Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

Abstract

Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantummechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics.The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nu-2 clei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy.The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an encoding module for the recently developed NMR remote detection experiment. The feasibility of using hyperpolarized xenon-129 gas as a sensor is discussed. This work also reports the use of an optical atomic magnetometer to detect the nuclear magnetization of Xe-129 gas, which has potential applicability as a detection module for NMR remote detection experiments.

A nuclear quadrupolar spin quantum heat engine

“…The spectrum of H 0 can be given as The form of the quadrupolar Hamiltonian can be found by replacing the quantum operators in the classical expression describing the energy of interaction between the gradient and quadrupole. Here we will not deal with the derivation which can be found in standard textbooks [38][39][40][41]. The quadrupolar Hamiltonian is mainly expressed in a tensorial form where the gradient tensor is in its principal axis frame.…”

“…Studying the electromagnetic interactions within a molecule is important for molecular structural analysis [38][39][40][41]. Such phenomenon has also extensive applications, for example in biological systems, and promises a new research area for the efficient energy harvesting and storage with quantum devices [42][43][44][45][46][47].…”

Quantum coherence resourced by the strong nuclear quadrupolar interaction

“…The investigation of intra-molecular interactions is the primary research topic of nuclear magnetic resonance (NMR) experiments, which holds significant importance in the analysis of molecular structure [28,29]. Additionally, this phenomenon holds immense potential for diverse applications, including in biological systems [30], and offers a promising research area for the creation of quantum entanglement [31][32][33][34][35], as well as exploring nano-scale thermal devices for efficient energy harvesting and storage [36][37][38][39][40].…”

“…Additionally, this phenomenon holds immense potential for diverse applications, including in biological systems [30], and offers a promising research area for the creation of quantum entanglement [31][32][33][34][35], as well as exploring nano-scale thermal devices for efficient energy harvesting and storage [36][37][38][39][40]. Chemical shift, J-coupling, dipole-dipole interaction, and quadrupole coupling are examples of intramolecular nuclear spin interactions [28,29]. Here, we focus on the strong quadrupole interaction.…”

Lithium-7 qNMR as a method to quantify lithium content in brines using benchtop NMR

“…These broad signals can be problematic to qNMR applications, since the signal will be spread out over a larger frequency range, effectively reducing the signal intensity and consequently the signal-to-noise ratio (SNR). 35 There are, however, a few reported applications that use quadrupolar nuclei in qNMR. [36][37][38] For example, in 2018 Fernandez and coworkers reported the quantitative analysis of boric acid in biocides using 11 B qNMR.…”