Practical aspects of Zeeman-perturbed NQR spectroscopy using an adjustable electromagnet.

Area of Science:

• Solid-state NMR and Nuclear Quadrupole Resonance (NQR) spectroscopy.
• Quantum mechanics and magnetic resonance.
• Materials science and chemical analysis.

Background:

• Quadrupolar-perturbed solid-state NMR is limited by high magnetic field requirements.
• Traditional NQR faces challenges in measuring high-frequency transitions and precise quadrupolar parameters.
• Existing methods struggle with strongly quadrupolar isotopes due to technical limitations.

Purpose of the Study:

• To introduce a modern implementation of Zeeman-perturbed NQR spectroscopy.
• To overcome the limitations of traditional NMR and NQR methods for studying quadrupolar nuclei.
• To enable precise measurement of quadrupolar parameters using low magnetic fields.

Main Methods:

• Utilizing an adjustable electromagnet for Zeeman-perturbed NQR spectroscopy.
• Applying low magnetic fields (around 10⁻² T) where quadrupolar interaction dominates.
• Simulating spectra via exact diagonalization of the Zeeman-quadrupolar Hamiltonian.

Main Results:

• Successfully recorded ⁷⁹Br and ¹²⁷I Zeeman-perturbed NQR spectra for bromo- and iodobenzene powders.
• Achieved high precision in measuring quadrupolar coupling constant (C<0xE1><0xB5><0x92>) and asymmetry parameter (η).
• Measured a C<0xE1><0xB5><0x92>(¹²⁷I) of 2077.25 ± 1.49 MHz (η = 0.114 ± 0.008) for sym-triiodotrifluorobenzene in under an hour at room temperature.

Conclusions:

• The developed Zeeman-perturbed NQR approach effectively studies strongly quadrupolar isotopes.
• This method obviates the need for ultrahigh magnetic fields, making it broadly applicable.
• The technique offers a promising alternative for materials characterization and analysis.