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1
Friedrich, J. O. "Frequency and spatial selectivity in nuclear magnetic resonance spectroscopy." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234964.
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Omnes, Laurent. "Towards the biaxial nematic phase via specific intermolecular interactions." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368368.
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Schmid, Jean-Claude. "Marqueurs biologiques soufres dans les petroles." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13146.
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Identification et geochimie des marqueurs biologiques soufres dans deux petroles particulierement riches en soufre: petroles de marvejols, bassin d'alis france et de rozel point, utch, etats-unis. La diversite des composes organo-soufres et leur teneur dans les petroles indiquent que la formation de ces molecules se fait tres probablement par un processus non-biologique. L'incorporation de soufre dans la matiere organique sedimentaire se ferait principalement a un stade precoce de la maturation sur des molecules fonctionnalisees, notamment des alcenes
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Peiponen, K. E. (Kai-Erik). "Optical spectra analysis of turbid liquids." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514291685.
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This thesis is devoted to methods of analyzing optical spectra obtained from turbid liquids, i.e., liquids that are optically very thick and/or scatter light. Data for spectral analysis were obtained with a new, multifunction spectrophotometer developed for industrial liquid samples. One characteristic of the spectrophotometer is that spectral analysis methods can be implemented into the software. Here, the emphasis was on data inversion methods, particularly the Kramers-Kronig analysis and the maximum entropy method, which can be used to gain information on the wavelength-dependent complex refractive index of liquid samples. Relating to such characteristics as density and colour, the complex refractive index also helps to identify the species that form a liquid. The methods were applied to study the internal reflection of light from the prism-liquid interface of the probe and to analyze surface plasmon resonance spectra. This study provided new methods of investigating the optical properties of relatively difficult objects, like offset inks, and of assessing adhesion forces between ink and the substrate system. Another important part of the thesis was the exploration of spectral analysis methods to obtain optical properties of nanoparticles in a liquid matrix. Bounds for the optical properties of multi-component structures in a liquid were considered with the aid of Wiener bounds.
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Bernhem, Kristoffer. "How ionic are ionic liquids?" Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41033.
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Ionic liquids are continuously finding more and more applications, both in research and in the industry. Many attempts have been made to find parameters that could be used to describe all ionic liquid systems. Five years ago a Japanese group applied the work of Gutmann on ionic liquids to use ionic association to describe solvation effects. The group calculated ionic association from conductivity and diffusion measurements. This report presents a direct approach through electrophoretic NMR to measure ionic association in ionic liquids. The report contains a brief introduction to ionic liquids and their properties as well as a short explanation of Nuclear Magnetic Resonance (NMR) spectroscopy, diffusion NMR and a more detailed explanation of electrophoretic NMR (eNMR). Experimental setups, taken from previous work by the NMR group at Physical Chemistry KTH, have been modified to allow for measurements in ionic liquid systems. The report discusses the issues that can arise when measuring eNMR in ionic liquids and suggests solutions. The method developed is principally built upon experiments on 1-butyl-3-methyl-imidazolium trifluoroacetate and is directly applicable to other ionic liquid systems. For more viscous systems than the one investigated here, slight changes will need to be made, as explained in the report. In order to evaluate the method developed during the project the degree of association for 1-butyl-3-methyl-imidazolium trifluoroacetate has been calculated from experimental results and results in similar values as reported by Tokuda et al.. Furthermore, the temperature variation due to Joule heating during a complete eNMR experiment was also investigated by observing change in chemical shift.
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Giraud, Gerard. "Ultrafast vibrational dynamics in liquids and proteins." Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275153.
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Radhi, Asanah. "NMR studies of cellulose dissolution in ionic liquids." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7844/.
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This study examines the properties of ionic liquid and co-solvent mixtures, investigating fundamental aspect of cellulose dissolution in ionic liquids and developes a new technique to study the kinetics of cellulose coagulation. The first system that we studied is the mixture of 1-Ethyl-3-Methylimidazolium Acetate (EMIMAc) and Dimethyl Sulfoxide (DMSO). The motivation behind this study is that the use of DMSO as a co-solvent for cellulose dissolution in ionic liquid makes the cellulose processing more efficient and cost effective. Detailed studies of solutions are carried out to probe the macro- and micro-scopic changes of the ionic liquid properties as well as DMSO in the mixtures. The results suggest that ionic liquid and DMSO mixtures behave almost like an ideal solution. Solutions of 1-Butyl-3-Methylimidazolium Chloride (BMIMCl)-cellulose are investigated across a range of cellulose concentrations and temperatures using NMR- spectroscopy and relaxometry, diffusion and viscosity measurements. Using Bloemberg-Purcell-Pound (BPP) theory, NMR relaxation times T1 and T2 have been expressed in terms of an isotropic correlation time, τc for molecular motion. The derivation of the relation between correlation time and translational diffusion shows that the rotational motion can be best correlated to translational motion in term of hydrodynamic radius and activation energy. Mixtures of ionic liquids and carbohydrates (glucose, cellobiose and cellobiose) are investigated using viscosity and NMR spectroscopy, relaxometry and diffusion measurements. The results give the interaction stoichiometry of ionic liquid:hydroxyl group, 1:1. Analysis of the dynamic properties of the mixtures suggests that in solutions the bulk viscosity, η is best replaced by a microviscosity, ηµ = fµη, where fµ is the microviscosity correction factor. A new method to study the kinetics of cellulose coagulation in water from cellulose/IL/co-solvent using NMR has been successfully developed. Diffusion coefficients of EMIMAc and DMSO are found not to be significantly affected by cellulose and DMSO concentrations within the range studied, which suggests that if we want to change the coagulation rate and therefore the morphology, we would need to change the anti-solvent.
