Theses on the topic 'Ultra spectroscopy'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Ultra spectroscopy.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Newstead, David A. "Photoelectron spectroscopy of ultra-thin metallic layers." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35747.
Full textSemeniuk, Jaroslaw Ivan. "Ultra violet Fourier transform spectroscopy of transition elements." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321659.
Full textManke, Kara Jean. "Toward ultra-broadband photoacoustic spectroscopy of supercooled liquids." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98789.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 163-176).
Theoretical understanding of the dramatic slow-down of structural relaxation dynamics in supercooled liquids leading to the glass transition is limited in part by the lack of data in these systems. Between the melting point and the glass transition, the viscosity of supercooled liquids can change by 16 orders of magnitude or more and few experimental techniques can access this broad a range of frequencies and time scales. Photoacoustic spectroscopy is an ideal technique for probing the dynamics of supercooled liquids because it provides direct access to mechanical relaxation. Currently, photoacoustic spectroscopy of supercooled liquids has been carried out in the range of 10 MHz to 1 GHz with impulsive stimulated light scattering (ISS) and 8 GHz to 200 GHz with picosecond ultrasonics. In this work, I present advances in photoacoustic techniques with the goal of extending the range of frequencies accessible by these methods. To achieve higher-frequency acoustic generation, experiments on semiconductor superlattices (SLs) composed of alternating layers of gallium arsenide (GaAs) and aluminum arsenide (AlAs) and multiple quantum well structures (MQW) of indium gallium nitride (InGaN) and gallium nitride (GaN) as photoacoustic transducers are presented. The results demonstrate that InGaN/GaN SLs can be employed as broadband photoacoustic transducers, generating acoustic frequencies up to 2.5 THz. A simple transient reflectivity technique for the detection and reconstruction of short (- 2 ps) acoustic strain pulses is also presented. Using a time-domain analogue of Brillouin light scattering, data on the acoustic velocity and attenuation rate of supercooled liquid DC704 at frequencies of - 6 GHz and - 12 GHz, a region which can be hard to access with both ISS and PU approaches, is shown. Finally, the slow rise or "Mountain mode" component of ISS signal from DC704, which arises from slow components of the density response at timescales from 10- 4 s to 10- 7 s is examined. Comparison with the broadband compliance spectrum of DC704 demonstrates that the slow rise signal does not directly reflect the relaxing elastic compliance, but contains contributions from other slow degrees of freedom that couple to the density.
by Kara Jean Manke.
Ph. D.
Dick, Susan. "Raman spectroscopy for ultra trace detection of biomolecules." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706455.
Full textHsieh, Chaoray. "Ultra-compact holographic spectrometers for diffuse source spectroscopy." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22533.
Full textCommittee Chair: Adibi, Ali; Committee Member: Chang, Gee-Kung; Committee Member: Ralph, Stephen; Committee Member: Trebino, Rick; Committee Member: Verriest, Erik I.
Jennings, G. "Ultra-violet photoelectron spectroscopy of BCC- and FCC- iron." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306636.
Full textMonk, Stephen David. "Ultra sensitive detection of hydrocarbons using wavelength modulation spectroscopy." Thesis, University of Glasgow, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422654.
Full textPrice, Richard John. "Ultra-high-resolution spectroscopy of the ISM towards Orion." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252156.
Full textKadowaki, Jennifer, Dennis Zaritsky, and R. L. Donnerstein. "Spectroscopy of Ultra-diffuse Galaxies in the Coma Cluster." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623844.
Full textReichmuth, Andreas. "Alkali metal adsorption and ultra-thin film growth." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338308.
Full textSchambach, Philip [Verfasser]. "Tip-enhanced Raman spectroscopy in ultra-high vacuum / Philip Schambach." Berlin : Freie Universität Berlin, 2013. http://d-nb.info/104348079X/34.
Full textVon, Klitzing Wolf Dietrich Carl. "Ultra-high resolution CO₂ laser spectroscopy and transient line narrowing." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627129.
