Nuclear spin-spin coupling in a van der Waals-bonded system: Xenon dimer

Abstract

Nuclear spin-spin coupling over van der Waals bond has recently been observed via the frequency shift of solute protons in a solution containing optically hyperpolarized 129 Xe nuclei. We carry out a first-principles computational study of the prototypic van der Waals-bonded xenon dimer, where the spin-spin coupling between two magnetically non-equivalent isotopes, J( 129 Xe − 131 Xe), is observable. We use relativistic theory at the four-component Dirac-Hartree-Fock and Diracdensity-functional theory levels using novel completeness-optimized Gaussian basis sets and choosing the functional based on a comparison with correlated ab initio methods at the nonrelativistic level. J-coupling curves are provided at different levels of theory as functions of the internuclear distance in the xenon dimer, demonstrating cross-coupling effects between relativity and electron correlation for this property. Calculations on small Xe clusters are used to estimate the importance of many-atom effects on J( 129 Xe − 131 Xe). Possibilities of observing J( 129 Xe − 131 Xe) in liquid xenon are critically examined, based on molecular dynamics simulation. A simplistic spherical model is set up for the xenon dimer confined in a cavity, such as in microporous materials. It is shown that the on the average shorter internuclear distance enforced by the confinement increases the magnitude of the coupling as compared to the bulk liquid case, rendering J( 129 Xe − 131 Xe) in a cavity a feasible target for experimental investigation.

Systematic T1 improvement for hyperpolarized 129xenon

“…In [40] for example, computational studies of the nuclear spin-spin coupling, J, between magnetically non-equivalent nuclei J( 129 Xe-131 Xe) were performed. Although this coupling is about a factor of 20 less than the corresponding spin-rotation coupling discussed in the paper of Chann et al [18] it may be seen as a first step to look for other possible interactions of importance for a 129 Xe nucleus in a Xe-Xe pair.…”

Electron and nuclear spin polarization in Rb-Xe spin-exchange optical hyperpolarization

“…The exponents of this basis set are listed in Table I of the Supplemental Material of Ref. [50]. Using the final basis, the basis-set error of the HFCCs was monitored to be maximally about 1% at the NR B3LYP level (representing DFT in general here) at Rb-Xe internuclear distances of 3.6 and 4.6Å.…”

“…For the development of the basis set, we used a local version of the KRUUNUNHAKA basis-set toolkit that employs the completeness-optimization method [45], like in our earlier publications [46][47][48][49][50]. The same final, uncontracted basis was used for both Rb and Xe atoms as the completeness-optimized basis sets are element independent.…”

Dipolar and scalar He3−Xe129 frequency shifts in stemless cells

“…It also can be used in NMR metrology applications instead of spherical cells that are hard to fabricate without stems [31].Excellent control of long-range dipolar fields also allows us to resolve a small scalar frequency shift between 3 He and 129 Xe nuclear spins mediated by second-order electron interactions. Such through-space J I 1 ·I 2 coupling in van der Waals molecules has been theoretically studied in several systems [32][33][34][35] and was only observed experimentally between 129 Xe and 1 H in a liquid mixture of Xe and pentane [36]. Here we report the first observation of J-coupling between atomic spins in a gas mixture [37].…”