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 de physique

Velocity selective optical pumping

C.G. Aminoff, M. Pinard

Published Jan 1, 1982• 42 citations
Publisher

Abstract

We consider optical pumping with a quasi monochromatic tunable light beam, in the low intensity limit where a rate equation regime is obtained The velocity selective optical pumping (V.S.O.P.) introduces a correlation between atomic velocity and internal variables in the ground (or metastable) state. The aim of this article is to evaluate these atomic observables (orientation, alignment, population) as a function of velocity, using a phenomenological description of the relaxation effect of collisions. The V.S.O.P. line shapes, obtained by scanning the pumping beam frequency and using a counterpropagating detection beam with the same frequency, are given in various circumstances. The combination of V.S.O.P. with modulated pumping, magnetic resonance, and level crossing methods is considered; the corresponding line shapes can provide useful information on the relaxation characteristics, such as collision rates and kernels.

DOI
10.1051/jphys:01982004302026300

Related papers

Velocity-selective optical pumping and collision effects

C.G. Aminoff

Optical pumping performed with a quasi monochromatic laser beam in an atomic gas introduces a redistribution of Zeeman populations selectively in a single velocity class. In the limit of low pumping intensity the rate theory is valid for a description of velocity-selective optical pumping (V.S.O.P.). Well-defined atomic observables (population, orientation, alignment) and their velocity-correlated collisional relaxation can be studied. Also, a modified scheme for the detection of second order effects of optical pumping allows one to observe light shift induced signals. In particular, V.S.O.P. and its combination with modulated pumping, magnetic depolarization (level crossing), and magnetic resonance techniques provide information about the atomic collision characteristics such as collision rates and kernels for velocity-changing collisions.

Annales de Physique•Jan 1, 1985•2 citations

Velocity-selective optical pumping and Doppler-free spectroscopy

M. Pinard, C.G. Aminoff, Franck Laloë

We describe a spectroscopic method combining saturated absorption and Zeeman optical pumping. A weak expanded monochromatic laser beam creates a velocity-correlated orientation in an atomic level without optical saturation. A polarization-modulated counterpropagating detection beam provides signals related to simple atomic observables. Combination with magnetic resonance techniques is described. We have applied this method to metastable states of Ne, with nuclear or electronic orientation. Effects of velocity-changing, depolarization (Kastler- or Dehmelt-type pumping) or metastability exchange collisions are discussed.

Physical Review A•Jun 1, 1979•78 citations

Collision effects in velocity-selective optical pumping of sodium

C.G. Aminoff, Juha Javanainen, M. Kaivola

We report on a quantitative experimental investigation of velocity-changing collisions by means of velocity-selective optical pumping (VSOP). We have calculated the VSOP line shape for an atom with hyperfine structure with the use of two phenomenological kernels for the collision effects: the Keilson-Storer kernel, and a two-term kernel consisting of a broad Keilson-Storer part and a narrower Gaussian component. Corrections were included to account for the finite absorption in the sample and the backward reflection of the pumping beam. The experiments were carried out in sodium vapor with neon as the perturber gas. The ${D}_{1}$ line of sodium was used for optical pumping, and the orientation of the ground state was detected. Free parameters of the theory were determined by fitting the predicted line shapes to experimental curves. The Keilson-Storer kernel proved unsatisfactory, but the two-term kernel reproduced well the observed line shapes over the entire collision profiles in the neon pressure range 0-57 mtorr. In an independent experiment using rapidly modulated VSOP we also measured directly the cross section of velocity-changing collisions: $\ensuremath{\sigma}=(1.13\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}$ ${\mathrm{cm}}^{2}$. The large weight obtained for the narrow Gaussian from the fits, as well as the collision cross section which is three times as large as the cross section deduced from tabulated gas kinetic radii, may indicate the presence of collisions with relatively small velocity changes in addition to hard-sphere encounters.

