Journal Article

FZJ-2026-04062

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Spin dynamics and ortho–para conversion in H2O during the phase transition from gas to solid in external magnetic fields

Kannis, C. S. (Corresponding author) ; Engels, R. W.FZJ* ; Faatz, N.FZJ*RWTH* ; Pütz, S. J.FZJ* ; Büscher, M.FZJ*

2027
Elsevier Science Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.chemphys.2026.113422  doi:10.34734/FZJ-2026-04062

Abstract: The spin dynamics of water ice in the presence of external magnetic fields are investigated. The employedmodel is based on the approach introduced by Buntkowsky et al. (2008), which considers two nearest-neighbor water molecules and yields a four-spin system, as the abundant oxygen isotope has zero nuclear spin.The model is extended to include coupling to external magnetic fields, allowing us to analyze the interplaybetween magnetic dipole–dipole interactions and magnetic field coupling. Two types of configurations areexamined: (i) static, homogeneous fields, corresponding to a time-independent interaction, and (ii) spatiallyvarying sinusoidal fields in relative motion with the molecules, leading to a time-dependent interaction.All computations are performed within the density operator formalism. The ortho/para populations and thetotal spin projections are evaluated during the first tens of milliseconds following the gas-to-solid phasetransition. For static homogeneous fields, we show that increasing field strength suppresses dipolar-induceddepolarization. Assuming that all molecules are initially in the para state, we show that static homogeneousfields can drive the ortho population up to approximately 50%, whereas suitably chosen sinusoidal-fieldconfigurations can increase it beyond 90%. These results are relevant for schemes aiming to preserve ormanipulate nuclear-spin polarization during deposition.

Keyword(s): Nuclei and Particles (1st) ; Nuclear Physics (2nd)

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Contributing Institute(s):

1. Experimentelle Hadrondynamik (IKP-2)
2. Elektronische Eigenschaften (PGI-6)

Research Program(s):

1. 612 - Cosmic Matter in the Laboratory (POF4-612) (POF4-612)
2. DFG project G:(GEPRIS)533904660 - Eine vielseitige Polarisationsmethode für Teilchen mit einfachen Hyperfeinstrukturen (533904660) (533904660)

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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