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

Europhysics Letters (EPL)

Controlled formation of weakly bound atomic negative ions by electron transfer from state-selected Rydberg atoms

Monika Reicherts, T. Roth, A. Gopalan, M.‐W. Ruf, Hartmut Hotop, C. Desfrançois, I. I. Fabrikant

Published Oct 15, 1997• 26 citations
Publisher

Abstract

Using crossed atomic beams and mass spectrometric ion detection we have studied the formation of negative Ca ions in slow collisions between laser-excited state-selected Ne** ( ns , J = 2) and Ne** ( nd , J = 4) Rydberg atoms and ground state Ca atoms. The rate coefficients exhibit resonant behaviour with maxima at an effective principal quantum number n * of about 11.5 and an estimated peak value of about 10 −8 cm 3 s −1 . Two different theoretical calculations, based on a curve-crossing model and on a modified adiabatic theory, respectively, yield n *-dependences of the rate coefficients in good agreement with the experimental results.

DOI
10.1209/epl/i1997-00434-8

Related papers

Transfer of a weakly bound electron in collisions of Rydberg atoms with neutral particles. II. Ion-pair formation and resonant quenching of the Rb(nl) and Ne(nl) States by Ca, Sr, and Ba atoms

Alexander A. Narits, E. S. Mironchuk, Владимир Сергеевич Лебедев

Electron-transfer processes are studied in thermal collisions of Rydberg atoms with alkaline-earth Ca(4s 2), Sr(5s 2), and Ba(6s 2) atoms capable of forming negative ions with a weakly bound outermost p-electron. We consider the ion-pair formation and resonant quenching of highly excited atomic states caused by transitions between Rydberg covalent and ionic terms of a quasi-molecule produced in collisions of particles. The contributions of these reaction channels to the total depopulation cross section of Rydberg states of Rb(nl) and Ne(nl) atoms as functions of the principal quantum number n are compared for selectively excited nl-levels with l ≪ n and for states with large orbital quantum numbers l = n − 1, n − 2. It is shown that the contribution from resonant quenching dominates at small values of n, and the ion-pair formation process begins to dominate with increasing n. The values and positions of the maxima of cross sections for both processes strongly depend on the electron affinity of an alkaline-earth atom and on the orbital angular momentum l of a highly excited atom. It is shown that in the case of Rydberg atoms in states with large l ∼ n − 1, the rate constants of ion-pair formation and collisional quenching are considerably lower than those for nl-levels with l ≪ n.

Journal of Experimental and Theoretical Physics•Oct 1, 2013•4 citations

Formation of negative ions in collisions between Rydberg atoms and neutral particles

E. Yu. Buslov, B. A. Zon

We present a theoretical description of the formation of weakly bound (${E}_{b}\ensuremath{\sim}0.1\text{--}10$ meV) negative ions in collisions of Rydberg atoms with neutral atoms or molecules. Using the adiabatic approximation for the collision, we obtain an analytical expression for the formation cross section. It is shown that the cross section has a sharp peak in its dependence on the principal quantum number of the Rydberg electron. This result is in agreement with the experimental studies. We obtain a simple analytical expression that relates the peak position and the binding energy of the negative ion. This expression generalizes the empirical law previously established by Desfran\ifmmode \mbox{\c{c}}\else \c{c}\fi{}ois [Phys. Rev. A 51, 3667 (1995)]. Comparison of our calculations with the experimental data on dipole-bound anion formation shows that the obtained formula can be used for determination of binding energies of weakly bound negative ions from Rydberg electron transfer reactions with good accuracy.

Physical Review A•Apr 10, 2012•17 citations

Formation of ions by charge transfer from Rydberg atoms

I. I. Fabrikant

A simple model potential for the electron-Ca-atom interaction is used to describe the process of charge transfer in Rydberg-atom-calcium-atom collisions. The interaction of the final ionic state with degenerate manifolds of Rydberg covalent states is treated by inclusion of the negative ion decay due to the Coulomb field of the positive ion. This effect leads to a strong reduction of the charge transfer cross section and shifting of the value of the principal quantum number n corresponding to the cross section maximum towards higher n . The rates averaged over the experimental velocity distribution agree quite well with the experimental data and with independent calculations using the Landau-Zener model, although the results of the latter are higher than the present for the charge transfer from s states. The distortion of the classical ion trajectories due to the Coulomb interaction plays a minor role in the calculation of the negative-ion decay probability.