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Medford, Hannah T. Macdonald Jeffrey. "Colon cancer diagnosis using NMR spectra of urine." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,284.
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Thesis (M.S.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Biomedical Engineering." Discipline: Biomedical Engineering; Department/School: Medicine.
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Palfreyman, Stuart A. "Sonically induced narrowing of the NMR spectra of solids and other novel NMR techniques." Thesis, Aston University, 1996. http://publications.aston.ac.uk/9610/.
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A typical liquid state NMR spectrum is composed of a number of discrete absorptions which can be readily interpreted to yield detailed information about the chemical environment of the nuclei found within the sample. The same cannot be said about the spectra of solid samples. For these the absorptions are typically broad, featureless and yield little information directly. This situation may be further exacerbated by the characteristically long T1 values of nuclei bound within a solid lattice which, consequently, require long inter-sequence delays that necessitate lengthy experiments. This work attempts to address both of these inherent problems. Classically, the resolution of the broad-line spectra of solids into discrete resonances has been achieved by imparting to the sample coherent rotation about specific axes in relation to the polarising magnetic field, as implemented in the magic-angle spinning (MAS) [1], dynamic angle spinning (DAS) [2] and double rotation (DOR) [3] NMR experiments. Recently, an alternative method, sonically induced narrowing of the NMR spectra of solids (SINNMR) [4], has been reported which yields the same well resolved solid-state spectra as the classic solid-state NMR experiments, but which achieves the resolution of the broad-line spectra through the promotion of incoherent motion in a suspension of solid particles. The first part of this work examines SINNMR and, in particular, concentrates on ultrasonically induced evaluation, a phenomenon which is thought to be essential to the incoherent averaging mechanism. The second part of this work extends the principle of incoherent motion, implicit in SINNMR, to a new genre of particulate systems, air fluidized beds, and examines the feasibility of such systems to provide well resolved solid state NMR spectra. Samples of trisodium phosphate dodecahydrate and of aluminium granules are examined using the new method with partially resolved spectra being reported in the case of the latter.
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Aujla, R. S. "Carbon-13 NMR spectra of solid dyestuffs and polymers." Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304771.
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Wang, Shao-Pin. "Raman studies of reorientational dynamics in liquids." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc332457/.
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Raman and/or infrared (IR) bandshape analysis to probe molecular dynamics in liquids has become a rapidly expanding field of study in recent years. Determination of spinning and tumbling diffusion constants, Dι and D⊥, which characterize the reorientation of symmetric-top moleclues has been successfully studied in a number of D6H and D3H molecules. For molecules of CV3 symmetry, however, previous attempts to extract spinning diffusion constants from Raman doubly degenerate vibrations (E mode) have proved unsuccessful. Presented here is a new methodology which resolves the problems encountered by former researchers through calculation of Dι utilizing the narrower Lorentzian component of E vibrations.
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Allen, Stephen George. "The characterisation of pore morphology by NMR." Thesis, University of Kent, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267501.
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Readshaw, S. A. "The conformational analysis of cyclic molecules by NMR spectroscopy." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378941.
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Rodriguez, Arturo A. (Arturo Angel). "Raman and NMR Relaxation Studies of Molecular Dynamics in Liquids." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc330818/.
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Raman vibrational bands are sensitive to fluctuations in the molecular environment. Variations in the bandwidth and peak position can then be utilized to monitor molecular forces and interactions present in condense phases.
Nuclear Magnetic Resonance (NMR) provides a convenient probe for the study of molecular reorientation in liquids since nuclear spin relaxation times are dependent on the details of molecular motion.
Presented here is the solvent study of the Raman bandwidths and frequency displacements of the mode of the compounds CH3MCI3 (M = C, Si, Ge, Sn) in a number of solvents of widely varying molecular structure. Also, a detailed isotope dilution study of the modes in CH2CI2/CD2CI2 mixtures is presented. In this set of experiments, I observed broadening of the v1 mode of CH2C12 upon dilution,which is the first experimental observation of such behavior.
The temperature-dependent carbon-13 relaxation times and nuclear Overhauser enhancements in neat dichloromethane were measured. In this study we found that the molecular reorientation of this molecule was highly anisotropic, but could be well characterized assuming quasi-symmetric top behavior. In addition, in order to gain a more complete understanding of the reorientational dynamics in dichloromethane, we analyzed the 13-C NMR relaxation of CH2CI2 both in "inert" solvents of differing viscosities and in interactive solvents of varying Lewis basicities. Various theoretical models were also applied in order to characterize dichloromethane1s reorientational dynamics.
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Doyle, Victoria Louise. "Quantification of localised in vivo magnetic resonance spectra." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268054.
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Howarth, M. A. "Methods for the interpretation of proton NMR spectra of proteins." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376918.
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Veselkov, Kirill. "Computational approaches to improve information recovery from biological NMR spectra." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502905.
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Adams, Krysten Scott. "Using computational methods to predict NMR spectra for polyether compounds /." Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/adamsk/krystenadams.pdf.
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Ailey, Bartlet Gilbert. "The assignment of protein NMR spectra using a genetic algorithm." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/29635.
