Anomalous longitudinal relaxation of nuclear spins in CaF$_2$

TL;DR

This paper explores the theoretical prediction and experimental feasibility of observing anomalous longitudinal relaxation of nuclear spins in CaF$_2$ caused by non-secular resonances under strong magnetic fields.

Contribution

It demonstrates the potential to experimentally observe non-secular resonance effects leading to anomalous relaxation in nuclear magnetic resonance of CaF$_2$.

Findings

Non-secular resonances can cause measurable anomalous relaxation.

Experimental observation of this effect in CaF$_2$ is feasible.

The study bridges theoretical predictions with practical NMR experiments.

Abstract

We consider the effect of non-secular resonances for interacting nuclear spins in solids which were predicted theoretically to exist in the presence of strong static and strong radio-frequency magnetic fields. These resonances imply corrections to the standard secular approximation for the nuclear spin-spin interaction in solids, which, in turn, should lead to an anomalous longitudinal relaxation in nuclear magnetic resonance experiments. In this article, we investigate the feasibility of the experimental observation of this anomalous longitudinal relaxation in calcium fluoride (CaF$_2$) and conclude that such an observation is realistic.