Journal of Physics B Atomic Molecular and Optical Physics•Jul 14, 1998•24 citations

Evidence for resonant formation of Ca− in collisions of Rydberg and ground-state Ca atoms

K. W. McLaughlin, D. W. Duquette

Relative yields of ${\mathrm{Ca}}^{+}$ and ${\mathrm{Ca}}^{\mathrm{\ensuremath{-}}}$ ions from thermal-energy collisions between highly excited ${\mathrm{Ca}}^{\mathrm{*}}$ 4snd $^{1}$D Rydberg atoms and Ca ground-state atoms are measured as a function of n. The collisions take place within an effusive Ca atomic beam. The cross section for a collision resulting in a bound ${\mathrm{Ca}}^{\mathrm{\ensuremath{-}}}$ and a ground-state ${\mathrm{Ca}}^{+}$ is expected to be large when the binding energy of the excited Rydberg state nearly matches the electron affinity of Ca. We observe a large increase in positive and negative ions for n=25 only. This result strongly suggests that the binding energy of ${\mathrm{Ca}}^{\mathrm{\ensuremath{-}}}$ is 24\ifmmode\pm\else\textpm\fi{}1.4 meV.

Physical Review Letters•Feb 21, 1994•35 citations

Close-coupling calculations of Ca− formation by charge transfer from Rydberg atoms

I. I. Fabrikant, M. I. Chibisov

We formulate the semiclassical close-coupling method for a theoretical description of ion-pair formation in Rydberg-atom--ground-state-atom collisions at thermal energies and apply it to the process $\mathrm{Ca}{(4s}^{2})+{\mathrm{Ne}}^{*}(n)\ensuremath{\rightarrow}{\mathrm{Ca}}^{\ensuremath{-}}{(4s}^{2}4p)+{\mathrm{Ne}}^{+}.$ Our results for the formation of an isolated negative-ion state are very close to those obtained previously using the decay model, although the results for S states are somewhat higher, since the decay model underestimates the survival probability for the ion pair. After the inclusion in our close-coupling calculations of the two fine-structure components of ${\mathrm{Ca}}^{\ensuremath{-}},$ we find that the cross section increases substantially (by about a factor of 2) because of correlation between probabilities for population of two fine-structure sublevels.

Physical Review A•Jan 14, 2000•18 citations

Comparative studies of ion-pair formation and resonant quenching processes in collisions of Rydberg atoms with the alkaline-earth atoms

Alexander A. Narits, E. S. Mironchuk, Владимир Сергеевич Лебедев

We report the results of comparative studies of ion-pair formation and quenching processes in collisions of Rydberg Li( nl ) and Cs( nl ) atoms with Ca(4s 2 ), Sr(5s 2 ) and Ba(6s 2 ) atoms possessing small electron affinities. Our consideration includes both the cases of selectively excited Rydberg nl -states with small orbital angular momentum ( l ≪ n ) and nearly circular states with l ∼ n − 1. Calculations of the electron-transfer processes are based on the semiclassical theory of nonadiabatic transitions and exact expression for the Rydberg-covalent–ionic coupling terms. Calculations of nonresonant quenching processes are carried out within the framework of the available theory of inelastic and quasielastic transitions between Rydberg-covalent states. The ion-pair formation and resonant quenching cross sections are shown to be significantly dependent not only on the principal quantum number n but also on the orbital angular momentum l and the binding energy of the alkaline-earth anion. For each system under study we find the regions of n in which either the resonant quenching or the ion-pair formation processes are predominant. The relative role of the resonant and nonresonant mechanisms of depopulation of Rydberg states is investigated.