Full textLi, King Fai. "Ultra-fast spectroscopy investigation on organic molecules two photon absorption." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/911.
Full textAdato, Ronen. "Mid-infrared plasmonics for ultra-sensitive spectroscopy of biomolecular interactions." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12705.
Full textMid-infrared (IR) absorption spectroscopy contrasts with numerous other biosensing methods in that it can directly probe molecular structure via bond specific vibrational modes and monitor structural changes even in the absence of any mass transfer. The technique is therefore a valuable tool for a wide range of applications critical for understanding basic biological function and important aspects of e.g. disease progression and treatment. Despite these attractive features, IR absorption spectroscopy is limited as its acquired signal depends on a molecular bonds intrinsic absorption cross-section and path length (via Beers Law). Sensitivity issues therefore restrict applications to a limited set of strong bands and/or relatively thick samples. Additionally, due to the strong absorption of water in theIR, measurements in fluid are cumbersome, requiring specialized equipment and extremely high analyte concentrations. Plasmonic nano-structures supporting resonances at mid-IR wavelengths offer an attractive means with which to overcome many of these limitations. In particular, plasmonic resonances result in strongly enhanced near-field intensities confined to the surface of metallic particles, which allow one to dramatically increase the absorption signal of molecules. This concept is termed SEIRA (Surface Enhanced Infrared Absorption Spectroscopy). This thesis focuses on leveraging IR-resonant plasmonic nanostructures to enable sensitive SEIRA measurements of molecular monolayers, even in aqueous solutions. In achieving this capability, we first develop methods for utilizing nano-particle interactions in engineered arrays and demonstrate their application to the optimal enhancement of protein absorption bands. We then demonstrate multi-band antennas, capable of simultaneously probing several vibrational bands. Thirdly, we present the first demonstrated use of engineered IR antennas for real-time, in-situ IR spectroscopy measurements on a series of protein and nano-particle binding interactions. By leveraging the far-field scattering properties of plasmonic nano-antennas in addition to the associated near-field enhancement and localization, our method enables a unique chip-based spectroscopy technology that is highly compatible with modern sample preparation and handling techniques. Finally, we present a theoretical treatment of the interaction between our engineered resonances and the natural molecular ones. Our general model correctly predicts detailed absorption spectra and a number of effects dependent the experimental setup and plasmonic antenna design.
Syed, Azfar A. "Surface enhanced Raman spectroscopy for ultra-sensitive detection of energetic materials." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4644.
Full textSyed, A. A. "Surface enhanced raman spectroscopy for ultra-sensitive detection of energetic materials." Thesis, Department of Materials and Applied Science, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4644.
Full textHowie, Wendy Helen. "Molecular structure and predissociation dynamics studied using absorption spectroscopy and ion imaging." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364886.
Full textKiwanuka, Ssegawa-Ssekintu. "Supercontinuum radiation for ultra-high sensitivity liquid-phase sensing." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245137.
Full textJohnson, Brian Ivins. "Preparation and Detailed X-Ray Photoelectron Spectroscopy and Spectroscopic EllipsometryAnalysis of Ultrathin Protective Coatings." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8119.
Full textZhao, Yanning. "Hertz-level ultra-stable laser and its application to high precision spectroscopy." kostenfrei kostenfrei, 2009. http://d-nb.info/1000056449/34.
Full textPatterson, Claire Siobhan. "Portable spectroscopy system for ultra-sensitive, real-time measurement of breath ethane." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/538/.
Full textFernandes, Carolina C. "Multinuclear magnetic resonance spectroscopy in the human brain at ultra high-field." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/46607/.
Full textSmith, Richard. "Optical measurement of ultra fine linewidths using artificial neural networks." Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/10418/.
Full textLehec, Henri. "Spectroscopie Rydberg et excitation du coeur isolé d'atomes d'ytterbium ultra-froids." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS566/document.
