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Auteurs principaux: Mclane, Nathan, Duckett, LeAnh, Dodson, Leah G.
Format: Preprint
Publié: 2025
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Accès en ligne:https://arxiv.org/abs/2510.16155
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_version_ 1866911631610478592
author Mclane, Nathan
Duckett, LeAnh
Dodson, Leah G.
author_facet Mclane, Nathan
Duckett, LeAnh
Dodson, Leah G.
contents Nuclear-spin conversion in molecular hydrogen is governed by strict symmetry rules that typically require magnetic fields or catalytic surfaces to break. Here we demonstrate that the intrinsic tensor composition of a non-magnetic molecular crystal field can impose and relax these rules without external fields. High-resolution infrared spectra of H$_2$ in crystalline CO$_2$ reveal large rank-2 (quadrupolar) crystal-field splittings of the $m$ sublevels, while nuclear-spin conversion occurs only through $Δm = 0$ channels. Replacing CO$_2$ with polar N$_2$O introduces rank-1 (dipole) components that partially open $Δm \neq 0$ pathways, while incorporation of paramagnetic NO$_2$ fully lifts the restriction. These results establish a direct correspondence between crystal-field tensor rank and nuclear-spin dynamics, introducing a general symmetry-based framework for designing and controlling spin-isomer populations and quantum-state connectivity in molecular solids.
format Preprint
id arxiv_https___arxiv_org_abs_2510_16155
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Environment-imposed selection rules for nuclear-spin conversion of H$_2$ in molecular crystals
Mclane, Nathan
Duckett, LeAnh
Dodson, Leah G.
Quantum Physics
Nuclear-spin conversion in molecular hydrogen is governed by strict symmetry rules that typically require magnetic fields or catalytic surfaces to break. Here we demonstrate that the intrinsic tensor composition of a non-magnetic molecular crystal field can impose and relax these rules without external fields. High-resolution infrared spectra of H$_2$ in crystalline CO$_2$ reveal large rank-2 (quadrupolar) crystal-field splittings of the $m$ sublevels, while nuclear-spin conversion occurs only through $Δm = 0$ channels. Replacing CO$_2$ with polar N$_2$O introduces rank-1 (dipole) components that partially open $Δm \neq 0$ pathways, while incorporation of paramagnetic NO$_2$ fully lifts the restriction. These results establish a direct correspondence between crystal-field tensor rank and nuclear-spin dynamics, introducing a general symmetry-based framework for designing and controlling spin-isomer populations and quantum-state connectivity in molecular solids.
title Environment-imposed selection rules for nuclear-spin conversion of H$_2$ in molecular crystals
topic Quantum Physics
url https://arxiv.org/abs/2510.16155