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NMR spectroscopy is one of the two methods for determining the structures of proteins. The production of a structure using NMR has a number of phases; with the assignment phase being one of the most time consuming. Any automation, even partial, of the assignment process would be of enormous benefit. This thesis describes five modules (2D-SAM, 3D-SAM, BAM-1, BAM-2 and SCAM) that use a genetic algorithm (GA) to assign protein NMR spectra. The 2D-SAM and 3D-SAM are Sequential Assignment Modules. They take the relevant spin system identification and sequentially assign either 2 dimensional homonuclear or 3 dimensional heteronuclear NOESY spectra. The 2D-SAM is effective with small proteins which generate high quality spectra while the 3D-SAM is effective with larger isotopically labelled proteins. The BAM-1 and BAM-2 are Backbone Assignment Modules. The BAM-1 takes several triple resonance spectra and assigns the peaks to relevant nuclei creating peak systems. The BAM-2 takes the peak systems and sequentially assigns them. The SCAM is a prototype Side Chain Assignment Module; it is designed to take either a HCCH C13 TOCSY or COSY spectrum and assign its peaks to certain types of amino acid. The BAM-1, BAM-2, and SCAM were designed to work in sequence to assign a whole protein. Although each module is designed to assign a specific type of spectrum or spectra they are all based around the same GA core. This core uses a crowding factor, phenotypic domain specific genetic operators and a novel age concept to improve its performance. When evaluated the performance of each module (average correct assignment) was 2D-SAM 100%, 3D-SAM 71%, BAM-1 96% and BAM-2 75%.
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Portieri, Alessia. "Solid state NMR of sulfa-drugs." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3781/.
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This work has been a study of systems, mostly of sulfa-drugs, showing polymorphic behaviour. Using different means as solid state NMR, X-ray analysis, and theoretical calculations, we have seen how it is possible to understand results obtained from the different techniques, proving how the study of polymorphic systems needs cooperative advice from the different techniques that are able to detect polymorphic differences. Within the sulfa-drugs I have been mostly concentrating on sulfanilamide, studying (^13)C and (^15)N solid state NMR spectra of the different polymorphs. The NMR parameters that have been most interesting to study, have been the relaxation times that have revealed complicated motion of the molecule despite it being a small molecule. In order to obtain detailed information from (^15)N spectra it has been necessary to enrich the samples and this has enabled a study of the shielding tensors of the nitrogens in the molecule. (^13)C spectra were also recorded of systems studied sulfathiazole solvates that proved to show some of the same solid state effects in the NMR spectra as sulfanilamide. Shielding calculations have proved to be still limited in order to obtain reliable information on the shielding of both and (^13)C (^15)N nuclei but considering hydrogen-bonded molecules, as opposed to isolated molecules, seemed to have improved the calculations quite a lot, so that some idea of intermolecular effects could be deducted. Exact positions of the hydrogen has proved to be essential as well in order to improve the calculations. Finally a case study for the REDOR pulse sequence has been carried out. Different attempts to understand the effects influencing this particular experiment have been carried out on 20% and 99% doubly enriched glycine, as well as on a particular sample, doubly enriched BRL55834, but the internuclear distances measured with this technique still displayed some uncertainties that made results not thoroughly reliable.
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Benmansour, Hadjar. "Palladium catalysed reactions of halogenated heterocycles." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/4948/.
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1- The synthesis of unusually substituted halo-fluoroheterocycles has been achieved. 2,4,6-Tribromo-3,5-difluoropyridine and 4-bromo-2,3,5,6-tetrafluoropyridine were prepared from pentafluoropyridine, aluminium bromide and hydrogen bromide Reactions with lithium halides allowed the preparation of 4-iodo-2,3,5,6- tetrafluoropyridine, 4-iodo-2,6-dibromo-3,5-difluoropyridine, 4-iodo-2,3,5,6- tetrafluoropyridine and 4-chloro-2,6-dibromo-3,5-difluoropyridine.2- Reactions of 2,4,6-tribromo-3, 5-difluoropyridine with nucleophiles showed that selective substitution at the C-F centre can be achieved using hard (sodium ethoxide, phenoxide) nucleophiles.3- Lithium mediated reactions of 2,4,6-tribromo-3,5-difluoropyridine allowed selective functionalisation of the 4-position; lithium-halogen exchange occurred exclusively at this position giving a stable lithium derivative, which was successfully trapped with a range of electrophiles (trimethylsilyl chloride, acid chlorides).4- Palladium mediated couplings of 2,4,6-tribromo-3,5-difluoropyridine with a range of substituted phenylacetylenes was successful and the 2- and 6-positions were the most activated sites. Coupling with boronic acids gave the disubstituted or trisubstituted products; in the case of trisubstitution, all three positions (2-,4- and 6-) were activated towards coupling. 2,4,6-Tribromo-3,5-difluoropyridine formed a stable zinc derivative, which was coupled with iodoaromatics (iodobenzene, diiodobenzene).
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Digby, Megan Elizabeth. "Broadband DC SQUID NMR spectrometry on metals." Thesis, Royal Holloway, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322702.
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This Thesis describes the development of a broadband pulsed NMR spectrometer, based on a sensitive DC SQUID amplifier with wideband electronics, to observe directly the free precession of nuclear spins in bulk metallic samples (with broad NMR linewidths) at Larmor frequencies cß/2 ,r below 1 MHz. The sample is located inside a pickup coil, which forms a superconducting flux transformer with the input coil of the SQUID. The SQUID amplifier operates in a flux-locked-loop (FLL), hence it is sensitive to signals from DC up to the bandwidth of the FLL electronics. A modified commercial DC SQUID amplifier, with modulated feedback electronics, observed NMR signals from bulk platinum samples (T2 - 1.1 ms), at 1.5 K. The SQUID amplifier had a 50 kHz bandwidth, a dead-time - 50 μs, and a coupled energy sensitivity cc - 500h. The measurements showed that it is important to minimise the time-constant of eddy current decay in the sample, which scales with r2, as expected, where r is the sample dimension. A DC SQUID amplifier with additional positive feedback and wideband electronics configured using the direct offset integration technique, observed NMR signals from a bulk aluminium sample (T2 - 30 μs) at 20 mK. This SQUID amplifier had a 7.5 MHz bandwidth, the dead-time was 55 μs for small transmitter pulses and e,; - 600h. The use of a strongly coupled input coil with the SQUID necessitated damping across the coil to smooth out the SQUID flux-voltage characteristicThe NMR measurements showed that eddy current decay is less important if the NMR signal size is enhanced by cooling the sample. Measurements also confirmed that the NMR signal from bulk metal is proportional to 4c0, and that a reasonable estimate of the signal size is made by assuming the signal is due to spins within half the skin-depth of the surface
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Wang, Kuen-Shian. "FT-NMR and Raman Spectroscopic Studies of Molecular Dynamics in Liquids." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc277788/.
