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

Metrologia

Spin Dependent Charge Transfer in Low-Energy Collisions between Helium Ions and Cesium Atoms

Hans A. Schuessler

Published Jul 1, 1977• 8 citations
Publisher

Abstract

The experiment demonstrated that total spin angular momentum is conserved in the near resonant charge transfer collisions between oriented helium ions and oriented cesium atoms. The resulting spin dependence of the total charge transfer cross-sections is described using singlet and triplet channels based on the molecular potential energy curves of the collision pair. The experiment was performed with helium ions stored in a rf-quadrupole trap in interaction with an optically pumped beam of cesium atoms. Total spin dependent charge transfer cross-sections were measured in the energy range of a few eV.

DOI
10.1088/0026-1394/13/3/005

Related papers

Angular Momentum Transfer at the Chemo-ionization and Spin Exchange Processes. Interaction between Spin Polarized Metastable Helium Atoms

Victor A. Kartoshkin

In the collision of spin-polarized atoms, the transmission of electron polarization between colliding particles is possible. A similar situation occurs in a collision, for example, between alkali atoms in the ground state. If one of the colliding particles is in an excited state and its energy is sufficient for ionization of the collision partner, then along with the elastic process (spin exchange), an inelastic process (ionization) is also possible, as a result of these processes polarization can also be transferred to the partner. Simultaneously occurring elastic and inelastic processes at the collision between two helium atoms are possible if these atoms are in the metastable (23S1) state. The paper discusses the interaction between spin-polarized metastable atoms of helium-3 and helium-4 isotopes under conditions of optical pumping of atoms. Complex interaction potentials of the atoms under consideration were constructed and on their basis, the spin exchange and chemo-ionization cross-sections were calculated. Using these cross-sections, expressions for the transfer of orientation and alignment from one atom to another were obtained.

Mediterranean Journal of Chemistry•Oct 7, 2022•0 citations

Electron Collisions with Laser Cooled and Trapped Metastable Helium Atoms: Total Scattering Cross Sections

L. J. Uhlmann, R. G. Dall, Andrew G. Truscott +3 more

Absolute measurements of total scattering cross sections for low energy (5-70 eV) electrons by metastable helium (2(3)S) atoms are presented. The measurements are performed using a magneto-optical trap which is loaded from a laser-cooled, bright beam of slow He(2(3)S) atoms. The data are compared with predictions from convergent close coupling and R matrix with pseudostate calculations, and we find good agreement between experiment and theory.

Physical Review Letters•May 3, 2005•36 citations

Elastic and charge-transfer collisions of He + –He at ultralow energies

Syham Lias, Fouzia Bouchelaghem, L. Aissaoui

Abstract Elastic, momentum-transfer (diffusion), and non-radiative charge-transfer cross sections are calculated for collisions between ground-state He + ( 2 S) ions and neutral He( 1 S) atoms over an energy range spanning fourteen orders of magnitude, from 10 −12 to 1 atomic unit. In this ultralow-energy regime, quantum mechanical effects dominate and the indistinguishability of helium nuclei necessitates a rigorous treatment of exchange symmetry. Phase shifts are computed using highly accurate ab initio potential energy curves for the X 2 Σ u and A 2 Σ g molecular states. The resulting elastic σ el , diffusion σ d , and charge-transfer σ ct cross sections reveal three distinct regimes: at energies below 10 −9 a.u., cross sections exceed 10 5 a 0 2 and are dominated by long-range polarization forces; in the intermediate range (10 −8 –10 −4 a.u.), pronounced quantum interference structures appear; at higher energies, results converge to semiclassical E −1/3 behavior. The data provide benchmark cross sections for ultracold ion–atom collision modeling relevant to cold-ion physics and hybrid atom–ion trapping experiments.

Journal of Physics B Atomic Molecular and Optical Physics•Apr 15, 2026•1 citation

Orientation of diamagnetic Cs+ions by charge-exchange collisions with optically pumped caesium

A. F. Oluwole, E A Togun

A charge-exchange optical pumping experiment to study collisions between Cs atoms and Cs + ions in a He buffer gas is reported. Cs + ions are polarized by charge-exchange collisions with optically pumped Cs atoms. From measurements of the line-widths of the Cs + ion resonance and electron spin resonance, the charge- exchange cross section sigma ce (Cs + -Cs) and electron spin-exchange cross section sigma se (e-Cs)are found to be sigma ce (Cs*-Cs)=(4.5+or-0.5)*10 -14 cm 2 and sigma se (e-Cs)=(2.6+or-0.4)*10 -14 cm 2 respectively.

Journal of Physics B Atomic and Molecular Physics•Nov 1, 1973•7 citations

Depolarization of 6P322 cesium atoms, induced in collisions with noble gases

J. Guiry, L. Krause

Cross sections for relaxation of circular and linear polarization of $6^{2}P_{\frac{3}{2}}$ cesium atoms, induced in collisions with ground-state He, Ne, Ar, and Xe, have been determined by Zeeman scanning techniques. A fluorescence cell containing low-pressure cesium vapor together with a buffer gas was irradiated with circularly or linearly polarized 8521-\AA{} Cs resonance radiation, producing excited and polarized Cs atoms which became depolarized in subsequent collisions with the buffer-gas atoms. The resulting depolarization of the cesium resonance fluorescence was monitored in relation to buffer-gas pressure (0-10 Torr) and to the strength of the ambient magnetic field (0-10 kG). At low fields at which the nuclear spin $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ is coupled to the electronic angular momentum $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$, the measurements yielded depolarization cross sections $Q(\mathrm{circ}.)$ and $Q(\mathrm{lin}.)$, which agree within experimental error with theoretical values calculated for spin-coupled conditions. At kilogauss fields with $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ and $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$ decoupled, the experiments produced cross sections for disorientation and disalignment, which are also in satisfactory agreement with the appropriate theoretical predictions. The results indicate that the nuclear spin has a more pronounced effect on the collisional relaxation of the atomic dipole than of the quadrupole.