Full textRydberg atoms offer an ideal platform for the study of long-range interacting systems.However, usual techniques for imaging and trapping are unavailable in alkali Rydberg atoms. Our approach rely on the use of a two-optically-active-valence-electrons atom such as ytterbium. Ionic core transitions of this atom offer new perspecives for optical manipulation in the Rydberg state. However,questions remain open, especially on the possibilities of avoiding the autoionization, process which occurs when the atom is doubly excited.In this thesis, we report on the construction of the experiment, from the cooling and trapping of theatoms to the excitation in Rydberg states. Because of the interactions between valence electrons, the spectroscopy of these highly excited states is relatively complicated. An experimental study, coupled to a multi-channel quantum defect analysis (MQDT) has been done on the s,p,d and f Rydberg series. This study produced an improvement on the precision of the spectroscopy of this series by more than two orders of magnitude. We then studied the isolated core excitationon the 6s1/2 -> 6p1/2 transition for Rydberg states of large orbital quantum numbers (l=5-9). This study showed that auto-ionisation is mostly due to the coupling to the continuum of the 5d3/2 core state. In opposition to the barium atom, where auto-ionisation drops rapidly with the orbital quantum number, we have shown that ytterbium is less favourable to that extent. Thanks to this study we will be able to determine which states are good candidates for the optical manipulation
Marble, Daniel Keith. "Fluorine K-Shell X-Ray Cross Section Measurements for ⁷Li, ¹⁰B, ¹²C, ¹⁴N, and ¹⁶O Ions on Ultra-Clean, Ultra-Thin Yf₃ Solid Target Foils." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc332734/.
Full textAmiri-Hezaveh, A. "Photelectron spectroscopy of ultra-thin epitaxial f.c.c. magnetic films of iron and cobalt." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233668.
Full textRoland, Thomas. "Ultrafast spectroscopy of new organic molecules for photovoltaic applications." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAE009/document.
Full textThe topic of this thesis is the study -through different spectroscopy methods- of new organic molecules for photovoltaic applications. Combination of time resolved fuorescence, time resolved differential absorption and spectro-electro-chemistry with global analysis methods allowed to determine the photo-dynamics of the studied molecules. Two familiesof molecules have been studied. The first one is a donor-type antenna based on the BODIPY dye. The second consists in a donor-acceptor-donor (DAD) triad, with self-organizing properties. After a first generation of molecules that we proved to be limited by a short life time of its charge transfer state (about 55 ps), a second generation of molecules wasdeveloped, including several variation of the donor group, which allowed to study the impact of said variation. Among others, a charge transfer state lifetime longer than 1 nanosecond was observed
Xu, Lei. "Development and application of ultra-sensitive fluorescence spectroscopy and microscopy for biomolecular interaction studies." Doctoral thesis, KTH, Experimentell biomolekylär fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146181.
Full textQC 20140609
Sharshavina, Ksenia. "Nouveaux concepts de filtres spectraux ultra-sélectifs pour spectroscopie embarquée." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30264/document.
Full textGuided Mode Resonance Filters ( GMRF ) are a new generation of narrowband optical filters and are a very promising alternative to conventional multilayer Fabry-Perot filters. The resonance peak of GMRF can be spectrally extremely thin and with a centering wavelength tunable according to the angle of incidence of the light. These properties are particularly important for spectroscopy. Previous works have helped to implement an original structure with two 1D crossed gratings. The performance of this filter overpasses those of conventional filters in their spectral subnanometric response, tunability and their ability to overcome the influence of the polarization of the incident wave under oblique incidence. The aim of this work is to explore the final performances of such devices in terms of resolution and rejection rate, thanks to an approach combining theory, fabrication technology and characterization. We present experimental results of a polarization independent reflective filter, tunable over 40nm with a tunability of 8.3nm / °, having a reflection of 10-3 on a 90nm range outside the resonance and a quality factor over 5000
Butcher, V. A. "Studies of some reactive intermediates in the gas-phase by ultra-violet photoelectron spectroscopy." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381210.
Full textPersuy, Déborah. "Nanoscopie résolue en temps : étude de la réponse spatiale et temporelle pour l'imagerie ultra-rapide." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE016/document.