Physical Review A•Aug 1, 1983•36 citations

Optogalvanic detection of optical pumping

Lucile Julien, M. Pinard

Reports the optogalvanic detection of observables induced by optical pumping in metastable states of neon. As with optical methods signals are obtained which are related to electronic and nuclear orientation or alignment. Many optical pumping experiments may thus be performed using optogalvanic techniques, including the Hanle effect and 'velocity selective optical pumping' described. Different mechanisms are discussed from which optogalvanic signals related to non-scalar observables may originate. Profiles obtained from frequency sweeps of two polarisation-modulated counterpropagating pump beams indicate the dominant mechanism is a second-order pumping effect which induces a modulated depletion of the metastable state. No effect has been observed arising from a variation of the Penning collision cross section when the two metastable colliding atoms are oriented. The analogy between signals produced by optogalvanic and optical methods are pointed out.

Journal of Physics B Atomic and Molecular Physics•Sep 4, 1982•17 citations

Distortion of on-resonance two-photon spectroscopic line shapes caused by velocity-selective optical pumping

John E. Bjorkholm, P. F. Liao, Alexander J. Wokaun

We have observed that spectral lines obtained in sodium vapor can be strongly distroted when using two-photon spectroscopy with a resonant intermediate state. In some cases, the spectral lines appear to be split into two components. We demonstrate that these effects are due to velocity-selective optical pumping of the atomic ground state; the line shapes reflect the velocity distribution of atoms in the excited intermediate state. We have analyzed the effects using the time-dependent solutions of the rate equations which describe the time evolution of optical pumping for the various atomic velocity groups, and we obtain good agreement with experiment. Optical-pumping problems are often analyzed with the use of steady-state rate equations which incorporate phenomenological relaxation; such approaches are not capable of describing our observations. Velocity-changing collisions are shown to suppress the effects and they explain why these effects were not previously observed; the previous experiments were carried out with slight amounts of a buffer gas in the vapor cell. The effects reported here must be accounted for when carrying out laser-induced line-narrowing experiments in atoms or molecules that can be optically pumped; they can also be used as a new and more sensitive probe of optical pumping in vapors.

Physical Review A•Nov 1, 1982•32 citations

On the Sub-Doppler Spectroscopy of Optically Excited Atoms in a Thin Gas Cell

А. Ч. Измайлов

This work continues a theoretical investigation of the capabilities of the well-known method based on using a monochromatic probe light beam in combination with optical pumping of atoms (molecules) of a rarefied-gas medium by a broadband radiation in a thin cell the diameter of which is much larger than its internal thickness. In contrast to calculations carried out in the previous publications on this method of spectroscopy, here, we consider the case of arbitrary values of pump intensity and thickness of a cylindrical gas cell. Thus, all the possible mechanisms and specificities of velocity selection of atoms in optically excited levels caused by transit-time relaxation of such atoms in gas cells of this kind are analyzed. Within the framework of this approach, sub-Doppler absorption resonances of the probe light beam corresponding to quantum transitions from the upper level excited by optical pumping are investigated. The obtained results can be used in high-resolution spectroscopy of atoms (molecules), as well as for laser-frequency stabilization to established narrow spectral resonances.

