Nuclear quadrupole resonances in compact vapor cells: the crossover from the NMR to the NQR interaction regimes

TL;DR

This study experimentally maps the transition of nuclear quadrupole resonances from the pure quadrupole regime to the Zeeman regime, revealing the quantum-mechanical nature of the axis change and validating a Liouvillian approach for theoretical predictions.

Contribution

First experimental mapping of nuclear quadrupole resonance transformation across interaction regimes, employing a Liouvillian approach for accurate theoretical modeling.

Findings

Observed large nuclear quadrupole shifts in 131-Xe

Transition from quadrupole to Zeeman regime mapped experimentally

Liouvillian approach matches experimental data well

Abstract

We present the first experimental study that maps the transformation of nuclear quadrupole resonances from the pure nuclear quadrupole regime to the quadrupole-perturbed Zeeman regime. The transformation presents an interesting quantum-mechanical problem, since the quantization axis changes from being aligned along the axis of the electric-field gradient tensor to being aligned along the magnetic field. We achieve large nuclear quadrupole shifts for I = 3/2 131-Xe by using a 1 mm^3 cubic cell with walls of different materials. When the magnetic and quadrupolar interactions are of comparable size, perturbation theory is not suitable for calculating the transition energies. Rather than use perturbation theory, we compare our data to theoretical calculations using a Liouvillian approach and find excellent agreement.