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

Journal of Physics B Atomic and Molecular Physics

Comparison of collisional redistribution and emission line shapes

Michael G. Raymer, John L. Carlsten, Goran Pichler

Published Feb 28, 1979• 24 citations
Publisher

Abstract

The authors have studied collisional redistribution of near-resonance radiation in thallium vapour caused by collisions with argon buffer gas. Electronic Raman scattering and collision-induced fluorescence were spectrally resolved, both to the weakly populated metastable 6 2 P 3/2 level in thallium. Thus the problem with radiative trapping encountered in previous experiments is partially avoided. By measuring the total collision-induced fluorescence as a function of the incident laser frequency, the absolute collisional redistribution line shape is obtained.

DOI
10.1088/0022-3700/12/4/001

Related papers

Simultaneous Observations of Stimulated Raman Scattering and Stimulated Collision-Induced Fluorescence

Michael G. Raymer, John L. Carlsten

We have observed collisional redistribution of laser light scattered by a three-level atom, thallium, in the presence of argon. The two observed spectral components correspond to Raman scattering and collision-induced fluorescence. We have seen the growth of both components from spontaneous to stimulated scattering as the laser intensity is increased. While the gain for the Raman component agrees with theory, the observed gain of the collision-induced fluorescence is over an order of magnitude lower than predicted.

Physical Review Letters•Nov 21, 1977•39 citations

Collisional redistribution and saturation of near-resonance scattered light

John L. Carlsten, A. Szöke, Michael G. Raymer

This paper reports on our studies of near-resonant scattering of laser light in a collisional environment. A pulsed dye laser with a peak power of 55 MW/${\mathrm{cm}}^{2}$ was tuned near the 460.73-nm resonance line of strontium and the side emission was observed from an oven containing both strontium vapor and argon buffer gas. The emission was composed of three spectral components: Rayleigh scattering at the frequency of the laser ${\ensuremath{\omega}}_{L}$, fluorescence at the resonance frequency ${\ensuremath{\omega}}_{0}$ of strontium, and a third component at $2{\ensuremath{\omega}}_{L}\ensuremath{-}{\ensuremath{\omega}}_{0}$. These three components have been studied as a function of the frequency and intensity of the laser and also as a function of the argon buffer gas pressure. While the Rayleigh emission was found to vary as ${\ensuremath{\Delta}}^{\ensuremath{-}2}$ ($\ensuremath{\Delta}={\ensuremath{\omega}}_{0}\ensuremath{-}{\ensuremath{\omega}}_{L}$), the fluorescence component, which was produced by Sr-Ar collisions, was found to be asymmetric with the sign of $\ensuremath{\Delta}$ as predicted by line-broadening theory. By measuring the ratio of the intensities of the fluorescence and Rayleigh components, we were able to measure directly the collisional redistribution function, important in the study of radiative transfer in stellar and planetary atmospheres. At high laser intensities all three components were found to saturate. The results were compared with the theoretical predictions of Mollow's steady-state theory. Theoretical fits for the high-intensity results were obtained when the collisional cross sections were taken to be considerably smaller than in our low-intensity measurements. We believe the discrepancy lies in the use of a steady-state theory for a transient experiment. Effects of radiative trapping and spatial averaging are also discussed.

Physical Review A•Mar 1, 1977•233 citations

Tunable dye laser spectroscopy of atomic calcium: collisional redistribution of radiation

Alan Corney, J V M McGinley

By tuning a pulsed dye laser through the resonance line of calcium at 422.7 nm the authors have investigated the spectral redistribution of laser radiation by calcium vapour. Two main components were resolved in the side emission from an oven containing calcium vapour and argon buffer gas. These are produced by Rayleigh scattering and by collision-induced fluorescence. The intensity of the Rayleigh component was found to vary as Delta -2 where Delta = omega 21 - omega L is the laser detuning from resonance. In contrast the intensity of the collision-induced fluorescence showed a markedly asymmetric dependence on detuning. Detailed studies of the collision-induced fluorescence have enabled the complete line shape of the calcium resonance line perturbed by argon to be determined. The interpretation of this data in terms of a frequency-dependent collision rate, gamma E ( Delta ), is discussed. This paper also reports calculations of theoretical line profiles using the unified Franck-Condon theory and trial interatomic difference potentials. The comparison of the experimental and theoretical line profiles enables the range of validity of the unified Franck-Condon theory to be assessed and the form of the optimum Ca-Ar difference potential to be selected.

