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

Electron capture from a directed Stark-Rydberg state: Fore-and-aft ratios

Dean M. Homan, Oleg P. Makarov, O. P. Sorokina, Keith B. MacAdam, Morten Lundsgaard, C. D. Lin, Naoki Toshima

Published Dec 1, 1998• 11 citations
Publisher

Abstract

Electron capture by ${\mathrm{Cs}}^{+},$ ${\mathrm{K}}^{+},$ or ${\mathrm{Li}}^{+}$ from a $\mathrm{Na}$ Rydberg target in an extreme Stark state of $n=24, m=0$ has been measured and compared with both a classical and a quantal calculation as a function of the reduced velocity $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.15\ensuremath{-}1.6.$ Peaks and shoulders are found at $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.25,$ 0.5, and 1.0 in the ratio of the measured capture cross sections for electronic charge polarization antiparallel and parallel to the ion-beam direction. A close-coupling calculation reveals similar features in the total capture cross sections near those same scaled velocities. A classical trajectory calculation attributes this structure to swapping of the electron between the two positive charge centers as they pass one another during the collision. The total classical capture cross section of a Rydberg atom having an upstream-directed charge distribution is shown to be the sum of five-and-greater-swap, three-swap, and one-swap contributions, which result in the structure near $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.25, 0.5,$ and 1.0, respectively.

DOI
10.1103/physreva.58.4565

Related papers

Anomalous final-state distributions of electrons captured from directed Rydberg states

Dean M. Homan, Keith B. MacAdam, M. J. Cavagnero

A classical model of singly charged ion collisions with Rydberg atoms in linear Stark states directed toward the oncoming ion beam predicts a bimodal distribution of final states resulting from electron capture. At a reduced velocity $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}{=v}_{\mathrm{ion}}{/v}_{\mathrm{Bohr}}=0.45,$ the calculated energy distribution of captured electrons peaks near the target binding energy ${E}_{i},$ but has a second peak at energies roughly ${E}_{i}/4.$ Analysis of the impact-parameter dependence of the capture probabilities indicates that the second peak arises from three-swap capture events. The decrease in binding energy of the captured electrons is attributed to excitation via united-atom rotational coupling.

Physical Review A•Jan 1, 1998•12 citations

Electron capture in multiply charged ion-Rydberg atom collisions in an external magnetic field

Jingxiong Lu, S Bradenbrink, Zvjezdana Roller-Lutz +1 more

Figure 4 contains a misplotted total cross section curve. The correct figure 4 is shown below. Figure 4. Contributions of `swaps' to the total charge exchange cross section (a) for k min initial target states, (b) one swap, (c) three swaps, (d) five swaps and (e) seven swaps.

Journal of Physics B Atomic Molecular and Optical Physics•Jul 25, 2000•2 citations

Slow collisions of ions with Rydberg atoms

Keith B. MacAdam

New experimental results have been obtained in collisions of singly charged ions with Na Rydberg atoms. (a) The distribution of final n states populated by electron capture shows non-monotonic variations of width with incident energy over the range 60-2100 eV. (b) The total capture cross section for alkali ions on Rydberg targets shows peaks and dips over the same energy range, correlated with particular reduced velocities v and the polarization of the exciting laser. (c) {ell}-Changing collision of Na{sup +} on Na(nd) targets, n=26 and 28, at low v preferentially transfer multiple units {h_bar} of orbital angular momentum under single-collision conditions, despite very large impact parameters. (d) Inelastic impacts of Na{sup f+} on Na 36s and 30p states, perturbed by electric fields, populate a strongly field-dependent mixture of nearby Stark levels. A synopsis of recent progress will be given.

Bulletin of the American Physical Society•Dec 1, 1992•0 citations

Angle and velocity variation of electron capture from a Stark state

Keith B. MacAdam, Dean M. Homan, Oleg P. Makarov +1 more

Total electron capture by K+ or Cs+ from a Na Rydberg n=24 extremal Stark state, aligned with a weak external electric field, has been measured as a function of the angle between the atoms’ electric dipole moment and the projectile beam in the reduced-velocity range ṽ=0.15 to 1.05. A novel “Stark barrel” is described that produces the arbitrarily directed uniform electric field, smoothly switchable in both magnitude and direction in under 2 μs. The results illustrate the importance of spatial effects as opposed to velocity matching for a full understanding of electron capture near ṽ=1.

AIP conference proceedings•Jan 1, 1997•0 citations

Final quantumnfstate analysis for multiply charged ion-circular Rydberg target collisions

Kevin R. Cornelius, R. E. Olson

The classical trajectory Monte Carlo method has been used to simulate fully stripped ion-circular Rydberg atom collisions. We report that the mechanisms that govern the capture process for ions colliding with aligned Rydberg targets, namely direct and indirect velocity matching, alternate as to which is dominant. Previous experimental and theoretical results for singly charged ion-Rydberg atom collisions demonstrate that direct capture processes dominate at intermediate collision speeds. We have found that for highly charged ion-Rydberg atom collisions electron capture via indirect velocity matching is dominant at intermediate collision speeds and contributes up to 90% of the total capture cross-section.

Journal of Physics B Atomic Molecular and Optical Physics•Jul 11, 2000•0 citations

Collision Dynamics of Rydberg Atoms and Molecules at Ultralow Energies

Flannery, M. R.