Full textThis work focuses on developing and modelling far-field spectroscopic methods that couple spatial and time resolutions by using beam-shaping. In a first part, we demonstrate, theoretically and experimentally, that generating a signal in a four-wave mixing experiment performed with Laguerre-Gauss beams, implies the conservation of the total charge of the orbital momentum. We show that this specificity can be used to perform experiments with collinear beams in order to improve spatial resolution. In a second part, we present a time- and spatially-resolved pump-probe technique of our own design: time-resolved imaging is obtained by the interferometric detection of variations in the refraction index of a material, undergone by a wide probe and induced by a diffraction-limited pump-pulse. Improving such an experiment set-up with a spatially-modulated pump-pulse should enable, thanks to the beating between spatial frequencies of sample inhomogeneities and the excitation spatial-modulation, to increase spatial resolution go the Rayleigh criterion
Lelaidier, Tony. "Organic semiconductor characterisation by scanning tunnelling microscopy and optical spectroscopy." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4032/document.
Full textElectronic and self-assembling properties of two organic compound, the DHTAP and the bis-pyrene, have been studied by the means of low temperature scanning tunnelling microscopy (STM) under ultrahigh vacuum conditions. Optical properties have been studied by cavity ring-down (CRD) spectroscopy, also under ultrahigh vacuum conditions.The growth of DHTAP has been studied on different metallic substrate. The growth of bis-pyrene has been studied on Au(111). In each case, the optimal temperature conditions for the formation of a well-ordered first monolayer have been determined. The formation of second monolayers has also been studied. The evolution of the optical properties, studied by CRD, of bis-pyrene deposited on borosilicate glass combined with information obtained from STM allow us to identify these modifications as interactions between transition dipole moments of molecules in the first and in the second layer, and also determine the growth mode.Finally, the possibility to induce chemical modification of DHTAP molecules embedded in an ordered monolayer using the tunnelling current of the STM has been studied. It appears that the molecule embedded in the first ML can be doubly dehydrogenated which leads to the formation of a compound identified as 5,7,12,14-tetraazapentacene (TAP). In the second layer, the formation of two radicals in addition to the TAP has been observed. The TAP molecule is interesting because of that it cannot be synthesized using common organic chemical methods
Gratz, Marcel, and Petrik Galvosas. "Methodical aspects of 2D NMR correlation spectroscopy under conditions of ultra high pulsed field gradients." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193228.
Full textGratz, Marcel, and Petrik Galvosas. "Methodical aspects of 2D NMR correlation spectroscopy under conditions of ultra high pulsed field gradients." Diffusion fundamentals 6 (2007) 6, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14181.
Full textIsaienko, Oleksandr. "Development of ultra-broadband ultrafast infrared sources and applications to nonlinear vibrational spectroscopy of interfaces." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/141408.
Full textPh.D.
