Quadrupole interactions: NMR, NQR, and in between from a single viewpoint

Area of Science:

• Physics
• Chemistry
• Spectroscopy

Background:

• Nuclear spins with quantum numbers >1/2 interact with magnetic fields (NMR) or electric field gradients (NQR).
• NMR and NQR are typically viewed as distinct spectroscopic techniques representing extremes of interaction dominance.
• Understanding the continuum between these interactions is crucial for advanced spectroscopic analysis.

Purpose of the Study:

• To present a unified theoretical framework for nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR).
• To explore the continuum between NMR and NQR interactions from a single viewpoint.
• To derive solutions for quadrupole-perturbed NMR and Zeeman-perturbed NQR, and analyze signal polarization.

Main Methods:

• Utilized a Liouville-space approach, specifically the direct method.
• Avoided explicit operators and commutators, offering an alternative to Hamiltonian methods.
• Applied the method to spins with quantum numbers >1/2, focusing on spin 3/2.

Main Results:

• Derived solutions for both quadrupole-perturbed NMR and Zeeman-perturbed NQR.
• Demonstrated the continuum between NMR and NQR through a unified theoretical perspective.
• Examined and contrasted signal polarization in pure NMR versus pure NQR spectroscopy.

Conclusions:

• The direct Liouville-space method provides a unified approach to understanding NMR and NQR spectroscopy.
• This unified viewpoint is applicable to a wide range of nuclear spins, not limited to spin 3/2.
• The findings offer new insights into the relationship and transition between magnetic and electric interactions in nuclear spectroscopy.