The use of proton nuclear magnetic resonance (NMR) spectroscopy as an on-line continuous flow detector for liquid chromatography (LC-¹H NMR) is described. Flow inserts for electromagnet and superconducting solenoid magnets are described. Applications to fuel analysis are presented. LC-¹H NMR is shown to be an informative technique. The principle limitation is sensitivity. Conditions for quantitative flow pulse NMR measurements are presented. An average composition method for fuel samples (based on LC-¹H NMR) is derived. This method is shown to be of value in characterizing the aromatic fractions of low boiling fuels. Average degrees of substitution, number average molecular weights, and other quantities can be determined with this method. A theoretical description of flow NMR experiments is developed. The classical description of magnetization (based on the Bloch equations) and detailed physical pictures of flow are combined in computer simulations. Several examples are given and computer program listings are appended. / Ph. D.

The technique of high resolution solid state carbon-13 NMR, achieved with magic angle spinning (MAS) and high power 13c-1H dipolar decoupling and cross polarization, was applied to a number of multicomponent polymer systems. Specific problems which were addressed are: (1) the nature of domain structure and molecular motion of two thermoplastic elastomer systems, including a series of styrene isoprene-styrene linear triblock copolymers (SIS’s) of various compositions, molecular weights and sample histories, and a poly(ester)- urethane based on poly(1,4-butylene adipate) and 4,4¹ -diphenylmethane diisocyanate, (2) the compatibility at the molecular level of polymer blends containing poly{vinylidene fluoride) (PVF2), including solution and mechanical blends with poly{methyl methacrylate) {PMMA}, poly(vinyl acetate} (PVAc) and poly(vinyl methyl ether) (PVME). For the thermoplastic copolymers, higher degree of phase separation between the hard and soft domains was indicated by two facts: First, ¹³C resonances of either domain could be selectively observed with different experimental conditions. Second, there was a one-component, first-order, spin-lattice relaxation behavior of the ¹³C nuclei in the soft domains. For the SIS copolymers, results of T₁ and T₂* determinations (beth with MAS) suggest that molecular motion, in terms of frequency, was independent of composition, molecular weight and selective casting solvents. However, from static spectra, molecular motion of the isoprene blocks was found to be more anisotropic for the samples cast from a poor solvent for polyisoprene {MEK) in contrast to samples cast from a good solvent of polyisoprene (hexane). For the polymer blends of poly(vinylidene fluoride), the level of molecular intermixing was reflected through the degree of ¹³C NMR signal attenuations of the non-PVF₂ polymers. These attenuations are mainly due to undecoupled intermolecular ¹³C-¹⁹F dipolar interactions. With a MAS rate of 2KHz, resolution of the intimacy of mixing between the two constituent polymers in the blends was estimated to be in the range of 3 to 4 angstroms. Varying degrees of NMR signal attenuations among the individual chemically different carbons of a polymer support a postulation of weak intermolecular 'acid-base' association between the acidic protons of PVF₂ and basic carbonyl groups in the case of both the PMMA and PVAc. / Ph. D.

This paper describes a new technique for analyzing fire debris using nuclear magnetic resonance (NMR) spectroscopy. Petroleum distillates, which are commonly used accelerants, were weathered, burned, and steamdistilled. These, as well as virgin samples of the accelerants, were analyzed by gas chromatography and nuclear magnetic resonance spectroscopy. In addition, solvent studies and detectibility limit studies were conducted. The use of NMR is described as a valuable adjunct to the existing methods of analysis.

No description available.

Nuclear magnetic resonance force microscopy (NMRFM) is a technique that combines aspects of scanning probe microscopy (SPM) and nuclear magnetic resonance (NMR) to obtain 3 dimensional nanoscale spatial resolution and perform spectroscopy. We describe the components of a helium-3 NMRFM probe and studies of ammonium sulfate ((NH₄)₂SO₄) and magnesium diboride (MgB₂). For our room temperature (NH₄)₂SO₄ studies we were able to perform a 1-D scan and perform nutation and spin echo experiments. In our 77 K MgB₂ we demonstrate a 1-D scan of a 30 micron powder sample. In addition, we describe magnetic measurements of the possible dilute semiconductors Mn[subscript x]Sc[subscript 1-x]N and Fe₀.₁Sc₀.₉N. / text