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NMR relaxation and Raman lineshape analysis are well known methods for the study of molecular reorientational dynamics in liquids. The combination of these two methods provides another approach to tackle the characterization of molecular dynamics in liquids. Investigations presented here include (1) NMR relaxation study of polycyclic compounds in solution, (2) the study of nitromethane reorientational dynamics using the NMR and Raman methods, and (3) Raman lineshape analysis of reorientation hexafluorobenzene/benzene mixtures.
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Romanova, Ekaterina, Bärbel C. Krause, Alexander Stepanov, Baten Jasper M. van, Rajamani Krishna, Jörg Kärger, and Dieter Freude. "1 H NMR signal broadening in spectra of MFI type zeolites." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194086.
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Huang, Yuanyuan. "Effects of molecular motion on deuteron magic angle spinning NMR spectra." W&M ScholarWorks, 2007. https://scholarworks.wm.edu/etd/1539623519.
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Solid state deuteron NMR experiments, especially magic angle spinning (MAS) and off-magic angle spinning (OMAS), are developed to explore dynamical systems. A theoretical discussion of interactions relevant for spin-1 nuclei is presented. Practical aspects of MAS/OMAS experiments are described an detail. The dominant quadrupolar coupling interaction in deuteron NMR has been simulated and the effects of multiple-frame molecular motions on MAS/OMAS spectra are taken into account in this calculation. Effects of chemical shift anisotropy are also simulated, and shown to be small under conditions of rapid sample spinning.;Two numerical methods, direct integration and an efficient simulation routine based on Floquet thoery, are discussed. Improvements in computational efficiency of the Floquet method in computing solid stae deuteron MAS/OMAS spectrum makes the quantitative analysis of molecular motion possible: complex multiple frame molecular motions, deuteron quadrupolar interactions and chemical shift anisotropy are now included in a single simulation routine and the effects of the multiple-frame molecular motions can be analyzed by comparing the line shapes of simulations with those of experiments.;The enhanced motional sensitivity of deuteron NMR MAS/OMAS makes it possible to detect temperature-dependent motion rates of urea molecules in octanoic acid/urea inclusion compounds. Temperature-dependent deuteron OMAS line shapes have been recorded and fitted through least-square procedures, to provide rates of rotation about both CN and CO bonds. Activation energies have been calculated for these motions. The power and utility of OMAS is demonstrated by this investigation.;The phenyl ring motions in appropriately labeled L-phenylalanine and N-acetyl-L-phenylalanine methyl ester/cyclodextrin inclusion compound have also been studied through high field deuteron MAS experiments. Phenylalanine MAS spectra with ultra-fast ring-flip motion have been simulated and the range of phenyl ring flip rates is obtained by comparing the simulated and experimental spectra. In the studies of phenylalanine/cyclodextrin inclusion compound, an approach to a physically reasonable diffusion model has also been made by increasing the number of jump sites per unit solid angle included in the calculation. These simulations involve repeated diagonalization of very large matrices and demonstrate the capability of the approach to handle complex dynamical systems.
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Bruce, Stephen Derek. "Accurate quantification of the proton NMR spectra of human brain metabolites." Thesis, Edinburgh Napier University, 2002. http://researchrepository.napier.ac.uk/Output/5731.