Journal of Physics B Atomic and Molecular Physics•Sep 14, 1981•27 citations

Collisional redistribution of near-resonant scattered light in Sr vapour

John L. Carlsten, A. Szöke

Strontium vapour was irradiated by a dye laser tuned near the 460.73 nm ( 1 P 1 0 - 1 S 0 ) resonance transition. Collision-induced fluorescence at the resonance frequency and Rayleigh scattering at the laser frequency were studied as a function of detuning Delta over a range of about 30 nm (1500 cm -1 ). The Rayleigh component was found to vary as Delta -2 , as expected, whereas the collision-induced fluorescence was markedly asymmetric. This experiment constitutes a direct measurement of the redistribution function.

Journal of Physics B Atomic and Molecular Physics•Jun 21, 1976•39 citations

Collisional redistribution of light: Far-wing line shapes and polarizations for the Ba-(Ar,Xe) systems

W. J. Alford, N. Andersen, Keith R. Burnett +1 more

We have measured the far-wing collisional redistribution line shape, the redistributed fluorescence polarization, and the collisional alignment decay rates for barium perturbed by argon and xenon. The experiment was performed with a heated gas cell ($T\ensuremath{\sim}900$ K) with perturber-gas densities in the 1---30-Torr range and laser light detuned \ifmmode\pm\else\textpm\fi{} 3--- 1000 ${\mathrm{cm}}^{\ensuremath{-}1}$ from the 5535-\AA{} Ba I $6^{1}S\ensuremath{-}6^{1}P$ resonance line. Metal-vapor densities were determined by a Rayleigh scattering technique, which is outlined in detail. By correlating structure in the line shape with that of the polarization, we are able to make definitive statements about the interatomic potentials. The Ba data show strong similarities with previous experimental results for similar two-electron atoms, namely Ca, Sr, and Hg, and so our conclusions are of relevance to these systems as well.

Physical Review A•Nov 1, 1984•87 citations

Redistribution of radiation in the absence of collisions

Gabriel G. Lombardi, Daniel E. Kelleher, J. Cooper

Redistribution and depolarization of near-resonant radiation is studied for the He 2(1P)-3(1D) line (668 nm) and some data for H-alpha (656 nm) are also presented. A Nd:YAG pumped dye laser, with a bandwidth of 0.1/cm and a power density of 100 kW/sq cm, is used in the experiment. The transitions have lower levels with natural line widths that are large compared with their upper-level natural widths, and, under experimental conditions, their collisional widths are also small. The ratio of fluorescence to Rayleigh intensity is measured and the results indicate that while the Rayleigh emission has the same temporal development as the laser pulse (5 ns FWHM), the fluorescent intensity has a decay time determined by the radiative decay lifetime and by collisional quenching. The prediction that redistribution of radiation occurs in the absence of collisions for transitions having significant lower-level radiative widths is confirmed. Depolarization rates by collisions with helium are also inferred from the measurements.

