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

Area of Science:

• Quantum chemistry
• Nuclear magnetic resonance (NMR) spectroscopy
• Materials science

Background:

• Nuclear spin-spin coupling across van der Waals bonds has been experimentally observed.
• This phenomenon involves optically hyperpolarized 129Xe nuclei and frequency shifts of solute protons.
• Understanding this coupling is crucial for advanced NMR applications and probing van der Waals interactions.

Purpose of the Study:

• To computationally investigate nuclear spin-spin coupling (J-coupling) between xenon isotopes (129Xe and 131Xe) in a xenon dimer.
• To explore the influence of relativistic effects and electron correlation on J-coupling.
• To assess the feasibility of observing J((129)Xe - (131)Xe) in bulk liquid xenon and confined environments.

Main Methods:

• First-principles relativistic quantum chemical calculations (Dirac-Hartree-Fock, Dirac-density-functional theory).
• Use of novel completeness-optimized Gaussian basis sets.
• Molecular dynamics simulations to study liquid xenon and confined xenon dimers.

Main Results:

• J-coupling curves for the xenon dimer were computed as a function of internuclear distance.
• Significant cross-coupling effects between relativity and electron correlation were identified.
• Calculations suggest that J((129)Xe - (131)Xe) is more pronounced in confined xenon (e.g., in microporous materials) than in bulk liquid xenon.

Conclusions:

• The study provides a theoretical framework for understanding nuclear spin-spin coupling in van der Waals systems.
• Confinement in cavities enhances J((129)Xe - (131)Xe), making it a promising target for experimental observation.
• This research opens avenues for utilizing J-coupling in xenon-based NMR studies within confined environments.