Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Nuclear-spin-polarization dynamics of H 2 , D 2 , and HD molecules in magnetic fields

Chrysovalantis S. Kannis, George E. Katsoprinakis, Dimitris Sofikitis, Theodore Peter Rakitzis

Published Oct 18, 2018• 6 citations
Publisher

Abstract

We study the polarization dynamics of the molecular rotation and the nuclear spin in the presence of magnetic fields, in the hydrogen isotope molecules, ${\mathrm{H}}_{2},\phantom{\rule{0.16em}{0ex}}{\mathrm{D}}_{2}$, and HD. If only the rotational or the nuclear angular momentum is polarized, polarization is transferred from one to the other and back in a oscillatory fashion, due to hyperfine quantum beats. Application of magnetic fields is shown to increase the frequencies of these oscillations and reduce their amplitude so that the polarization exchange can be strongly suppressed. We derive the time-averaged polarization as a function of the (static) magnetic field. Finally, we show, using continuous lasers, molecular beams, and static magnetic fields, that the molecular rotation polarization can be transferred and maintained in the nuclear spin, providing highly nuclear-spin-polarized molecules.

DOI
10.1103/physreva.98.043426

Related papers

Spin manipulation in atomic and molecular systems for nuclear spin applications

Chrysovalantis S. Kannis, R. Engels, T. El-Kordy +5 more

Nuclear spin polarization has important applications across various fields, including physics andmedicine. It also offers several advantages, such as cross-section enhancement, in the five-nucleonfusion reactions, namely the D–T and D–$^3$He reactions. This work presents a theoretical studyof spin dynamics in the hyperfine regime for selected atomic and molecular systems and exploresalternative techniques to generate or enhance nuclear spin polarization in these systems. Particularemphasis is placed on coherent spin manipulation strategies and the role of hyperfine interactions intransferring angular momentum from electronic (in atoms) or rotational (in molecules) to nucleardegrees of freedom.

•Jan 1, 2026•0 citations

Polarization of deuterium molecules

J. F. J. van den Brand, Henk Jan Bulten, M. Ferro-Luzzi +15 more

For molecular systems, spin relaxation is expected to be suppressed compared to the case of atoms, since the paired electrons in a hydrogen or deuterium molecule are chemically stable, and only weakly interact with the spin of the nucleus. Such systems would be largely insensitive to polarization losses due to spin-exchange collisions, to the interaction of the electron spins with external fields (e.g. the RF-field of a bunched charged-particle beam), and/or to the presence of container walls. Here, we discuss the results of a recent experiment where we obtained evidence that nuclear polarization is maintained, when polarized atoms recombine to molecules on a copper surface (in a magnetic field of 23 mT and at a density of about 1012 molecules⋅cm−3).

AIP conference proceedings•Jan 1, 1998•0 citations

Production of HD Molecules in Definite Hyperfine Substates

R. Engels, K. Grigoryev, Chrysovalantis S. Kannis +10 more

Polarized atomic beam sources have been in operation for many years to produce either nuclear polarized atomic hydrogen or deuterium beams. In recent experiments, such a source was used to polarize both isotopes independently at the same time. By recombination of the atoms, hydrogen-deuterium molecules with all possible nuclear spin combinations can be created. Those spin isomers are useful for further applications, like precision spectroscopy, as polarized targets for laser-particle acceleration, polarized fuel for fusion reactors, or as an option for future measurements of electric dipole moments.

arXiv:2002.02009•Physical Review Letters•Mar 18, 2020•9 citations

A note on the spin-polarization of hydrogen atoms in a helium–hydrogen gas mixture

G. V. Klement’ev, Victor A. Kartoshkin, Sergei P. Dmitriev +1 more

In a helium–hydrogen mixture at T = 300 K, the polarization degree of hydrogen spins, both electron and nuclear, was determined to be as high as (5 ± 1)%. The role of the main processes giving rise to the formation of spin-polarized H atoms has been discussed. It is shown that an effective transfer of angular momentum from the preliminarily optically oriented He * (2 3 S 1 ) atoms to the H atoms is not due to the direct chemi-dissociation of the H 2 molecules by the He * atoms alone, or due to Penning ionization of these molecules followed by the ion-molecular rearrangement reaction H 2 + + H 2 → H 3 + + H alone, but to their summary action. The relative importance of the two mechanisms depends on the rotational temperature and total gas pressure.