Interfaces play a crucial role in the exchange of energy and matter in various physical, chemical and biological systems. A particular interest has been to study interfaces between aqueous phases and various minerals because of their importance in understanding geochemical phenomena as well as for applications such as enhanced oil recovery. The nonlinear optical technique of vibrational sum-frequency generation (SFG) spectroscopy, introduced over 20 years ago, has become a powerful tool to investigate various surfaces, in particular, mineral-water interfaces. One of the challenges of the SFG spectroscopy of aqueous surfaces is the need to tune the central frequency of relatively narrowband IR lasers through the broad range of the OH-stretch frequencies of water molecules (3000 - 4000 cm-1). We have developed a novel ultrabroadband IR laser source that generates infrared pulses in the ~2800-6000 cm-1 range (lambda~3300-1800 nm) with bandwidths Delta(nu)>1000 cm-1, and bandwidths >2000 cm-1 in the near-IR range (lambda~1000-2000 nm). Pulse front tilt of signal pulse has been corrected allowing for compression of signal pulses down to 25 fsec. Such ultrabroadband IR pulses allow us to perform SFG spectroscopy of aqueous surfaces over the entire frequency range of water molecule spectrum (extending from ~2900 cm -1 to ~3800 cm -1) simultaneously, without tuning the laser ("in one shot"). We have used this novel ultrabroadband IR source to investigate the vibrational SFG spectra of silica/water interfaces. The high signal-to-noise ratio of our spectroscopic setup has allowed us to study low-intensity features that were not studied in detail, or recognized previously in the SFG-spectroscopy investigations, including: 1) non-hydrogen bonded OH vibrations at hydrophilic silica/water interfaces; 2) combination [stretch+bend] bands of water at the silica surface appearing at ~5000-5200 cm -1. 3) Overtones of water stretching modes at silica/water interfaces. The most important conclusions from these studies are outlined below. 1. Non-hydrogen bonded hydroxyls at silica/water interface. Typically SFG-studies of mineral/water interfaces (in particular, silica/water) have focused on the most pronounced features - peaks of H-bonded hydroxyls at ~3150 and ~3450 cm -1. We have been able to systematically observe and study a weaker peak at ~3670 - 3700 cm -1. This peak becomes more pronounced as the pH of aqueous phase decreases, as well as the ionic strength increases, indicating that the hydroxyls corresponding to this spectral feature are situated in a very close proximity to the surface. Isotopic dilution experiments indicate that the 3700 cm -1 feature is not due to asymmetric OH stretches as was suggested before. Based on our results, we suggest that this spectral feature corresponds to hydroxyls of water molecules at the silica surface that cannot hydrogen bond with silanol groups because of the lower density of silanols compared to H2O. We believe this to be the first surface-specific study of non-hydrogen bonded hydroxyls at silica, a surface widely accepted as hydrophilic. 2. SFG spectroscopy of [ν(OH)+δ(HOH)] combination bands of water at silica surface. We have extended SFG spectroscopy of the interfacial hydroxyls at mineral/water surfaces into the near-IR frequency range. The studies of overtones of interfacial OH(OD) groups will provide information on the anharmonicity of such species, and thus on the energy of dissociation. In addition, the positions of the overtone frequencies of the hydroxyls are more sensitive to interactions with the environment than the fundamental stretch frequencies. Our particular focus has been to study the stretch+bend combination band nu comb nu;(OH)+delta;(HOH) of liquid water which occurs in the near-IR spectral range at ~5000-5200 cm -1. It is typically much weaker in the FTIR absorption spectra than the fundamental transitions of the OH stretches or HOH bending, similar to overtones of these modes. We have performed, what we believe to be, the first surface-specific vibrational SFG spectroscopic measurements of combination bands of water molecules at silica surfaces. SFG spectroscopy of water combination band allows access to the water bending mode (delta~1600 cm -1), which still has not been observed in sum-frequency.
Temple University--Theses
Qian, Ximei. "Applications of third generation synchrotron radiation in vacuum ultra-violet (VUV) photoionization spectroscopy and dynamics /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Full textHensen, Matthias [Verfasser]. "Concentrating Light: Nano-devices for spectroscopy, ultra-fast current injection and coherent energy transport / Matthias Hensen." Bielefeld : Universitätsbibliothek Bielefeld, 2016. http://d-nb.info/1105645533/34.
Full textMarkmann, Sergej [Verfasser], Nathan [Gutachter] Jukam, and Andreas D. [Gutachter] Wieck. "Ultra-fast spectroscopy of terahertz quantum cascade lasers / Sergej Markmann ; Gutachter: Nathan Jukam, Andreas D. Wieck." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1121909620/34.
Full textChen, Sophia Nan. "X-ray spectroscopy of buried layer foils irradiated with an ultra high intensity short pulse laser." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3352706.
Full textTitle from first page of PDF file (viewed June 16, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 117-126).
Palaniyappan, Sasikumar. "Relativistic rescattering and multi-electron ionization of atoms and molecules in ultra-strong laser fields." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 174 p, 2008. http://proquest.umi.com/pqdweb?did=1597616071&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full textLopez, Kolkovsky Alfredo L. "1H and 31P NMR Spectroscopy for the study of brain metabolism at Ultra High Magnetic Field from Rodents to Men." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112080/document.
