Nuclear quadrupole resonances in compact vapor cells: The crossover between the NMR and the nuclear quadrupole resonance interaction regimes

Abstract

We present an experimental study that maps the transformation of nuclear quadrupole resonances (NQRs) 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. The large nuclear quadrupole shifts present in our system enable us to study this regime with relatively high resolution. We achieve large nuclear quadrupole shifts for $I=3∕2$ $^{131}\mathrm{Xe}$ by using a cube-shaped $1\phantom{\rule{0.3em}{0ex}}{\mathrm{mm}}^{3}$ vapor cell with walls of different materials. The enhancement of the NQR shift from the cell wall materials is an observation that opens up an additional adjustable parameter to tune and enhance the nuclear quadrupole interactions in vapor cells. As a confirmation that the interesting and complex spectra that we observe are indeed expected, we compare our data to numerical calculations and find excellent agreement.