Journal of Physics B Atomic Molecular and Optical Physics•Dec 17, 2013•13 citations
Using crossed atomic beams and mass spectrometric ion detection we have studied the formation of negative Ca ions in slow collisions between laser-excited state-selected Ne** ( ns , J = 2) and Ne** ( nd , J = 4) Rydberg atoms and ground state Ca atoms. The rate coefficients exhibit resonant behaviour with maxima at an effective principal quantum number n * of about 11.5 and an estimated peak value of about 10 −8 cm 3 s −1 . Two different theoretical calculations, based on a curve-crossing model and on a modified adiabatic theory, respectively, yield n *-dependences of the rate coefficients in good agreement with the experimental results.
Electron-transfer processes are studied in thermal collisions of Rydberg atoms with alkaline-earth Ca(4s 2), Sr(5s 2), and Ba(6s 2) atoms capable of forming negative ions with a weakly bound outermost p-electron. We consider the ion-pair formation and resonant quenching of highly excited atomic states caused by transitions between Rydberg covalent and ionic terms of a quasi-molecule produced in collisions of particles. The contributions of these reaction channels to the total depopulation cross section of Rydberg states of Rb(nl) and Ne(nl) atoms as functions of the principal quantum number n are compared for selectively excited nl-levels with l ≪ n and for states with large orbital quantum numbers l = n − 1, n − 2. It is shown that the contribution from resonant quenching dominates at small values of n, and the ion-pair formation process begins to dominate with increasing n. The values and positions of the maxima of cross sections for both processes strongly depend on the electron affinity of an alkaline-earth atom and on the orbital angular momentum l of a highly excited atom. It is shown that in the case of Rydberg atoms in states with large l ∼ n − 1, the rate constants of ion-pair formation and collisional quenching are considerably lower than those for nl-levels with l ≪ n.
We present a theoretical description of the formation of weakly bound (${E}_{b}\ensuremath{\sim}0.1\text{--}10$ meV) negative ions in collisions of Rydberg atoms with neutral atoms or molecules. Using the adiabatic approximation for the collision, we obtain an analytical expression for the formation cross section. It is shown that the cross section has a sharp peak in its dependence on the principal quantum number of the Rydberg electron. This result is in agreement with the experimental studies. We obtain a simple analytical expression that relates the peak position and the binding energy of the negative ion. This expression generalizes the empirical law previously established by Desfran\ifmmode \mbox{\c{c}}\else \c{c}\fi{}ois [Phys. Rev. A 51, 3667 (1995)]. Comparison of our calculations with the experimental data on dipole-bound anion formation shows that the obtained formula can be used for determination of binding energies of weakly bound negative ions from Rydberg electron transfer reactions with good accuracy.
A simple model potential for the electron-Ca-atom interaction is used to describe the process of charge transfer in Rydberg-atom-calcium-atom collisions. The interaction of the final ionic state with degenerate manifolds of Rydberg covalent states is treated by inclusion of the negative ion decay due to the Coulomb field of the positive ion. This effect leads to a strong reduction of the charge transfer cross section and shifting of the value of the principal quantum number n corresponding to the cross section maximum towards higher n . The rates averaged over the experimental velocity distribution agree quite well with the experimental data and with independent calculations using the Landau-Zener model, although the results of the latter are higher than the present for the charge transfer from s states. The distortion of the classical ion trajectories due to the Coulomb interaction plays a minor role in the calculation of the negative-ion decay probability.
Relative yields of Ca+{\mathrm{Ca}}^{+}Ca+ and ${\mathrm{Ca}}^{\mathrm{\ensuremath{-}}}$ ions from thermal-energy collisions between highly excited Ca∗{\mathrm{Ca}}^{\mathrm{*}}Ca∗ 4snd 1^{1}1D Rydberg atoms and Ca ground-state atoms are measured as a function of n. The collisions take place within an effusive Ca atomic beam. The cross section for a collision resulting in a bound ${\mathrm{Ca}}^{\mathrm{\ensuremath{-}}}$ and a ground-state Ca+{\mathrm{Ca}}^{+}Ca+ is expected to be large when the binding energy of the excited Rydberg state nearly matches the electron affinity of Ca. We observe a large increase in positive and negative ions for n=25 only. This result strongly suggests that the binding energy of ${\mathrm{Ca}}^{\mathrm{\ensuremath{-}}}$ is 24\ifmmode\pm\else\textpm\fi{}1.4 meV.
We formulate the semiclassical close-coupling method for a theoretical description of ion-pair formation in Rydberg-atom--ground-state-atom collisions at thermal energies and apply it to the process $\mathrm{Ca}{(4s}^{2})+{\mathrm{Ne}}^{*}(n)\ensuremath{\rightarrow}{\mathrm{Ca}}^{\ensuremath{-}}{(4s}^{2}4p)+{\mathrm{Ne}}^{+}.$ Our results for the formation of an isolated negative-ion state are very close to those obtained previously using the decay model, although the results for S states are somewhat higher, since the decay model underestimates the survival probability for the ion pair. After the inclusion in our close-coupling calculations of the two fine-structure components of ${\mathrm{Ca}}^{\ensuremath{-}},$ we find that the cross section increases substantially (by about a factor of 2) because of correlation between probabilities for population of two fine-structure sublevels.
We report the results of comparative studies of ion-pair formation and quenching processes in collisions of Rydberg Li( nl ) and Cs( nl ) atoms with Ca(4s 2 ), Sr(5s 2 ) and Ba(6s 2 ) atoms possessing small electron affinities. Our consideration includes both the cases of selectively excited Rydberg nl -states with small orbital angular momentum ( l ≪ n ) and nearly circular states with l ∼ n − 1. Calculations of the electron-transfer processes are based on the semiclassical theory of nonadiabatic transitions and exact expression for the Rydberg-covalent–ionic coupling terms. Calculations of nonresonant quenching processes are carried out within the framework of the available theory of inelastic and quasielastic transitions between Rydberg-covalent states. The ion-pair formation and resonant quenching cross sections are shown to be significantly dependent not only on the principal quantum number n but also on the orbital angular momentum l and the binding energy of the alkaline-earth anion. For each system under study we find the regions of n in which either the resonant quenching or the ion-pair formation processes are predominant. The relative role of the resonant and nonresonant mechanisms of depopulation of Rydberg states is investigated.