Physical Review A•Dec 1, 1976•13 citations

Energy-dependent relative charge transfer cross sections of Cs++ Rb(5s, 5p)

Hai Truong Nguyen, R. Brédy, X. Fléchard +1 more

Magneto optical trap recoil ion momentum spectroscopy is used to measure energy-dependent charge exchange cross sections in the Cs+ + Rb(5s, 5p) system over a range of projectile energies from 3.2 to 6.4 keV. The measurements are kinematically complete and yield cross sections that are differential in collision energy, scattering angle, and initial and final states.

arXiv:1306.4112•Journal of Physics B Atomic Molecular and Optical Physics•May 10, 2013•1 citation
The experiment demonstrated that total spin angular momentum is conserved in the near resonant charge transfer collisions between oriented helium ions and oriented cesium atoms. The resulting spin dependence of the total charge transfer cross-sections is described using singlet and triplet channels based on the molecular potential energy curves of the collision pair. The experiment was performed with helium ions stored in a rf-quadrupole trap in interaction with an optically pumped beam of cesium atoms. Total spin dependent charge transfer cross-sections were measured in the energy range of a few eV.
In the collision of spin-polarized atoms, the transmission of electron polarization between colliding particles is possible. A similar situation occurs in a collision, for example, between alkali atoms in the ground state. If one of the colliding particles is in an excited state and its energy is sufficient for ionization of the collision partner, then along with the elastic process (spin exchange), an inelastic process (ionization) is also possible, as a result of these processes polarization can also be transferred to the partner. Simultaneously occurring elastic and inelastic processes at the collision between two helium atoms are possible if these atoms are in the metastable (23S1) state. The paper discusses the interaction between spin-polarized metastable atoms of helium-3 and helium-4 isotopes under conditions of optical pumping of atoms. Complex interaction potentials of the atoms under consideration were constructed and on their basis, the spin exchange and chemo-ionization cross-sections were calculated. Using these cross-sections, expressions for the transfer of orientation and alignment from one atom to another were obtained.
Abstract Elastic, momentum-transfer (diffusion), and non-radiative charge-transfer cross sections are calculated for collisions between ground-state He + ( 2 S) ions and neutral He( 1 S) atoms over an energy range spanning fourteen orders of magnitude, from 10 −12 to 1 atomic unit. In this ultralow-energy regime, quantum mechanical effects dominate and the indistinguishability of helium nuclei necessitates a rigorous treatment of exchange symmetry. Phase shifts are computed using highly accurate ab initio potential energy curves for the X 2 Σ u and A 2 Σ g molecular states. The resulting elastic σ el , diffusion σ d , and charge-transfer σ ct cross sections reveal three distinct regimes: at energies below 10 −9 a.u., cross sections exceed 10 5 a 0 2 and are dominated by long-range polarization forces; in the intermediate range (10 −8 –10 −4 a.u.), pronounced quantum interference structures appear; at higher energies, results converge to semiclassical E −1/3 behavior. The data provide benchmark cross sections for ultracold ion–atom collision modeling relevant to cold-ion physics and hybrid atom–ion trapping experiments.
A charge-exchange optical pumping experiment to study collisions between Cs atoms and Cs + ions in a He buffer gas is reported. Cs + ions are polarized by charge-exchange collisions with optically pumped Cs atoms. From measurements of the line-widths of the Cs + ion resonance and electron spin resonance, the charge- exchange cross section sigma ce (Cs + -Cs) and electron spin-exchange cross section sigma se (e-Cs)are found to be sigma ce (Cs*-Cs)=(4.5+or-0.5)*10 -14 cm 2 and sigma se (e-Cs)=(2.6+or-0.4)*10 -14 cm 2 respectively.
Cross sections for relaxation of circular and linear polarization of 62P326^{2}P_{\frac{3}{2}}62P23​​ cesium atoms, induced in collisions with ground-state He, Ne, Ar, and Xe, have been determined by Zeeman scanning techniques. A fluorescence cell containing low-pressure cesium vapor together with a buffer gas was irradiated with circularly or linearly polarized 8521-\AA{} Cs resonance radiation, producing excited and polarized Cs atoms which became depolarized in subsequent collisions with the buffer-gas atoms. The resulting depolarization of the cesium resonance fluorescence was monitored in relation to buffer-gas pressure (0-10 Torr) and to the strength of the ambient magnetic field (0-10 kG). At low fields at which the nuclear spin $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ is coupled to the electronic angular momentum $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$, the measurements yielded depolarization cross sections Q(circ.)Q(\mathrm{circ}.)Q(circ.) and Q(lin.)Q(\mathrm{lin}.)Q(lin.), which agree within experimental error with theoretical values calculated for spin-coupled conditions. At kilogauss fields with $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ and $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$ decoupled, the experiments produced cross sections for disorientation and disalignment, which are also in satisfactory agreement with the appropriate theoretical predictions. The results indicate that the nuclear spin has a more pronounced effect on the collisional relaxation of the atomic dipole than of the quadrupole.