Physical Review A

Experimental evidence for negative-ion formation by the collisional reaction Rb(6d)+Rb(5s)→Rb++Rb−

M. Chéret, L. Barbier

Published Aug 1, 1984• 10 citations

Abstract

Negative ions are observed in a rubidium vapor when atoms are excited to the $6d$ level. Analysis shows that they correspond to the collision $\mathrm{Rb}(6d^{2}D_{\frac{5}{2}})+\mathrm{Rb}(5s)+\ensuremath{\Delta}E\ensuremath{\rightarrow}{\mathrm{Rb}}^{+}+{\mathrm{Rb}}^{\ensuremath{-}}$. The rate coefficient of the process is found to be (1.1\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\ensuremath{-}1}$ and the corresponding cross section 1.3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$.

DOI: 10.1103/physreva.30.1132

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Physical Review A

Experimental evidence for negative-ion formation by the collisional reaction Rb(6d)+Rb(5s)→Rb++Rb−

M. Chéret, L. Barbier

Published Aug 1, 1984• 10 citations

Publisher

Abstract

Negative ions are observed in a rubidium vapor when atoms are excited to the

6d

level. Analysis shows that they correspond to the collision

\mathrm{Rb}(6d^{2}D_{\frac{5}{2}})+\mathrm{Rb}(5s)+\ensuremath{\Delta}E\ensuremath{\rightarrow}{\mathrm{Rb}}^{+}+{\mathrm{Rb}}^{\ensuremath{-}}

. The rate coefficient of the process is found to be (1.1\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}

{10}^{\ensuremath{-}12}

{\mathrm{cm}}^{3}

{\mathrm{s}}^{\ensuremath{-}1}

and the corresponding cross section 1.3\ifmmode\times\else\texttimes\fi{}

{10}^{\ensuremath{-}16}

{\mathrm{cm}}^{2}

DOI: 10.1103/physreva.30.1132

Related papers

COLLISIONAL IONISATION OF EXCITED RUBIDIUM ATOMS

M. Chéret, L. Barbier

Le Journal de Physique ColloquesJan 1, 19852 citations

Measured Absolute Cross Sections for K* + Rb Collisional Excitation Transfer

Michael H. Ornstein, Richard N. Zare

The electronic excitation transfer processes, $\mathrm{K}(^{2}P_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{Rb}(^{2}S_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{K}(^{2}S_{\frac{1}{2}})+\mathrm{Rb}(^{2}P_{\frac{1}{2}})+\ensuremath{\Delta}E$ and $\mathrm{K}(^{2}P_{\frac{3}{2}})+\mathrm{Rb}(^{2}S_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{K}(^{2}S_{\frac{1}{2}})+\mathrm{Rb}(^{2}P_{\frac{1}{2}})+\ensuremath{\Delta}E$ have been studied by irradiating a cell containing a nonequilibrium mixture of potassium and rubidium vapors with either the 7665 \AA{} D2 line or the 7699 \AA{} D1 line of the potassium resonance doublet. The resulting collisionally induced rubidium 7948 \AA{} fluorescence signal, isolated by interference filters used in tandem, is detected with a liquid-nitrogen-cooled $S\ensuremath{-}1$ photo-multiplier placed at right angles to the direction of excitation. Measurements of the intensity ratio of the potassium and rubidium fluoresence combined with an optical absorption determination of the rubidium atom density yields the following excitation transfer cross sections: $Q[\mathrm{K}(^{2}P_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{Rb}(^{2}P_{\frac{1}{2}})]=2.2 {\AA{}}^{2}\ifmmode\pm\else\textpm\fi{}25%$ and $Q[\mathrm{K}(^{2}P_{\frac{3}{2}})\ensuremath{\rightarrow}\mathrm{Rb}(^{2}P_{\frac{1}{2}})]=2.6 {\AA{}}^{2}\ifmmode\pm\else\textpm\fi{}20%$ at $T=365\ifmmode^\circ\else\textdegree\fi{}\mathrm{K}\ifmmode\pm\else\textpm\fi{}2%$. Throughout an experimental run the potassium and rubidium vapor pressures are varied, but data are taken for only the lowest vapor pressures for which corrections due to resonance radiation imprisonment are unnecessary.The electronic excitation transfer processes, $\mathrm{K}(^{2}P_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{Rb}(^{2}S_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{K}(^{2}S_{\frac{1}{2}})+\mathrm{Rb}(^{2}P_{\frac{1}{2}})+\ensuremath{\Delta}E$ and $\mathrm{K}(^{2}P_{\frac{3}{2}})+\mathrm{Rb}(^{2}S_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{K}(^{2}S_{\frac{1}{2}})+\mathrm{Rb}(^{2}P_{\frac{1}{2}})+\ensuremath{\Delta}E$ have been studied by irradiating a cell containing a nonequilibrium mixture of potassium and rubidium vapors with either the 7665 \AA{} D2 line or the 7699 \AA{} D1 line of the potassium resonance doublet. The resulting collisionally induced rubidium 7948 \AA{} fluorescence signal, isolated by interference filters used in tandem, is detected with a liquid-nitrogen-cooled $S\ensuremath{-}1$ photo-multiplier placed at right angles to the direction of excitation. Measurements of the intensity ratio of the potassium and rubidium fluoresence combined with an optical absorption determination of the rubidium atom density yields the following excitation transfer cross sections: $Q[\mathrm{K}(^{2}P_{\frac{1}{2}})\ensuremath{\rightarrow}\mathrm{Rb}(^{2}P_{\frac{1}{2}})]=2.2 {\AA{}}^{2}\ifmmode\pm\else\textpm\fi{}25%$ and $Q[\mathrm{K}(^{2}P_{\frac{3}{2}})\ensuremath{\rightarrow}\mathrm{Rb}(^{2}P_{\frac{1}{2}})]=2.6 {\AA{}}^{2}\ifmmode\pm\else\textpm\fi{}20%$ at $T=365\ifmmode^\circ\else\textdegree\fi{}\mathrm{K}\ifmmode\pm\else\textpm\fi{}2%$. Throughout an experimental run the potassium and rubidium vapor pressures are varied, but data are taken for only the lowest vapor pressures for which corrections due to resonance radiation imprisonment are unnecessary.

