Confinement effects on the nuclear spin isomer conversion of H$_2$O

TL;DR

This study investigates how confinement within Argon matrices influences the nuclear spin isomer conversion rates of H₂O, revealing new pathways and mechanisms that could impact spectroscopy, storage, and astronomical observations.

Contribution

It uncovers the role of confinement effects in enhancing NSI interconversion rates of H₂O and suggests intramolecular pathways that were previously unrecognized.

Findings

Confinement increases NSI conversion rates in H₂O.

New intramolecular pathways for isomer conversion are identified.

Implications for spectroscopy, storage, and astrophysical measurements.

Abstract

The mechanism for interconversion between the nuclear spin isomers (NSI) of H$_2$O remains shrouded in uncertainties. The temperature dependence displayed by NSI interconversion rates for H$_2$O isolated in an Argon matrix provides evidence that confinement effects are responsible for the dramatic increase in their kinetics with respect to the gas phase, providing new pathways for o-H$_2$O $\leftrightarrow$ p-H$_2$O conversion in endohedral compounds. This reveals intramolecular aspects of the interconversion mechanism which may improve methodologies for the separation and storage of NSI en route to applications in nuclear magnetic resonance spectroscopy and imaging. It may also improve astronomers' ability to use their relative abundance in the interstellar medium as proxies, thereby providing a valuable "astronomical clock".