Physica Scripta•Aug 1, 1996•0 citations

Control of the nuclear spin of the 129Xe and 131Xe isotopes in the spin-exchange interaction with 87Rb atoms

Е. Н. Попов, К. А. Баранцев, A. N. Litvinov

Nuclear spin dynamics of the 129Xe and 131Xe isotopes in an external magnetic field B 0 is considered. Nuclear spin is pumped by the laser through 87Rb, which transfers the electron spin to the 129Xe and 131Xe nuclei in the spin-exchange interaction. The nuclear spin dynamics is controlled with a transverse magnetic field that causes nuclear magnetic resonance in both 129Xe and 131Xe isotopes. Numerical calculations are performed to find conditions at which the transverse component of the nuclear spin in the established motion is of maximum and the slope angle relative to the vector of the constant magnetic field B 0 is 45°. This regime is taken to be optimal for simulation of practical applications. It is also found that the pump of the nuclear spin of xenon is strongly attenuated when the rubidium polarization vector is turned to the plane perpendicular to the external magnetic field vector B 0.

Physics of Wave Phenomena•Apr 1, 2016•1 citation

Spin dynamics and ortho-para conversion in H$_{2}$O during the phase transition from gas to solid in external magnetic fields

Chrysovalantis S. Kannis, Ralf Engels, Nicolas Faatz +2 more

The spin dynamics of water ice in the presence of external magnetic fields are investigated. The employed model is based on the approach introduced by Buntkowsky et al. [Z. Phys. Chem. 222, 1049 (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 interplay between magnetic dipole-dipole interactions and magnetic field coupling. Two types of configurations are examined: (i) static, homogeneous fields, corresponding to a time-independent interaction, and (ii) spatially varying 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 the total spin projections are evaluated during the first tens of milliseconds following the gas-to-solid phase transition. For static homogeneous fields, we show that increasing field strength suppresses dipolar-induced depolarization. Assuming that all molecules are initially in the para state, we show that static homogeneous fields can drive the ortho population up to approximately $50\%$, whereas suitably chosen sinusoidal-field configurations can increase it beyond $90\%$. These results are relevant for schemes aiming to preserve or manipulate nuclear-spin polarization during deposition.