Full text1H and 31P nuclear magnetic resonance spectroscopy allows to detect and to measure in vivo and non-invasively the concentrations of biologically relevant compounds associated to metabolic processes such as neurotransmission (glutamate, GABA), neuronal and glial density (N-acetyl-aspartate, myo-inositol) and energetic metabolism (phosphocreatine, ATP) among others. Knowledge of the biochemical profile provides a mean to evaluate the metabolic state of the brain in pathological cases or in evolving physiological conditions, such as aging. Yet, the neural basis of age-related cognitive dysfunction in normal brain aging remains to be elucidated and it has been shown to develop at different rates depending on the structural region.At ultra-high magnetic fields, magnetic resonance spectroscopy (MRS) benefits from an increased signal-to-noise ratio and a higher chemical shift dispersion, resulting in an increased sensitivity and spectral resolution. To exploit these advantages, 1H and 31P longitudinal studies were carried out in vivo at 17.2 Tesla in the aging rat brain to evaluate the progressive metabolic changes within the same individuals from the ages of 1 to up to 22 months of age using two rat cohorts with 1 and 8 months of age at the beginning of the study. For the 1H MRS studies, T1 and T2 metabolite relaxation times were measured at each exam in order to control age-related variations and to calculate absolute metabolite concentrations. 1H neurochemical profiles from four volumes of interest (VOI) in the brain were studied, revealing a progressive increase in myo-inositol and macromolecule content throughout the brain. In our main VOI composed mostly of cortex but also of corpus callosum and hippocampus, increased levels of choline-containing compounds (tCho) and glutamine were also observed, suggesting a mild neuroinflammation. No changes in NAA were observed in our main VOI, the thalamus or the caudate putamen (striatum). T2 decreases were observed with age for total NAA, tCho and macromolecules. Notably, unexpected effects correlated with the number of NMR exams were observed, the most prominent effect being an increase of the T1 relaxation times of the majority of metabolites.The second axis of the work done during this thesis was to set up an experimental framework for MR spectroscopic imaging (MRSI) studies at 7 Tesla in the human brain. 2D MRSI pulse sequences were developed for the acquisition of 31P and 1H metabolite maps using either slab selection or STEAM localization, respectively. A WET water suppression scheme was numerically optimized for its application at 7 T. Static B1-shimming configurations were implemented to reduce the inhomogeneity of the excitation field in the volume of interest and to generate outer-volume suppression (OVS) “ring” modes to saturate the signal in the periphery of the head. This approach allows to reduce the energy deposition in comparison to conventional OVS bands. Experiments were done in vitro showing their feasibility. The performance of standard OVS bands was also compared to a B1-insensitive train to obliterate signal (BISTRO) scheme in vivo using a double-tuned 1H/31P phased-array coil in a single-channel configuration for transmission. The demonstrated suppression efficacy of BISTRO opens the way for its use as a frequency-selective pre-saturation module for future 31P magnetization transfer experiments for the study of brain energy metabolism at very high magnetic field
Fondell, Mattis. "Synthesis and Characterisation of Ultra Thin Film Oxides for Energy Applications." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-232948.
Full textPetersen, Michael. "Laser-cooling of neutral mercury and laser-spectroscopy of the 1So-3 Po optical clock transition." Paris 6, 2009. http://www.theses.fr/2009PA066096.
Full textBohlouli, Zanjani Parisa. "HIGH RESOLUTION MICROWAVE SPECTROSCOPY OF ULTRA COLD RYDBERG ATOMS AS A PROBE OF ELECTRIC AND MAGNETIC FIELDS." Thesis, University of Waterloo, 2003. http://hdl.handle.net/10012/1260.
Full textTombesi, Francesco <1982>. "An X-ray absorption line spectroscopy study of ultra-fast outflows from the innermost regions of AGNs." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2548/.