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Magnetic Resonance Spectroscopy (MRS) can give chemically specific information about biological tissue and has become an active area of research in human metabolism in health and disease. In particular, the (1)H MKS modality is suited to studies of the brain, and the commonly studied metabolites that have important biochemical roles are choline, creative and N-acetyl aspartate (NAA). The success of MRS as a medical diagnostic tool depends heavily on accurate quantification of the data by computer analysis, in order to determine frequencies for the identification of metabolites and peak areas to obtain metabolite concentrations. MRS performed on standard clinical scanners has problems regarding the homogeneity of the magnetic field across the region being measured and this results in a broadening of the inherently Lorentzian peaks of metabolite resonances. T'he broadening effect can be approximated by a Gaussian function and so observed peaks are of a Voigt form. However, traditional computer modeling of MRS data usually assumes a purely Lorentzian model. Although the Voigt function is theoretically the most appropriate model for quantification, its complex form presents an unnecessary time burden when analyzing multiple spectra. An accurate approximation to the Voigt function, consisting of a linear summation of Lorentzian and Gaussian functions, is given in this work. The maximum error in determining peak areas using the approximation is shown to be 0.72% over the entire range of simulated Voigt line shapes. Furthermore, it is shown that the approximation can be derived analytically from the actual Voigt function in the regions where the Lorentzian or Gaussian components are dominant. The (1)H spectra of dilute solutions containing choline, creative and sodium acetate were collected from an Elscint Prestige 1.9T and a GE Sigma EchoSpeed 1.ST clinical scanner and quantified by fitting with model line shapes using a Levenberg-Marquardt non-linear least squares routine. Compared with an approximated Voigt model, fitting with purely Gaussian and Lorentzian models resulted in a increase of (% mean ± SE) that was as much as 19.06 ± 0.39 and 405.48 ± 5.66 respectively. Similar trends were observed from fitting two in vivo spectra of a healthy volunteer, where using purely Gaussian and Lorentzian models resulted in a % increase of that was around 3% and 20% respectively. The relaxation times T(1) and T(2) of choline, creative and sodium acetate were estimated from measurements performed on the two clinical scanners and compared with estunates from similar measurements performed on a high resolution spectrometer. After correcting spectra for relaxation effects, the choline/creative and the choline/sodium acetate peak area ratios (mean ± SE) were 3.01 ± 0.02 and 3.03 ± 0.03 respectively on the GE scanner compared to an ideal value of 3. Use of an inappropriate line shape model leads to systematic errors not only in peak areas, but also area ratios of overlapping spectral peaks. Compared to fitting with the approximated Voigt model, noticeable discrepancies in the choline/creative area ratio was observed when fitting with the Gaussian model (3.7%) and the Lorentzian model (15.7%). Similarly for the in vivo spectra, a noticeable discrepancy in the NAA/creatine area ratio was observed when fitting with the Gaussian model (4.8%) and the Lorentzian model (12.6%). Therefore the approximated Voigt model returned more accurate fits and should be considered as the standard line shape in the reporting of spectroscopic studies of human brain metabolites. A small scale reproducibility study was performed on the two clinical scanners to determined the precision to which metabolite peak areas could be measured, and greater precision was observed on the GE scanner. The coefficient of variation (CV) of the `within-run' reproducibility (no repositioning of solutions between measurements) was within 3.7% for spectra of dilute solutions and 7.8% for in vivo spectra. The `within session' reproducibility (repositioning of sample between measurements) was within 0.9% for spectra of dilute solutions. The `between-days' reproducibility for spectra of dilute solutions, quantified by a t-test, showed no significant differences between both the mean peak areas for any of the metabolites or the choline/creative and the choline/sodium acetate peak area ratios (p > 0.05 in all cases).
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Romanova, Ekaterina, Bärbel C. Krause, Alexander Stepanov, Baten Jasper M. van, Rajamani Krishna, Jörg Kärger, and Dieter Freude. "1 H NMR signal broadening in spectra of MFI type zeolites." Diffusion fundamentals 6 (2007) 68, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14248.
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Li, Lilong Wu Yue. "Dynamics and structure in metallic supercooled liquids and glasses studied by NMR." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2005. http://dc.lib.unc.edu/u?/etd,335.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Curriculum in Applied and Materials Sciences." Discipline: Applied and Materials Sciences; Department/School: Applied and Materials Sciences.
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Yuan, Peng. "Raman and NMR Investigation of Molecular Reorientation and Internal Rotation in Liquids." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc278558/.
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Molecular rotational motions are known to influence both Raman scattering of light and nuclear spin relaxation. Therefore, the application of Raman bandshape analysis and NMR relaxation time measurements to probe molecular dynamics in liquids will provide us with a deeper understanding of the dynamical behavior and structure of molecules in the liquid phase. Presented here are (i) studies of molecular reorientation of acetonitrile in the neat liquid phase and in solution by Raman bandshape analysis and NMR relaxation; (ii) studies of reorientational dynamics and internal rotation in transition metal clusters by NMR relaxation.
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Chen, Jen Hui. "Molecular Dynamics and Interactions in Liquids." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc331452/.
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Various modern spectroscopies have been utilized with considerable success in recent years to probe the dynamics of vibrational and reorientational relaxation of molecules in condensed phases. We have studied the temperature dependence of the polarized and depolarized Raman spectra of various modes in the following dihalomethanes: dibromomethane, dichloromethane, dichloromethane-d2, and bromochloromethane. Among other observed trends, we have found the following: Vibrational dephasing times calculated from the bend) and (C-Br stretch) lineshapes are of the same magnitude in CI^B^. The vibrational dephasing time of [C-D(H) stretch] is twice as long in CD2Cl2 as in CH-^C^, and the relaxation time of (C-Cl stretch) is greater in CI^C^ than in CD2CI2. Isotropic relaxation times for all three stretching vibrations are significantly shorter in C^BrCl than in CI^C^ or CI^B^. Application of the Kubo model revealed that derived modulation times are close to equal for equivalent vibrations in the various dihalomethanes. Thus, the more efficient relaxation of the A^ modes in CE^BrCl can be attributed almost entirely to the broader mean squared frequency perturbation of the vibrations in this molecule.
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Robertson, James P. "Automated strategies for the assignment of the NMR spectra of homologous proteins." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357599.
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Hughes, Colan Evan. "New techniques in NMR spectroscopy." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297524.
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Chakraborty, Saswata. "Mechanistic Study of Photo-bis-Decarbonylation of Alpha-Diketones." Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1277056870.
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Juenemann, Jessica C. "UV-VIS and NMR spectroscopic studies of a palladium macroscopic square complex." Virtual Press, 2003. http://liblink.bsu.edu/uhtbin/catkey/1273267.
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Skrynnikov, Nikolai R. "Effects of multispin modes in intermolecular NMR relaxation and chemical exchange in liquids." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34458.