physics.chem-phCross-listedarXiv:2606.04242•Jun 4, 2026
We study the polarization dynamics of the molecular rotation and the nuclear spin in the presence of magnetic fields, in the hydrogen isotope molecules, H2,D2{\mathrm{H}}_{2},\phantom{\rule{0.16em}{0ex}}{\mathrm{D}}_{2}H2​,D2​, and HD. If only the rotational or the nuclear angular momentum is polarized, polarization is transferred from one to the other and back in a oscillatory fashion, due to hyperfine quantum beats. Application of magnetic fields is shown to increase the frequencies of these oscillations and reduce their amplitude so that the polarization exchange can be strongly suppressed. We derive the time-averaged polarization as a function of the (static) magnetic field. Finally, we show, using continuous lasers, molecular beams, and static magnetic fields, that the molecular rotation polarization can be transferred and maintained in the nuclear spin, providing highly nuclear-spin-polarized molecules.
Nuclear spin polarization has important applications across various fields, including physics andmedicine. It also offers several advantages, such as cross-section enhancement, in the five-nucleonfusion reactions, namely the D–T and D–3^33He reactions. This work presents a theoretical studyof spin dynamics in the hyperfine regime for selected atomic and molecular systems and exploresalternative techniques to generate or enhance nuclear spin polarization in these systems. Particularemphasis is placed on coherent spin manipulation strategies and the role of hyperfine interactions intransferring angular momentum from electronic (in atoms) or rotational (in molecules) to nucleardegrees of freedom.
For molecular systems, spin relaxation is expected to be suppressed compared to the case of atoms, since the paired electrons in a hydrogen or deuterium molecule are chemically stable, and only weakly interact with the spin of the nucleus. Such systems would be largely insensitive to polarization losses due to spin-exchange collisions, to the interaction of the electron spins with external fields (e.g. the RF-field of a bunched charged-particle beam), and/or to the presence of container walls. Here, we discuss the results of a recent experiment where we obtained evidence that nuclear polarization is maintained, when polarized atoms recombine to molecules on a copper surface (in a magnetic field of 23 mT and at a density of about 1012 molecules⋅cm−3).
Polarized atomic beam sources have been in operation for many years to produce either nuclear polarized atomic hydrogen or deuterium beams. In recent experiments, such a source was used to polarize both isotopes independently at the same time. By recombination of the atoms, hydrogen-deuterium molecules with all possible nuclear spin combinations can be created. Those spin isomers are useful for further applications, like precision spectroscopy, as polarized targets for laser-particle acceleration, polarized fuel for fusion reactors, or as an option for future measurements of electric dipole moments.
In a helium–hydrogen mixture at T = 300 K, the polarization degree of hydrogen spins, both electron and nuclear, was determined to be as high as (5 ± 1)%. The role of the main processes giving rise to the formation of spin-polarized H atoms has been discussed. It is shown that an effective transfer of angular momentum from the preliminarily optically oriented He * (2 3 S 1 ) atoms to the H atoms is not due to the direct chemi-dissociation of the H 2 molecules by the He * atoms alone, or due to Penning ionization of these molecules followed by the ion-molecular rearrangement reaction H 2 + + H 2 → H 3 + + H alone, but to their summary action. The relative importance of the two mechanisms depends on the rotational temperature and total gas pressure.
Nuclear spin dynamics of the 129Xe and 131Xe isotopes in an external magnetic field B 0 is considered. Nuclear spin is pumped by the laser through 87Rb, which transfers the electron spin to the 129Xe and 131Xe nuclei in the spin-exchange interaction. The nuclear spin dynamics is controlled with a transverse magnetic field that causes nuclear magnetic resonance in both 129Xe and 131Xe isotopes. Numerical calculations are performed to find conditions at which the transverse component of the nuclear spin in the established motion is of maximum and the slope angle relative to the vector of the constant magnetic field B 0 is 45°. This regime is taken to be optimal for simulation of practical applications. It is also found that the pump of the nuclear spin of xenon is strongly attenuated when the rubidium polarization vector is turned to the plane perpendicular to the external magnetic field vector B 0.
Spin dynamics and ortho-para conversion in H2_{2}2​O during the phase transition from gas to solid in external magnetic fields
The spin dynamics of water ice in the presence of external magnetic fields are investigated. The employed model is based on the approach introduced by Buntkowsky et al. [Z. Phys. Chem. 222, 1049 (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 interplay between magnetic dipole-dipole interactions and magnetic field coupling. Two types of configurations are examined: (i) static, homogeneous fields, corresponding to a time-independent interaction, and (ii) spatially varying 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 the total spin projections are evaluated during the first tens of milliseconds following the gas-to-solid phase transition. For static homogeneous fields, we show that increasing field strength suppresses dipolar-induced depolarization. Assuming that all molecules are initially in the para state, we show that static homogeneous fields can drive the ortho population up to approximately 50%50\%50%, whereas suitably chosen sinusoidal-field configurations can increase it beyond 90%90\%90%. These results are relevant for schemes aiming to preserve or manipulate nuclear-spin polarization during deposition.