Full textPadgett, Miles John. "Techniques for ultra-high resolution saturation spectroscopy and laser stabilization in the 10#mu#m spectral region." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305843.
Full textVenkateshwaran, Murali Manohar Saipavitra [Verfasser]. "Quantitative Magnetic Resonance Spectroscopy of Brain Metabolites and Macromolecules at Ultra-High Field / Saipavitra Venkateshwaran Murali Manohar." Tübingen : Universitätsbibliothek Tübingen, 2021. http://nbn-resolving.de/urn:nbn:de:bsz:21-dspace-1190509.
Full textSaule, Tobias [Verfasser], and Ferenc [Akademischer Betreuer] Krausz. "Cavity-enhanced high harmonic generation for multi-MHz ultra-fast photoemission spectroscopy / Tobias Saule ; Betreuer: Ferenc Krausz." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1213245672/34.
Full textHughes, Juanita Maree. "A novel identification method for ultra trace detection of biomolecules using functionalised Surface Enhanced Raman Spectroscopy (SERS)." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/72864/2/Juanita_Hughes_Thesis.pdf.
Full textNilforoushan, Niloufar. "Out-of-equilibrium electron dynamics of Dirac semimetals and strongly correlated materials." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS573/document.
Full textQuantum materials is a new term in condensed matter physics that unifies all materials in which strong electronic correlation governs physical properties of the system (e.g. Mott insulators) and materials whose electronic properties are determined by the geometry of the electronic wave function (e.g. Dirac materials). These materials show emergent properties– that is, properties that only appear by intricate interactions among many degrees of freedom, such as charge, spin and orbital, giving rise to topological properties of electrons. The study of these interactions and competitions between the relevant degrees of freedom demands applying ultrafast pump-probe techniques. Particularly, femtosecond laser pulses act only on the electrons and set them to an out-of-equilibrium state inexplicable by the Fermi-Dirac distribution. The ensuing dynamics involves various processes and the rate at which the relaxation occurs is related to the coupling constants. Moreover, in time-resolved pump-probe techniques light can act as an additional external parameter to change of the phase diagram – different from thermodynamic parameters. It gives us the opportunity of stabilizing new states inaccessible by quasi-adiabatic thermal pathways or eventually manipulating the physical properties of the systems.In this thesis, we performed different experiments in order to study the equilibrium and out-of-equilibrium properties of two correlated compounds: BaCo₁₋ₓNiₓS₂ and (V₁₋ₓMₓ)₂O₃.The first part of the project was mainly devoted to the study of BaNiS₂ that is the metallic precursor of the Mott transition in BaCo₁₋ₓNiₓS₂. By applying ARPES, we studied the electronic band structure of BaNiS₂ in its entire Brillouin zone. These results combined with some theoretical calculations give evidence of a novel correlation-induced and two-dimensional Dirac cone with d-orbital character. The band crossing is protected by the specific symmetries of the crystal structure. We also investigated the electronic band structure of the Mott insulator BaCoS₂ in its magnetic and nonmagnetic phases.In the second part, we studied the out-of-equilibrium electron dynamics of BaNiS₂ and (V₁₋ₓMx)₂O₃. By means of tr-ARPES and tr-reflectivity measurements, we observed an ultrafast and non-thermal renormalization of the Dirac cone in BaNiS₂ . This phenomenon is purely provoked by the electronic excitation and is stabilized by the interplay between the electrons and phonons. Moreover, by applying various pump-probe techniques (XFEL-based tr-XRD and tr-Reflectivity) we also explored the out-of-equilibrium phases of the prototype Mott-Hubbard material (V₁₋ₓMx)₂O₃ in different parts of its phase diagram. Our results show a transient non-thermal phase developing immediately after ultrafast photoexcitation and lasting few picoseconds in both metallic and insulating phases. This transient phase is followed by a structural distortion that corresponds to a lattice hardening and is marked by a “blue shift” of the A₁g phonon mode. These results underline the importance of the orbital filling as well as the strong effect of the selective electron-lattice coupling in the strongly correlated materials