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While effects of multispin modes have proven to be of utmost importance in Nuclear Magnetic Resonance spectroscopy, their roles in two intimately related fields--chemical exchange and intermolecular spin relaxation--have not been adequately explored. In a bid to improve theoretical understanding, this work presents the generalized symmetry-adapted form of the exchange superoperator, which allows for proof of the macroscopic symmetry principle. The results obtained for an $A sb2$-AB type exchange are used to explain the presence of paradoxical symmetry-forbidden signals in the spectra of parahydrogen labeled symmetric substrates such as acetylenedicarboxylic acid dimethyl ester. The implementation of the chemical exchange for the magnetic resonance simulation platform GAMMA is reported. The simulations of the novel experiment aimed at the detection of the slow intermolecular exchange through the decay of the multispin modes are presented. The exchange model is also employed to elucidate the role of intermolecular spin coherences in liquid phase. In the second part of this work, the derivation of the Redfield equations adapted for spin evolution under the time-dependent Hamiltonian is presented. The results are used to discuss the limitations of the Redfield theory as applied to relaxation measurements in the rotating frame. Rigorous spin-algebraic analysis makes it possible to establish the selection rules for the intermolecular relaxation thus clarifying the scope and the structure of relaxation coupling for the multicomponent solutions. Obtained results suggest the formulation of a Coupled Solute-Solvent Relaxation model, more compact than the complete system of Redfield equations, yet more precise than the External Random Field approach. The exact expressions for the intermolecular relaxation in AX-AB and AX-ABX type mixtures are derived and subsequently used to confirm the excellent precision of the Coupled Solute-Solvent approximation, distinctly superior to
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Skrynnikov, Nikolai R. "Effects of multispin modes in intermolecular NMR relaxation and chemical exchange in liquids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0013/NQ30389.pdf.
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Harvey, Pierre Dominique. "Applications of vibrational spectroscopy and NMR spin-lattice relaxation time measurements to organometallic and organic molecular crystals." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=73986.
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Knight, Cheryl Lynn. "Application of IR and NMR spectroscopy to certain complexes of 8-hydroxyquinoline and 8-aminoquinoline." Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/22001.
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The IR spectra of twenty-one transition metal complexes of 8-hydroxyquinoline over the range 700 - 50 cm⁻¹ are discussed in relation to their known or inferred structures. The complexes are of three types: (a) the bis(aquo) complexes of the first row transition metal(II) ions, [M(ox)₂(H₂O)₂] (M =Mn, Fe, Co, Ni, Cu, Zn); (b) the corresponding anhydrous complexes, [M(ox)₂]n (M=Mn, Co, Ni, Cu, Zn) and (c) the complexes of the metal(III) ions, [M(ox)₃] (M = Sc, V, Cr, Mn, Fe, Co, Ga, Rh and In). Deuterated 8-hydroxyquinoline was. synthesized by the Skraup synthesis and has been used to assist in the assignment of the metal-ligand modes. The assignment of these bands was further based on ⁶⁴,⁶⁸Zn labellihg of the bis(aquo) zinc chelate and on the effects of metal ion substitution in relation to structural considerations based on crystal field theory. An investigation of the IR spectra of a series of -tris, bis and mono(8-aminoquinoline) complexes of the first transition row metal(II) perchlorates and halides is reported.
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Conroy, Matthew James. "NMR studies of bacterial light-harvesting complexes." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298888.
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Dutta, Sujeet. "Adsorption and imbibition of binary liquids in nanoporous solids." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S129/document.
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Les mélanges de toluène et de tert-butanol sont complètement miscibles dans toutes les compositions à l'échelle macroscopique. Toutefois tert-butanol forme un réseau de liaisons hydrogène à l'échelle nanométrique qui persistent même dans les mélanges liquides binaires tert-butanol/toluène. Des expériences de diffusion de neutrons ont révélé la séparation des phases du mélange dans une structure cœur-gaine sous confinement dans des solides nanoporeux hydrophiles. Le travail effectué dans cette thèse vise à comprendre le rôle joué par la concurrence des interactions intermoléculaires (liaisons hydrogène, Van der Waals) lors de la séparation de phase sous nanoconfinement. Des expériences de RMN révèlent la persistance d'un réseau de liaisons hydrogène dans ces liquides binaires confinés dans des nanopores de silice à des concentrations faibles de tert -butanol, fournissant la preuves d'un autre type de réseau de liaisons hydrogène sous confinement. Des expériences d'adsorption du mélange gazeux dans des nanopores de silice ont aidé à expliquer l'affinité plus élevée des parois de silice polaires pour tert-butanol par une modèle thermodynamique. Le remplacement de la matrice hôte par un analogue hydrophobe est associé à une inversion de la sélectivité, montrant cette fois une plus grande affinité du toluène pour la surface des pores. L'effet des interactions spécifiques avec la surface sur la dynamique d'imbibition spontanée de ces liquides binaires à travers le réseau de silice nanoporeux a également été étudié. Des expériences de radiographie de neutrons ont révélé la séparation des flux à deux composants, au sein d'une dynamique toujours gouvernée par une loi de Lucas-WashburnToluene and tert-butanol mixtures are completely miscible for all compositions at the macroscopic scale. However tert-butanol forms a network of hydrogen-bonded clusters at the nanoscale which persist even in the tert-butanol-toluene binary liquid mixtures. Interpretation of neutron scattering experiments revealed phase separation of the mixture into a core-shell structure inside hydrophilic nanoporous solids, with a tert-butanol shell and a toluene core. The work carried out in this thesis is aimed at understanding the role played by competing intermolecular interactions (hydrogen-bonding, van der Waals) in driving phase separation in confinement. NMR experiments reveal the persistence of a hydrogen-bonding network in these binary liquids confined in silica nanopores even at very low concentrations of tert-butanol, providing evidence of a new kind of hydrogen bonded network under confinement. Vapour sorption isotherms of tert-butanol-toluene binary gas mixtures in silica nanopores helped explain higher affinity of polar silica walls for tert-butanol by a thermodynamic model. Replacing the host matrix by a hydrophobic analogue was found to reverse the selectivity, with toluene showing greater affinity for the pore surface. Effect of surface specific interactions was studied on spontaneous imbibition dynamics of these binary liquids through nanoporous silica network. Neutron radiography experiments revealed the separation of fluxes into a twocomponent flow, generally obeying the Lucas-Washburn law
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Heindrichs, Axel Stefan Dirk. "New methodologies in solid state NMR." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342111.