First Major Highlight: Collisional Stark Mixing at ultralow energies in Rydberg Plasmas. Atoms in high (n,l) states formed in cold Rydberg plasmas decay to the ground state in a succession of radiative transitions populating intermediate excited states. Which states are populated during cascading and with what probability can be obtained from known transition probabilities. Classical models simplify the calculation considerably, revealing the "trajectory" in nt space followed during the cascade, scaling rules and other aspects hidden within the quantal approach. Conserved Quantity (quantal analogue obscure): Quantal-Classical correspondence in radiative recombination and decay is directly demonstrated. Classical transition probabilities and radiative, recombination cross-section are in excellent agreement with quantal results. Cross section for three body collisional capture is formulated for arbitrary electron-energy distributions.

•Dec 31, 2005•0 citations
Electron capture by Cs+,{\mathrm{Cs}}^{+},Cs+, K+,{\mathrm{K}}^{+},K+, or Li+{\mathrm{Li}}^{+}Li+ from a Na\mathrm{Na}Na Rydberg target in an extreme Stark state of n=24,m=0n=24, m=0n=24,m=0 has been measured and compared with both a classical and a quantal calculation as a function of the reduced velocity v\ifmmode~\else˜\fi=0.15\ensuremath−1.6.\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.15\ensuremath{-}1.6.v\ifmmode~\else˜\fi=0.15\ensuremath−1.6. Peaks and shoulders are found at v\ifmmode~\else˜\fi=0.25,\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.25,v\ifmmode~\else˜\fi=0.25, 0.5, and 1.0 in the ratio of the measured capture cross sections for electronic charge polarization antiparallel and parallel to the ion-beam direction. A close-coupling calculation reveals similar features in the total capture cross sections near those same scaled velocities. A classical trajectory calculation attributes this structure to swapping of the electron between the two positive charge centers as they pass one another during the collision. The total classical capture cross section of a Rydberg atom having an upstream-directed charge distribution is shown to be the sum of five-and-greater-swap, three-swap, and one-swap contributions, which result in the structure near v\ifmmode~\else˜\fi=0.25,0.5,\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.25, 0.5,v\ifmmode~\else˜\fi=0.25,0.5, and 1.0, respectively.
A classical model of singly charged ion collisions with Rydberg atoms in linear Stark states directed toward the oncoming ion beam predicts a bimodal distribution of final states resulting from electron capture. At a reduced velocity $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}{=v}_{\mathrm{ion}}{/v}_{\mathrm{Bohr}}=0.45,$ the calculated energy distribution of captured electrons peaks near the target binding energy Ei,{E}_{i},Ei​, but has a second peak at energies roughly Ei/4.{E}_{i}/4.Ei​/4. Analysis of the impact-parameter dependence of the capture probabilities indicates that the second peak arises from three-swap capture events. The decrease in binding energy of the captured electrons is attributed to excitation via united-atom rotational coupling.
New experimental results have been obtained in collisions of singly charged ions with Na Rydberg atoms. (a) The distribution of final n states populated by electron capture shows non-monotonic variations of width with incident energy over the range 60-2100 eV. (b) The total capture cross section for alkali ions on Rydberg targets shows peaks and dips over the same energy range, correlated with particular reduced velocities v and the polarization of the exciting laser. (c) {ell}-Changing collision of Na{sup +} on Na(nd) targets, n=26 and 28, at low v preferentially transfer multiple units {h_bar} of orbital angular momentum under single-collision conditions, despite very large impact parameters. (d) Inelastic impacts of Na{sup f+} on Na 36s and 30p states, perturbed by electric fields, populate a strongly field-dependent mixture of nearby Stark levels. A synopsis of recent progress will be given.
Total electron capture by K+ or Cs+ from a Na Rydberg n=24 extremal Stark state, aligned with a weak external electric field, has been measured as a function of the angle between the atoms’ electric dipole moment and the projectile beam in the reduced-velocity range ṽ=0.15 to 1.05. A novel “Stark barrel” is described that produces the arbitrarily directed uniform electric field, smoothly switchable in both magnitude and direction in under 2 μs. The results illustrate the importance of spatial effects as opposed to velocity matching for a full understanding of electron capture near ṽ=1.
The classical trajectory Monte Carlo method has been used to simulate fully stripped ion-circular Rydberg atom collisions. We report that the mechanisms that govern the capture process for ions colliding with aligned Rydberg targets, namely direct and indirect velocity matching, alternate as to which is dominant. Previous experimental and theoretical results for singly charged ion-Rydberg atom collisions demonstrate that direct capture processes dominate at intermediate collision speeds. We have found that for highly charged ion-Rydberg atom collisions electron capture via indirect velocity matching is dominant at intermediate collision speeds and contributes up to 90% of the total capture cross-section.
First Major Highlight: Collisional Stark Mixing at ultralow energies in Rydberg Plasmas. Atoms in high (n,l) states formed in cold Rydberg plasmas decay to the ground state in a succession of radiative transitions populating intermediate excited states. Which states are populated during cascading and with what probability can be obtained from known transition probabilities. Classical models simplify the calculation considerably, revealing the "trajectory" in nt space followed during the cascade, scaling rules and other aspects hidden within the quantal approach. Conserved Quantity (quantal analogue obscure): Quantal-Classical correspondence in radiative recombination and decay is directly demonstrated. Classical transition probabilities and radiative, recombination cross-section are in excellent agreement with quantal results. Cross section for three body collisional capture is formulated for arbitrary electron-energy distributions.