Journal of Physics B Atomic and Molecular Physics

Collisional depopulation cross sections of high-Rydberg Na s states by Ar

Jacques Boulmer, J. F. Delpech, J. C. Gauthier, Kambiz Ali Safinya

Published Dec 14, 1981• 11 citations

Abstract

Na (ns)-Ar collisions have been investigated for 20<or=n<or=48 using a beam-pulsed cell technique with time-resolved selective field ionisation. The total cross section has a broad maximum of 130 AA 2 around n=30-35. Preliminary observations indicate that principal quantum number changes are large in such collisions.

DOI: 10.1088/0022-3700/14/23/018

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Journal of Physics B Atomic and Molecular Physics

Collisional depopulation cross sections of high-Rydberg Na s states by Ar

Jacques Boulmer, J. F. Delpech, J. C. Gauthier, Kambiz Ali Safinya

Published Dec 14, 1981• 11 citations

Publisher

Abstract

DOI: 10.1088/0022-3700/14/23/018

Related papers

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Journal of Physics B Atomic and Molecular PhysicsNov 14, 198111 citations

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Thermal-energy collisions of rubidium Rydberg states with N2 molecules

L. Petitjean, F. Gounand, P. R. Fournier

The total depopulation cross sections by ${\mathrm{N}}_{2}$ of high rubidium Rydberg states, $\mathrm{Rb}(\mathrm{ns}) (n=25\ensuremath{-}46)$ and $\mathrm{Rb}(\mathrm{nd}) (n=23\ensuremath{-}44)$, have been measured using time-resolved field ionization technique and compared to previous results obtained on the quenching of $\mathrm{Rb}(\mathrm{nl})$ by CO. It is shown that the $\mathrm{Rb}(\mathrm{nl})$ depopulation by ${\mathrm{N}}_{2}$ is much less efficient than the $\mathrm{Rb}(\mathrm{nl})$ depopulation by CO and leads mainly to the quasielastic process of angular momentum mixing via the short-range interaction between the quasifree Rydberg-state electron and the molecule. It is clearly demonstrated that the presence of a permanent dipole in CO changes the collisional processes drastically. The agreement between experimental and theoretical predictions based on the impulse approximation is quite satisfactory.The total depopulation cross sections by ${\mathrm{N}}_{2}$ of high rubidium Rydberg states, $\mathrm{Rb}(\mathrm{ns}) (n=25\ensuremath{-}46)$ and $\mathrm{Rb}(\mathrm{nd}) (n=23\ensuremath{-}44)$, have been measured using time-resolved field ionization technique and compared to previous results obtained on the quenching of $\mathrm{Rb}(\mathrm{nl})$ by CO. It is shown that the $\mathrm{Rb}(\mathrm{nl})$ depopulation by ${\mathrm{N}}_{2}$ is much less efficient than the $\mathrm{Rb}(\mathrm{nl})$ depopulation by CO and leads mainly to the quasielastic process of angular momentum mixing via the short-range interaction between the quasifree Rydberg-state electron and the molecule. It is clearly demonstrated that the presence of a permanent dipole in CO changes the collisional processes drastically. The agreement between experimental and theoretical predictions based on the impulse approximation is quite satisfactory.

Physical Review AAug 1, 198423 citations

We have measured total cross sections for the collisional depopulation of high-lying

\mathrm{nP}

states ($12\ensuremath{\le}n\ensuremath{\le}22$) of rubidium induced by thermal collisions with ground-state rubidium or rare-gas atoms. It is observed that for $n\ensuremath{\ge}14$ the rubidium-rare-gas cross sections do not vary with the principal quantum number, contrary to previous hypotheses. Our results are discussed using the simple argument of quasifree behavior of the valence electron involving either an elastic-scattering or a binary-encounter approach. However, the disagreement observed between the experimental and the computed cross sections suggests that a three-body approach is generally needed for a good understanding of collisional processes involving highly excited states.

In thermal-energy collisions between sodium atoms in

\mathrm{ns}

\mathrm{np}

states (

32<~n<~52

) and xenon atoms, depopulation of the Rydberg states is observed to occur predominantly through state-changing reactions of the type $\mathrm{Na}(ns or np)+\mathrm{Xe}\ensuremath{\rightarrow}\mathrm{Na}(n\ensuremath{-}1, l>~2)+\mathrm{Xe}$. For the present range of

n

, the measured cross sections increase with

n

and lie between 1500 and 2600

{\mathrm{\AA{}}}^{2}

for

\mathrm{ns}

states and between 2000 and 4200

{\mathrm{\AA{}}}^{2}

for

\mathrm{np}

states. Implications of the data are discussed.

The total depopulation cross sections by

{\mathrm{N}}_{2}

of high rubidium Rydberg states, $\mathrm{Rb}(\mathrm{ns}) (n=25\ensuremath{-}46)$ and $\mathrm{Rb}(\mathrm{nd}) (n=23\ensuremath{-}44)$, have been measured using time-resolved field ionization technique and compared to previous results obtained on the quenching of

\mathrm{Rb}(\mathrm{nl})

by CO. It is shown that the

\mathrm{Rb}(\mathrm{nl})

depopulation by

{\mathrm{N}}_{2}

is much less efficient than the

\mathrm{Rb}(\mathrm{nl})

depopulation by CO and leads mainly to the quasielastic process of angular momentum mixing via the short-range interaction between the quasifree Rydberg-state electron and the molecule. It is clearly demonstrated that the presence of a permanent dipole in CO changes the collisional processes drastically. The agreement between experimental and theoretical predictions based on the impulse approximation is quite satisfactory.