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Michez, Roman. "Contribution to the Electroreduction of CO2 in Ionic Liquids." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/268218.
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Afin de s’affranchir de contraintes liées à l’utilisation de milieux conventionnels, l’électroreduction du CO2 a été étudiée en milieux liquides ioniques. L’activité de l’interface électrode - électrolyte a été examinée par techniques électrochimiques et les produits de réactions formés après électrolyses sous contrôle potentiostatique, ont été analysés par techniques chromatographiques et spectroscopie RMN. L’ensemble des informations obtenu lors de ces analyses a permis de contribuer à une meilleure compréhension des mécanismes réactionnels de l’électroréduction du CO2 en milieux liquides ioniques. Au travers de ce travail, l’influence de la composition du liquide ionique sur l’électroréduction du CO2 conduite à une électrode d’or a pu être étudiée, en recourant à des liquides ioniques constitués de différents cations (imidazolium, pyrrolidinium, pipéridinium et tétraalkylammonium) et du même anion [NTf2]-. En milieu [BMIm][NTf2], la présence du proton acide H-2 du cation [BMIm]+ favorise la formation de CO, principal produit formé à l’électrode d’or polycristallin. Cependant, la réduction du cation [BMIm]+ apparaît comme une réaction compétitive, produisant non seulement du carbène, mais également des dimères hydrogénés et un monomère. La différence de sélectivité de ces produits observée à différents matériaux d’électrode a pu être interprétée sur base des capacités différentes des surfaces métalliques à adsorber l’hydrogène. En présence de ces produits générés électrochimiquement, le CO2 est indirectement converti produisant en partie un adduit. Dû fait de la faible chargée transféree durant électrolyse en milieu [N1,1,1,3][NTf2] et des grandes surtensions nécessaires à la réduction du CO2 en milieu [PMPip][NTf2], l’électroréduction du CO2 a été poursuivie en détail en milieu [BMPyrr][NTf2].En milieu [BMPyrr][NTf2], la réduction du cation n’apparaît plus comme une réaction compétitive, et CO peut être formé sélectivement avec d’excellentes efficacités faradiques, sans consommation des protons du liquide ionique. Dans ce milieu, la formation de CO est seulement inhibée à des potentiels plus négatifs par la formation d’oxalate, la dégradation de l’anion [NTf2]- et par la corrosion cathodique de l’électrode d’or. De plus, le présent travail a montré que la sélectivité pour la formation de CO et d’oxalate est affectée par la nature du matériau d’électrode, grâce à l’utilisation d’une surface de cuivre. A une électrode de cuivre polycristallin, la présence d’une source de proton, telle que H[NTf2], permet également la formation de produits à haute valeur ajoutée, telle que le méthane ou l’acide formique.A une électrode d’or polycristallin, la formation d’adduits en présence de CO2 n’a pas seulement été observée en milieu [BMIm][NTf2], mais également après ajout d’un co-réactant, telle que des bipyridines, en milieu [BMPyrr][NTf2]. Le mécanisme de réaction diffère cependant selon la structure de la bipyridine.To avoid limitations encountered in conventional media, the electroreduction of CO2 has been studied in ionic liquids. The activity of the ionic liquid - electrode interface was examined by electrochemical techniques and the reaction products were analysed after controlled-potential electrolysis, by chromatographic techniques and NMR spectroscopy. The information obtained by these analysis have contributed to a better understanding of the reaction pathways of the electroreduction of CO2 in ionic liquids media. In this work, the influence of the ionic liquid composition on the electroreduction of CO2 conducted at gold electrodes was studied by resorting to ionic liquids composed of different cations ( imidazolium, pyrrolidinium, piperidinium and tetraalkylammonium) and the same anion [NTf2]−. In [BMIm][NTf2], the presence of acidic H-2 proton on the [BMIm]+ cation favours the formation of CO, main product formed at Au (poly). However, the reduction of the [BMIm]+ cation appears as a competitive reaction, producing not only carbene, but also hydrogenated dimers and a monomer. The selectivity of these electrogenerated products observed at various electrode materials, has been interpreted taking into account the distinct H-adsorption abilities of the metallic surfaces. In the presence of these electrogenerated products, CO2 is indirectly converted into an adduct. In ammonium-based ionic liquids, the electroreduction has been investigated in detail only in [BMPyrr][NTf2], since inhibition of the charge transfer and a high overpotential for the reduction of CO2 were observed in [N1,1,1,3][NTf2] and [PMPip][NTf2], respectively.By contrast, in [BMPyrr][NTf2], presenting no reduction reaction of the cation in competition with the CO2 electroreduction at Au (poly), the formation of CO can be selectively formed with excellent faradaic efficiency and without consumption of the RTILs protons. The selectivity for the formation of CO only decreases at more negative potentials, since the formation of oxalate, the decomposition of the [NTf2]- anion and a cathodic corrosion of the gold electrode may also take place. It has been shown that the selectivity for the formation of CO and oxalate is affected by the nature of the electrode material, using a copper surface. At Cu (poly), the presence of an additional source of proton, such as H[NTf2], to [BMPyrr][NTf2] also provides the formation of methane or formic acid.At Au (poly), the formation of adducts in the presence of CO2 has not only been observed in [BMIm][NTf2], but also after the addition of co-reactant, such as bipyridines, in [BMPyrr][NTf2]. The reaction mechanism differs, however, according to the structure of bipyridine.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Webber, John Beau W. "Accessible catalyst pore volumes, for water and organic liquids, as probed by NMR cryoporometry." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179253.
