Journal Article

PUBDB-2025-03946

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Enhancement of nuclear spin transitions as a resonance effect of isotope substitution

Yachmenev, A. (Corresponding author) ; Vogt, E.CFEL*DESY*

2025
American Institute of Physics Melville, NY

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Please use a persistent id in citations: doi:10.1063/5.0300952  doi:10.3204/PUBDB-2025-03946

Abstract: Mixing of different components of the total nuclear spin in the rovibrational states of isolated molecules is extremely weak. It has only been observed in hyperfine spectra for few systems, including S$_2$Cl$_2$, SiF$_4$, PH$_3$, and SF$_6$. We perform variational calculations of nuclear quadrupole interactions in the rotational spectra of S$_2$Cl$_2$ and CH$_2$Cl$_2$ and analyze the effects of breaking the molecular symmetry by isotopic substitution of one of the chlorine atoms. This symmetry breaking significantly enhances the mixing of nuclear spin states and produces a distinct spin polarization pattern with opposite spin orientations on the different isotopes. This enhancement arises as a resonance effect driven jointly by differences in isotopic masses and nuclear quadrupole coupling constants and gives rise to electric and magnetic dipole transitions between states with different relative orientations of the nuclear spin.

Note: The full text is the author’s accepted manuscript of the article published in The Journal of Chemical Physics (AIP). The final version is available at DOI: https://doi.org/10.1063/5.0300952. Please make the fulltext file publicly accessible under DESY’s open access policy.

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Contributing Institute(s):

1. CFEL-CMI (FS-CFEL-CMI)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. Quantum-mechanical modeling of the dissociation of hydrogen bonds (101155136) (101155136)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2025

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