Preparation, characterization and storage of water vapours highly enriched in its ortho-H2O nuclear spin isomer

Quantum State-Resolved Characterization of a Magnetically Focused Beam of ortho-H2O

“…Magnetic focusing − relies on a different physical principle for the separation of NSI than electric deflection − and thus it provides a complementary quantum-state selection and enrichment strategy that is uniquely suited for many applications. For example, magnetic focusing would be the preferred technique for optimizing the transfer of spin polarization from the gas phase to surfaces or to the condensed phase (e.g., inert matrices, ice), en route toward the development of hyperpolarised nuclear magnetic resonance methodologies .…”

“…23,24 Depositing molecules from the magnetically focused beam, and trapping them in a growing rare gas matrix, also has significant drawbacks as NSI interconversion results in an erosion of the enrichment in ortho-H 2 O which required extrapolation of the interconversion kinetics backward to evaluate the initial NSI populations in the beam. 25 Furthermore, this procedure cannot take into account any impulsive NSI conversion dynamics that may occur as a result of the collision of water molecules with the matrix upon deposition from the beam, neither can it reveal the occurrence of faster relaxation mechanisms which take place before a significant IR signal can be acquired. 25 In this paper, we report the direct determination of the NSI distribution, and the rotational temperature, of water molecules in a magnetically focused molecular beam also using REMPI-TOF-MS characterization and compare the merits of this enrichment strategy with those reported for the electric deflection method.…”

“…25 Furthermore, this procedure cannot take into account any impulsive NSI conversion dynamics that may occur as a result of the collision of water molecules with the matrix upon deposition from the beam, neither can it reveal the occurrence of faster relaxation mechanisms which take place before a significant IR signal can be acquired. 25 In this paper, we report the direct determination of the NSI distribution, and the rotational temperature, of water molecules in a magnetically focused molecular beam also using REMPI-TOF-MS characterization and compare the merits of this enrichment strategy with those reported for the electric deflection method. 18,19 Quantum state-resolved imaging of the molecular beam cross-sectional spatial profiles reveals that magnetic focusing produces a high flux beam enriched in the ortho-H 2 O NSI to a purity comparable to that achieved by electric deflection.…”

“…23,24 Alternatively, trapping water molecules from the magnetically focused beam by embedding them in a growing krypton matrix at cryogenic temperature, where their rotational motion as essentially unhindered, enabled the evolution of their nuclear spin-state distributions to be probed using rovibrational spectroscopy. 25 While both of these detection techniques suggested that a sizable enrichment in ortho-H 2 O could be achieved using magnetic focusing, their indirect nature leads to inherent uncertainties when quantifying the NSI composition of the beam. In particular, extracting the isomer composition from beam profiles is plagued with uncertainties because of the beam properties (i.e., velocity and angular distributions, velocity slip) as well as the magnitude of the contribution from the rotational magnetic moment of the water molecules to magnetic focusing, an effect which can however safely be neglected for rotationally cold beams.…”

“…This, combined with spin-based selection afforded by magnetic focusing, makes this methodology particularly well-suited for condensed-phase applications where spin-polarised samples of water (or other molecules) are desired, for example, to create molecularly thin magnetically ordered layers. Until now, separation of the NSI of water by magnetic focusing in a molecular beam was detected indirectly, for example, by spatial profiling of the beam using a moving aperture and a mass spectrometer. , Alternatively, trapping water molecules from the magnetically focused beam by embedding them in a growing krypton matrix at cryogenic temperature, where their rotational motion as essentially unhindered, enabled the evolution of their nuclear spin-state distributions to be probed using rovibrational spectroscopy . While both of these detection techniques suggested that a sizable enrichment in ortho -H 2 O could be achieved using magnetic focusing, their indirect nature leads to inherent uncertainties when quantifying the NSI composition of the beam.…”