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dc.contributor.advisorRamanathan, K V
dc.contributor.authorDas, Bibhuti Bibhudutta
dc.date.accessioned2010-09-06T11:12:21Z
dc.date.accessioned2018-07-31T06:20:37Z
dc.date.available2010-09-06T11:12:21Z
dc.date.available2018-07-31T06:20:37Z
dc.date.issued2010-09-06
dc.date.submitted2008
dc.identifier.urihttps://etd.iisc.ac.in/handle/2005/859
dc.description.abstractDipolar couplings are one of the major source of structural information. Due to their dependence on the distance between the nuclei and the angle of orientation of the dipolar vector with respect to the magnetic field, they provide significant insight into the geometry and topology of molecules. As the dipolar interactions are in general present in the solid phase of the compounds, solid state NMR experiments have gained significant popularity and is widely used. Separated Local Field NMR spectroscopy based on cross-polarization technique has been used to measure the heteronuclear dipolar couplings in solid state. However, the technique undergoes many experimental challenges and requires further development. This thesis is concerned mainly with the development of techniques to measure the dipolar couplings accurately in oriented molecules. In this regard, a method for fast data acquisition is also proposed. The first chapter briefly introduces the basics of NMR spectroscopy, methodologies applied for obtaining a high resolution NMR spectrum in the solid state. An introduction to liquid crystals is presented and the nature of NMR interaction in the liquid crystalline phases is described. In chapter-2, a new pulse scheme has been proposed that includes the X-nucleus polarization in the SLF experiments and is shown to provide better sensitivity and resolution. A quantitative analysis with simulation and experimental results are also presented. In chapter-3, the performance of various homonuclear decoupling pulse schemes incorporated into SLF experiments tested on oriented systems are compared. The proposed pulse schemes are shown to provide high resolution spectrum with accurate dipolar coupling measurement for natural abundant samples and for uniformly labeled compounds as well. Theoretical description with simulation and experimental results shown here are found to provide optimum results under several technical complications seen with respect to the conventional methods used for SLF experiments. Chapter-4, an attempt is made to reconstruct 2D J-resolved and 2D- SLF spectra from several 1D experimental data. This is achieved with the help of projection reconstruction method and is shown to provide high resolution 2D spectrum with saving of experimental time by an order of two. Chapter-5, high resolution spectra from SLF experiments under phase alternating pulses and using amplitude and time averaged nutation techniques are shown for accurate dipolar coupling measurement with a dramatic reduction in rf power. This is important as the use of low rf power leads to low sample heating and can be applied suitably for the study of liquid crystals and salty biomolecules. Chapter-6, attempts are made to characterize two novel thiophene based liquid crystals using both solution and solid state NMR spectroscopy. C-H dipolar couplings measured from SLF experiments are mainly used to find the order parameters and geometry of the molecules.en_US
dc.language.isoen_USen_US
dc.relation.ispartofseriesG22354en_US
dc.subjectDisordered Systems (Physics)en_US
dc.subjectNuclear Magnetic Resonanceen_US
dc.subjectDipolar Couplingsen_US
dc.subjectSeparated Local Field NMR Spectroscopyen_US
dc.subjectNuclear Spinen_US
dc.subjectHamiltoniansen_US
dc.subjectSolid State NMRen_US
dc.subject2D-SLF Experimentsen_US
dc.subjectSLF Spectroscopyen_US
dc.subjectCross-polarizationen_US
dc.subjectThiopheneen_US
dc.subjectInitial Density Matrixen_US
dc.subject.classificationSolid State Physicsen_US
dc.titleSeparated Local Field NMR Spectroscopy In Partially Ordered Systems - New Methodologies And Applicationsen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.disciplineFaculty of Scienceen_US


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