The Astrophysical Journal•Jan 1, 1985•4 citations
The authors have studied collisional redistribution of near-resonance radiation in thallium vapour caused by collisions with argon buffer gas. Electronic Raman scattering and collision-induced fluorescence were spectrally resolved, both to the weakly populated metastable 6 2 P 3/2 level in thallium. Thus the problem with radiative trapping encountered in previous experiments is partially avoided. By measuring the total collision-induced fluorescence as a function of the incident laser frequency, the absolute collisional redistribution line shape is obtained.
We have observed collisional redistribution of laser light scattered by a three-level atom, thallium, in the presence of argon. The two observed spectral components correspond to Raman scattering and collision-induced fluorescence. We have seen the growth of both components from spontaneous to stimulated scattering as the laser intensity is increased. While the gain for the Raman component agrees with theory, the observed gain of the collision-induced fluorescence is over an order of magnitude lower than predicted.
This paper reports on our studies of near-resonant scattering of laser light in a collisional environment. A pulsed dye laser with a peak power of 55 MW/cm2{\mathrm{cm}}^{2}cm2 was tuned near the 460.73-nm resonance line of strontium and the side emission was observed from an oven containing both strontium vapor and argon buffer gas. The emission was composed of three spectral components: Rayleigh scattering at the frequency of the laser ${\ensuremath{\omega}}_{L}$, fluorescence at the resonance frequency ${\ensuremath{\omega}}_{0}$ of strontium, and a third component at $2{\ensuremath{\omega}}_{L}\ensuremath{-}{\ensuremath{\omega}}_{0}$. These three components have been studied as a function of the frequency and intensity of the laser and also as a function of the argon buffer gas pressure. While the Rayleigh emission was found to vary as ${\ensuremath{\Delta}}^{\ensuremath{-}2}$ ($\ensuremath{\Delta}={\ensuremath{\omega}}_{0}\ensuremath{-}{\ensuremath{\omega}}_{L}$), the fluorescence component, which was produced by Sr-Ar collisions, was found to be asymmetric with the sign of $\ensuremath{\Delta}$ as predicted by line-broadening theory. By measuring the ratio of the intensities of the fluorescence and Rayleigh components, we were able to measure directly the collisional redistribution function, important in the study of radiative transfer in stellar and planetary atmospheres. At high laser intensities all three components were found to saturate. The results were compared with the theoretical predictions of Mollow's steady-state theory. Theoretical fits for the high-intensity results were obtained when the collisional cross sections were taken to be considerably smaller than in our low-intensity measurements. We believe the discrepancy lies in the use of a steady-state theory for a transient experiment. Effects of radiative trapping and spatial averaging are also discussed.
By tuning a pulsed dye laser through the resonance line of calcium at 422.7 nm the authors have investigated the spectral redistribution of laser radiation by calcium vapour. Two main components were resolved in the side emission from an oven containing calcium vapour and argon buffer gas. These are produced by Rayleigh scattering and by collision-induced fluorescence. The intensity of the Rayleigh component was found to vary as Delta -2 where Delta = omega 21 - omega L is the laser detuning from resonance. In contrast the intensity of the collision-induced fluorescence showed a markedly asymmetric dependence on detuning. Detailed studies of the collision-induced fluorescence have enabled the complete line shape of the calcium resonance line perturbed by argon to be determined. The interpretation of this data in terms of a frequency-dependent collision rate, gamma E ( Delta ), is discussed. This paper also reports calculations of theoretical line profiles using the unified Franck-Condon theory and trial interatomic difference potentials. The comparison of the experimental and theoretical line profiles enables the range of validity of the unified Franck-Condon theory to be assessed and the form of the optimum Ca-Ar difference potential to be selected.
Strontium vapour was irradiated by a dye laser tuned near the 460.73 nm ( 1 P 1 0 - 1 S 0 ) resonance transition. Collision-induced fluorescence at the resonance frequency and Rayleigh scattering at the laser frequency were studied as a function of detuning Delta over a range of about 30 nm (1500 cm -1 ). The Rayleigh component was found to vary as Delta -2 , as expected, whereas the collision-induced fluorescence was markedly asymmetric. This experiment constitutes a direct measurement of the redistribution function.
We have measured the far-wing collisional redistribution line shape, the redistributed fluorescence polarization, and the collisional alignment decay rates for barium perturbed by argon and xenon. The experiment was performed with a heated gas cell ($T\ensuremath{\sim}900$ K) with perturber-gas densities in the 1---30-Torr range and laser light detuned \ifmmode\pm\else\textpm\fi{} 3--- 1000 ${\mathrm{cm}}^{\ensuremath{-}1}$ from the 5535-\AA{} Ba I $6^{1}S\ensuremath{-}6^{1}P$ resonance line. Metal-vapor densities were determined by a Rayleigh scattering technique, which is outlined in detail. By correlating structure in the line shape with that of the polarization, we are able to make definitive statements about the interatomic potentials. The Ba data show strong similarities with previous experimental results for similar two-electron atoms, namely Ca, Sr, and Hg, and so our conclusions are of relevance to these systems as well.
Redistribution and depolarization of near-resonant radiation is studied for the He 2(1P)-3(1D) line (668 nm) and some data for H-alpha (656 nm) are also presented. A Nd:YAG pumped dye laser, with a bandwidth of 0.1/cm and a power density of 100 kW/sq cm, is used in the experiment. The transitions have lower levels with natural line widths that are large compared with their upper-level natural widths, and, under experimental conditions, their collisional widths are also small. The ratio of fluorescence to Rayleigh intensity is measured and the results indicate that while the Rayleigh emission has the same temporal development as the laser pulse (5 ns FWHM), the fluorescent intensity has a decay time determined by the radiative decay lifetime and by collisional quenching. The prediction that redistribution of radiation occurs in the absence of collisions for transitions having significant lower-level radiative widths is confirmed. Depolarization rates by collisions with helium are also inferred from the measurements.