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

Collision-Induced Dipole Moments.

Thomas F. Gallagher

Published Oct 1, 1984• 0 citations
OpenAlex

Abstract

Experimental studies of collision induced absorption of forbidden transitions have been conducted on Cs(6s sub 1 /2 - 5d sub 5/2), Na (nd sub 3/2 - nf sub 5/2) and Na (nd sub 3/2 - ng sub 7/2), n is greater than or = to 15. Perturbers utilized include heavy rare gases, molecular dipoles, and positive ions. A very strong enhancement of the forbidden Rydberg transitions in Na was observed and attributed to ionic space charge.

Related papers

Observation of collision-induced 6s–ns transitions in the absorption spectrum of cesium in the presence of xenon

M. A. Dakhil, John F. Kielkopf

The forbidden transitions of the types 6s–ns have been observed in the absorption spectrum of cesium perturbed by xenon foreign gas for n = 11 to n = 19. The new observed levels agree with an extrapolation of previously known ns levels. These transitions appears to be induced by collisions with xenon perturbers.

Journal of the Optical Society of America•Jun 1, 1977•7 citations

Onset of dipole-allowed transitions in inelastic collisions of charged particles with Na(30s) Rydberg atoms

R G Rolfes, Victor D. Irby, Oleg P. Makarov +2 more

An experimental study of the depopulation of Na(30s) Rydberg atoms under He + ion bombardment has been undertaken to identify the range of collision velocities at which strongly coupled behaviour of the 30s and nearby levels at low velocity changes to predominantly dipole-allowed coupled at high velocity. Ion energies ranged from 700 to 3900 eV corresponding to collision velocities of 2.4 to 5.6 times the mean orbital speed of the excited 30s electron. The ratio of the cross section for the dipole-allowed transitions (30s to 30p and 30s to 29p) to the total depopulation cross section was determined for each collision velocity. (Other dipole-allowed transitions were observed to be negligible.) This ratio was found to increase from only 20% at a reduced velocity of 2.4 to 65% at a reduced velocity of 5.6. The ratio of the two dipole cross sections, sigma (30s-30p)/ sigma (30s-29p), was also determined and compared to calculations based on the dipole approximation with first-order perturbation theory.

Journal of Physics B Atomic Molecular and Optical Physics•Mar 28, 1994•5 citations

Collision-induced absorption in atomic electronic transitions

Alan C. Gallagher, Theodore D. Holstein

The collision-induced absorption and emission coefficients for electric-dipole forbidden atomic transitions are calculated for weak radiation fields. The approximations used are valid for $\ensuremath{\hbar}\ensuremath{\omega}$ near $\ensuremath{\hbar}{\ensuremath{\omega}}_{0}$, the atomic energy differences. The example case of $S\ensuremath{-}D$ transitions induced by a spherically symmetric perturber (e.g., a noble-gas atom) is treated in detail and compared to measurements. The case of "radiative collisions," in which both colliding atoms change their state, is included in the theory and is also compared to experiment.

Physical Review A•Dec 1, 1977•125 citations

Dipole-allowed and dipole-forbiddenlchange in slow collisions of Na+ with Na(28d) Rydberg atoms

Keith B. MacAdam, R G Rolfes, Xufei Sun +3 more

Both dipole-allowed and dipole-forbidden transitions occur in slow l-change collisions of ${\mathrm{Na}}^{+}$ with Na(28d) Rydberg atoms, despite the validity of the dipole approximation. Measurements of the velocity dependence of the final-state distribution under single-collision conditions are reported. Effects of strong coupling were found, in partial agreement with recent coupled-channel calculations. Microwave-resonance techniques were used to identify the selective-field-ionization signatures of 28f, g, and h states.

Physical Review A•Nov 1, 1987•18 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

Level broadening cross sections for nP1/2Rydberg states of Na, K and Rb atoms

Leszek Sirko, K. Rosiński

The impact broadening of Na(nP1/2) (n=6-24), K(nP1/2) (n=8-24) and Rb(nP12/) (n=10-24) levels by noble-gas atoms, N2 molecules and alkali atoms in the ground state has been investigated. Broadening cross sections have been evaluated on the grounds of contributions coming from Rydberg-electron-perturber and ionic core-perturber scattering. Broadening cross sections for Cs(nD3/2)+Cs(6S) collisions for n=11-23 have also been calculated to compare with the experimental ones. Theoretically evaluated broadening cross sections for K(nP12/)+K(4S) and Cs(nD3/2)+Cs(6S) collisions appeared to be in good agreement with existing experimental data.

Journal of Physics B Atomic Molecular and Optical Physics•Jul 28, 1988•0 citations
Experimental studies of collision induced absorption of forbidden transitions have been conducted on Cs(6s sub 1 /2 - 5d sub 5/2), Na (nd sub 3/2 - nf sub 5/2) and Na (nd sub 3/2 - ng sub 7/2), n is greater than or = to 15. Perturbers utilized include heavy rare gases, molecular dipoles, and positive ions. A very strong enhancement of the forbidden Rydberg transitions in Na was observed and attributed to ionic space charge.
An experimental study of the depopulation of Na(30s) Rydberg atoms under He + ion bombardment has been undertaken to identify the range of collision velocities at which strongly coupled behaviour of the 30s and nearby levels at low velocity changes to predominantly dipole-allowed coupled at high velocity. Ion energies ranged from 700 to 3900 eV corresponding to collision velocities of 2.4 to 5.6 times the mean orbital speed of the excited 30s electron. The ratio of the cross section for the dipole-allowed transitions (30s to 30p and 30s to 29p) to the total depopulation cross section was determined for each collision velocity. (Other dipole-allowed transitions were observed to be negligible.) This ratio was found to increase from only 20% at a reduced velocity of 2.4 to 65% at a reduced velocity of 5.6. The ratio of the two dipole cross sections, sigma (30s-30p)/ sigma (30s-29p), was also determined and compared to calculations based on the dipole approximation with first-order perturbation theory.
The collision-induced absorption and emission coefficients for electric-dipole forbidden atomic transitions are calculated for weak radiation fields. The approximations used are valid for $\ensuremath{\hbar}\ensuremath{\omega}$ near $\ensuremath{\hbar}{\ensuremath{\omega}}_{0}$, the atomic energy differences. The example case of $S\ensuremath{-}D$ transitions induced by a spherically symmetric perturber (e.g., a noble-gas atom) is treated in detail and compared to measurements. The case of "radiative collisions," in which both colliding atoms change their state, is included in the theory and is also compared to experiment.
Both dipole-allowed and dipole-forbidden transitions occur in slow l-change collisions of Na+{\mathrm{Na}}^{+}Na+ with Na(28d) Rydberg atoms, despite the validity of the dipole approximation. Measurements of the velocity dependence of the final-state distribution under single-collision conditions are reported. Effects of strong coupling were found, in partial agreement with recent coupled-channel calculations. Microwave-resonance techniques were used to identify the selective-field-ionization signatures of 28f, g, and h states.
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.
The impact broadening of Na(nP1/2) (n=6-24), K(nP1/2) (n=8-24) and Rb(nP12/) (n=10-24) levels by noble-gas atoms, N2 molecules and alkali atoms in the ground state has been investigated. Broadening cross sections have been evaluated on the grounds of contributions coming from Rydberg-electron-perturber and ionic core-perturber scattering. Broadening cross sections for Cs(nD3/2)+Cs(6S) collisions for n=11-23 have also been calculated to compare with the experimental ones. Theoretically evaluated broadening cross sections for K(nP12/)+K(4S) and Cs(nD3/2)+Cs(6S) collisions appeared to be in good agreement with existing experimental data.