NMR Relaxation And Charge Transport In Conducting Polymers
Singh, Kshetrimayum Jugeshwar
MetadataShow full item record
Conducting and semiconducting polymers, consisting of delocalized π-electrons, have been studied for the past three decades. These materials have shown novel physical properties with interesting applications in batteries, detectors, light emitting diodes, field effect transistors, solar cells, biosensors etc. Nevertheless the charge transport properties are yet to be understood in detail due to the complexity of the system, especially due to the interplay of quasi-one dimensionality (q-1D), disorder, localization and electron-electron interactions(EEI). A combined investigation of both conductivity and spin lattice relaxation time, especially at very low temperatures and high magnetic fields, is really lacking in conducting polymers. In this thesis a set of experiments – dc conductivity, magnetoresistance (MR), Nuclear Magnetic Resonance (NMR) spin lattice relaxation time (T1) measurements, magnetic susceptibility amd ac conductivity have been carried out in conducting polymers. NMR being a local probe it is possible to get the nanoscopic scale charge transport mechanism. Further, this helps to develop a consistent understanding among a wide range of the physical properties in conducting polymers. In this thesis author has reported the results of experiments at ultra low temperature (mk) and ultra high magnetic field which give more insight about the roles of electron-electron interaction(EEI) and disorderin charge transport properties. This thesis describes a detailed study of charge transport and NMR relaxation in three representative conducting polymers namely polypyrrole(PPy)., poly-3-methylthiophene(P3MT) and poly3-hexylthiophene(P3HT). The emphasis is to understand the charge transport phenomena and NMR relaxation, especially at ultra low temperatures (down to 20 mk) and high magnetic field (up to 23.4 T). The NMR T1 relaxation mechanisms are discussed in terms of (i) Korringa relaxation, (ii) relaxation due to spin diffusion to paramagnetic centers (SDPC) amd (iii) reorientation of symmetric groups, depending upon the temperature range.
- Physics (PHY) 
Showing items related by title, author, creator and subject.
Microporous Membranes Derived using Crystallisation Induced Phase Separation in PVDF/PMMA (Polyvinylidene Fluoride/ Polymethyl Methacrylate) Blends in Presence of Multiwalled Carbon Nanotubes Sharma, Maya (2018-03-10)Segmental chain dynamics in polymer blends is a very important topic, not only from a fundamental point of view but also from technological applications. Because of the difficulties in the commercialization of new polymers, ...
Nuclear Quadrupole Resonance And Relaxation Studies In Chloropyridines And High Pressure Studies In Chlorates Amdjadi, Mohammed Hossein Ala (2012-12-04)
Roychowdhury, Swapan (2009-05-18)In this thesis, theoretical and computer simulation studies of vibrational phase relaxation in various molecular liquids are presented. That includes liquid nitrogen, both along the coexistence line and the critical isochore, ...