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Chemical reaction speed is frequently enhanced at a surface, particularly when materials like platinum are present. It is well known that porous materials such as sol-gel silicas, controlled pore glasses, templated porous materials such as SBA-15, MCM-41, MCM-48, and
zeolites, offer large surface areas. This in turn makes them ideal for catalysing chemical reactions. Thus an important use for porous materials is as a substrate and media to promote chemical reactions. However small pores are not always easily accessed by some of the organic liquids in which these catalytic reactions ideally take place. Cryoporometric techniques offer the possibility of directly probing the fraction of a pore that is actually accessible to a probe liquid. This fractional volume has significant impact on the catalytic efficacy of a particular solvent that is used to promote a reaction in the pores. Pore size, pore geometry, pore throat, pore surface material (hydrophilic/hydrophobic) and choice of probe liquid all influence the accessible fraction. By performing an NMR cryoporometric measurement using a particular liquid of interest, it is possible to directly access this information, which is of prime importance for catalysis, and financially very significant on an industrial scale. Results are reported here for a set of liquids, some simple alkanes (dodecane, tetradecane and hexadecane) plus water and cyclohexane, accessing pores in sol-gel silicas of nominal pore diameters 60Å, 100Å, 200Å, 500 Å. The key conclusions were that for the alkanes, the dimension of chain length was not relevantto the filling fraction, however for the cyclohexane a molecular diameter of 3.8 Å fitted the data well.
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Webber, John Beau W. "Accessible catalyst pore volumes, for water and organic liquids, as probed by NMR cryoporometry." Diffusion fundamentals 22 (2014) 13, S. 1-8, 2014. https://ul.qucosa.de/id/qucosa%3A13519.
Full textAbstract:
Chemical reaction speed is frequently enhanced at a surface, particularly when materials like platinum are present. It is well known that porous materials such as sol-gel silicas, controlled pore glasses, templated porous materials such as SBA-15, MCM-41, MCM-48, and
zeolites, offer large surface areas. This in turn makes them ideal for catalysing chemical reactions. Thus an important use for porous materials is as a substrate and media to promote chemical reactions. However small pores are not always easily accessed by some of the organic liquids in which these catalytic reactions ideally take place. Cryoporometric techniques offer the possibility of directly probing the fraction of a pore that is actually accessible to a probe liquid. This fractional volume has significant impact on the catalytic efficacy of a particular solvent that is used to promote a reaction in the pores. Pore size, pore geometry, pore throat, pore surface material (hydrophilic/hydrophobic) and choice of probe liquid all influence the accessible fraction. By performing an NMR cryoporometric measurement using a particular liquid of interest, it is possible to directly access this information, which is of prime importance for catalysis, and financially very significant on an industrial scale. Results are reported here for a set of liquids, some simple alkanes (dodecane, tetradecane and hexadecane) plus water and cyclohexane, accessing pores in sol-gel silicas of nominal pore diameters 60Å, 100Å, 200Å, 500 Å. The key conclusions were that for the alkanes, the dimension of chain length was not relevantto the filling fraction, however for the cyclohexane a molecular diameter of 3.8 Å fitted the data well.
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Galius, Veniamin. "Automated assignment of amide resonances in NMR spectra of proteins with known crystal structure /." [S.l.] : [s.n.], 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18043.
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Stoyanova, Radka. "Development and application of methods for enhancing features in NMR spectra for pattern recognition." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/8269.
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Le-That, Tran-Trung. "Switchable ionic liquids for biomass treatment : Investigation of structural changes in sodium lignosulfonate by 2D-NMR spectroscopy after treatment with switchable ionic liquids." Thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-123118.
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Joshi, Manishkumar Dilipkumar. "Synthesis of New Classes of Ionic Liquids and Polymeric Ionic Liquids and their Applications in Microextraction Techniques." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372871956.
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Mehridehnavi, Alireza. "Variable selection in neural networks for the classification of tumour tissue from '1H NMR spectra." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263843.
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Gérard, Hervé. "Simulation de spectres de résonance magnétique nucléaire de cristaux liquides, polymères cristaux liquides et polymères conventionnels." Grenoble 1, 1993. http://www.theses.fr/1993GRE10144.
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Le but de cette etude est la simulation et l'exploitation de spectres de rmn de cristaux liquides nematiques et de polymeres. Les formes de raie rmn sont analysees grace a deux modeles complementaires, le premier (modele a conformation unique) decrivant la contribution purement moleculaire (geometrie et mouvements internes a la molecule), le second la contribution des mouvements collectifs (modes visco-elastiques). Des rappels sur la methode rmn et la notion d'ordre orientationnel au sein de la phase nematique sont fournis dans la premiere partie ou sont egalement decrits ces deux modeles. Dans une deuxieme partie, ces modeles sont appliques aux donnees relatives a des molecules nematiques de faible masse moleculaire ainsi qu'a des polymeres nematiques. Cette application permet d'obtenir des informations sur la structure et les mouvements internes a la molecule, l'ordre orientationnel regnant au sein de la phase et les proprietes visco-elastiques du materiau etudie. Enfin, on montre que l'extension de ces modeles aux donnees rmn de polymeres ne presentant pas de phase nematique en phase pure permet d'obtenir des informations similaires en considerant que leur phase amorphe presente localement un ordre nematique