[Truncated abstract] This thesis describes the development of synthetic rock samples, representative of core samples from hydrocarbon reservoirs. The basic process consists of screening and sorting silica particles into discrete grain sizes, and then binding them together using a proprietary process known as CIPS, (Calcite In-situ Precipitation System). In the bonding process, the porosity of the system is substantially preserved, and the technique allows the manufacture of synthetic core samples with a tailor-made permeability. The produced samples were extensively characterised using a variety of analytic techniques to determine their porosity, permeability and pore size distribution. These analyses were a necessary pre-cursor to a major part of this thesis: the characterisation of the pore space by nuclear magnetic resonance (NMR) techniques. The synthetic core samples, covering a 7 times factor in grain sizes were examined using NMR, and this data formed the comparative basis for the NMR studies that followed. Two fundamental NMR questions were posed and answered in this thesis: 1. What is the effect of paramagnetic ions in the rock matrix on the NMR response? In pursuit of this question the CIPS process was extended to include co-precipitation of paramagnetic ions. A key feature is that the ions were deposited in predictable amounts at known sites (on the wall of the pore space). ... The NMR response in these double cores was then measured and examined to provide an answer to the question posed at the beginning of this paragraph. The significance of this work is that the physically distinct cores are a cylindrical analogue of adjoining sedimentary strata. By answering the question posed above, the thesis gives an indication of the vertical porosity resolution ultimately possible in an NMR logging tool. At present this ranges from 9” to 24” in the most favourable circumstances. This work suggests that the NMR signal carries porosity information at a much higher resolution, and that advanced numerical analysis of the NMR signature could realise the potential of greater stratigraphic resolution in NMR logging In addition to the research outlined above, the application of the CIPS technique to produce analogues of reservoir rocks, pioneered in this thesis, has stimulated similar research to be undertaken at other institutions, including the fabrication of synthetic reservoir cores containing clay particles (at CSIRO - the Commonwealth Scientific and Industrial Research Organisation) and a large scale application, formation of meter size blocks of CIPS bonded material, with separate strata, for laboratory studies of seismic waves (at Curtin University)

Thesis (doctoral)--Lund University, 1998. / Thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Thesis statement inserted. Includes bibliographical references.

Abstract The rare-earth elements (REEs) and bismuth, being classified as the ‘most critical raw materials’ (European Raw Materials Initiatives, 2017), have a high economic importance to the EU combined with a high relative supply risk. REEs are highly important for the evolving technologies such as clean-energy applications, high-technology components, rechargeable batteries, permanent magnets, electric and hybrid vehicles, and phosphors monitors. This scientific research work aims at building a fundamental knowledge base concerning the electronic/molecular structure and properties of rare-earth element (REE) and bismuth complexes with dithiocarbamate (DTC) and 1,10-phenanthroline (PHEN) by employing state-of-the-art experimental techniques such as nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) techniques together with ab initio quantum mechanical computational methods. This combination of methods has played a vital role in analysing the direct and significant effect of the heavy metal ions on the structural and magnetic resonance properties of the complexes, thereby, providing a framework of structure elucidation. This is of special importance for REEs, which are known to exhibit similar chemical and physical properties. The objectives of the work involve i) a systematic investigation of series of REE(III) as well as bismuth(III) complexes to get a profound understanding of the structure-properties relationship and ii) to find an appropriate theoretical modelling and NMR calculation methods, especially, for heavy metal systems in molecular and/or solid-state. This information can later be used in surface interaction studies of REE/bismuth minerals with DTC as well as in design and development of novel ligands for extraction/separation of metal ions. The REE(III) and bismuth(III) complexes with DTC and PHEN ligands have all provided a unique NMR fingerprint of the metal centre both in liquid and solid phase. The solid-state ¹³C and ¹⁵N NMR spectra of the diamagnetic REE(III) and bismuth(III) complexes were in accord with their structural data obtained by single crystal XRD. The density functional theory (DFT) methods were used to get complementary and refined structural and NMR parameters information for all diamagnetic complexes in the solid-state. The relativistic contributions due to scalar and spin-orbit correlations for the calculated ¹H/¹³C/¹⁵N chemical shifts of REE complexes were analysed using two-component zeroth-order regular approximation (ZORA)/DFT while the ‘crystal-lattice’ effects on the NMR parameters were calculated by combining DFT calculations on molecular and periodic solid-state models. The paramagnetic REE complexes display huge differences in their ¹H and ¹³C NMR spectral patterns. The experimental paramagnetic NMR (pNMR) chemical shifts, as well as the sizable difference of the ¹H and ¹³C NMR shifts for these isoelectronic complexes, are well reproduced by the advanced calculations using ab initio/DFT approach. The accuracy of this approach is very promising for further applications to demanding pNMR problems involving paramagnetic f-block elements. The results presented in this thesis demonstrate that a multidisciplinary approach of combined experimental NMR and XRD techniques along with computational modelling and property calculations is highly efficient in studying molecular complexes and solids containing heavy metal systems, such as rare-earths and bismuth.

No description available.