Physical ReviewMay 5, 196917 citations

Experimental study of Penning and Hornbeck-Molnar ionisation of rubidium atoms excited in a high s or d level (5d⩽nl⩽11s)

L. Barbier, M. Chéret

Rb + and Rb 2 + formation in a laser-excited Rb vapour is extensively studied for s and d levels ranging from 5d to 11s levels. Collisional ionisation with a ground-state atom leads to Rb 2 + formation by Hornbeck-Molnar reaction with rate coefficients lying in the 10 -10 cm 3 s -1 range. This reaction is analysed theoretically. Penning ionisation occurs in collision with a resonant-state atom, Rb(5p), with a high efficiency (rate coefficient above 10 -8 cm 3 s -1 ). Associative ionisation between the 7s level and the 5p level is also observed (rate coefficient about 10 -10 cm 3 s -1 ). This reaction appears negligible for the neighbouring 5d level.Rb + and Rb 2 + formation in a laser-excited Rb vapour is extensively studied for s and d levels ranging from 5d to 11s levels. Collisional ionisation with a ground-state atom leads to Rb 2 + formation by Hornbeck-Molnar reaction with rate coefficients lying in the 10 -10 cm 3 s -1 range. This reaction is analysed theoretically. Penning ionisation occurs in collision with a resonant-state atom, Rb(5p), with a high efficiency (rate coefficient above 10 -8 cm 3 s -1 ). Associative ionisation between the 7s level and the 5p level is also observed (rate coefficient about 10 -10 cm 3 s -1 ). This reaction appears negligible for the neighbouring 5d level.

Journal of Physics B Atomic and Molecular PhysicsMar 26, 198761 citations

Ion formation in collisions of Rb(8s) with Rb(5p) and Rb(5s)

M. Chéret, W. Lindinger, L. Barbier +1 more

Chemical Physics LettersApr 1, 198210 citations

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.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 PhysicsOct 1, 20134 citations

Formation rate for Rb ${}_2^+$ molecular ions created in collisions of Rb Rydberg and ground-state atomsFormation rate for Rb${}_2^+$ molecular ions created in collisions of Rb Rydberg and ground-state atoms

Jovica Stanojevic, Robin C ot 'e

Bulletin of the American Physical SocietyMay 27, 20160 citations

Negative ions are observed in a rubidium vapor when atoms are excited to the

6d

level. Analysis shows that they correspond to the collision

\mathrm{Rb}(6d^{2}D_{\frac{5}{2}})+\mathrm{Rb}(5s)+\ensuremath{\Delta}E\ensuremath{\rightarrow}{\mathrm{Rb}}^{+}+{\mathrm{Rb}}^{\ensuremath{-}}

. The rate coefficient of the process is found to be (1.1\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}

{10}^{\ensuremath{-}12}

{\mathrm{cm}}^{3}

{\mathrm{s}}^{\ensuremath{-}1}

and the corresponding cross section 1.3\ifmmode\times\else\texttimes\fi{}

{10}^{\ensuremath{-}16}

{\mathrm{cm}}^{2}

Formation rate for Rb

{}_2^+

molecular ions created in collisions of Rb Rydberg and ground-state atoms