Optics and Spectroscopy•Jun 1, 2018•1 citation
We consider optical pumping with a quasi monochromatic tunable light beam, in the low intensity limit where a rate equation regime is obtained The velocity selective optical pumping (V.S.O.P.) introduces a correlation between atomic velocity and internal variables in the ground (or metastable) state. The aim of this article is to evaluate these atomic observables (orientation, alignment, population) as a function of velocity, using a phenomenological description of the relaxation effect of collisions. The V.S.O.P. line shapes, obtained by scanning the pumping beam frequency and using a counterpropagating detection beam with the same frequency, are given in various circumstances. The combination of V.S.O.P. with modulated pumping, magnetic resonance, and level crossing methods is considered; the corresponding line shapes can provide useful information on the relaxation characteristics, such as collision rates and kernels.
Optical pumping performed with a quasi monochromatic laser beam in an atomic gas introduces a redistribution of Zeeman populations selectively in a single velocity class. In the limit of low pumping intensity the rate theory is valid for a description of velocity-selective optical pumping (V.S.O.P.). Well-defined atomic observables (population, orientation, alignment) and their velocity-correlated collisional relaxation can be studied. Also, a modified scheme for the detection of second order effects of optical pumping allows one to observe light shift induced signals. In particular, V.S.O.P. and its combination with modulated pumping, magnetic depolarization (level crossing), and magnetic resonance techniques provide information about the atomic collision characteristics such as collision rates and kernels for velocity-changing collisions.
We describe a spectroscopic method combining saturated absorption and Zeeman optical pumping. A weak expanded monochromatic laser beam creates a velocity-correlated orientation in an atomic level without optical saturation. A polarization-modulated counterpropagating detection beam provides signals related to simple atomic observables. Combination with magnetic resonance techniques is described. We have applied this method to metastable states of Ne, with nuclear or electronic orientation. Effects of velocity-changing, depolarization (Kastler- or Dehmelt-type pumping) or metastability exchange collisions are discussed.
We report on a quantitative experimental investigation of velocity-changing collisions by means of velocity-selective optical pumping (VSOP). We have calculated the VSOP line shape for an atom with hyperfine structure with the use of two phenomenological kernels for the collision effects: the Keilson-Storer kernel, and a two-term kernel consisting of a broad Keilson-Storer part and a narrower Gaussian component. Corrections were included to account for the finite absorption in the sample and the backward reflection of the pumping beam. The experiments were carried out in sodium vapor with neon as the perturber gas. The D1{D}_{1}D1​ line of sodium was used for optical pumping, and the orientation of the ground state was detected. Free parameters of the theory were determined by fitting the predicted line shapes to experimental curves. The Keilson-Storer kernel proved unsatisfactory, but the two-term kernel reproduced well the observed line shapes over the entire collision profiles in the neon pressure range 0-57 mtorr. In an independent experiment using rapidly modulated VSOP we also measured directly the cross section of velocity-changing collisions: $\ensuremath{\sigma}=(1.13\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}$ cm2{\mathrm{cm}}^{2}cm2. The large weight obtained for the narrow Gaussian from the fits, as well as the collision cross section which is three times as large as the cross section deduced from tabulated gas kinetic radii, may indicate the presence of collisions with relatively small velocity changes in addition to hard-sphere encounters.
Reports the optogalvanic detection of observables induced by optical pumping in metastable states of neon. As with optical methods signals are obtained which are related to electronic and nuclear orientation or alignment. Many optical pumping experiments may thus be performed using optogalvanic techniques, including the Hanle effect and 'velocity selective optical pumping' described. Different mechanisms are discussed from which optogalvanic signals related to non-scalar observables may originate. Profiles obtained from frequency sweeps of two polarisation-modulated counterpropagating pump beams indicate the dominant mechanism is a second-order pumping effect which induces a modulated depletion of the metastable state. No effect has been observed arising from a variation of the Penning collision cross section when the two metastable colliding atoms are oriented. The analogy between signals produced by optogalvanic and optical methods are pointed out.
We have observed that spectral lines obtained in sodium vapor can be strongly distroted when using two-photon spectroscopy with a resonant intermediate state. In some cases, the spectral lines appear to be split into two components. We demonstrate that these effects are due to velocity-selective optical pumping of the atomic ground state; the line shapes reflect the velocity distribution of atoms in the excited intermediate state. We have analyzed the effects using the time-dependent solutions of the rate equations which describe the time evolution of optical pumping for the various atomic velocity groups, and we obtain good agreement with experiment. Optical-pumping problems are often analyzed with the use of steady-state rate equations which incorporate phenomenological relaxation; such approaches are not capable of describing our observations. Velocity-changing collisions are shown to suppress the effects and they explain why these effects were not previously observed; the previous experiments were carried out with slight amounts of a buffer gas in the vapor cell. The effects reported here must be accounted for when carrying out laser-induced line-narrowing experiments in atoms or molecules that can be optically pumped; they can also be used as a new and more sensitive probe of optical pumping in vapors.
This work continues a theoretical investigation of the capabilities of the well-known method based on using a monochromatic probe light beam in combination with optical pumping of atoms (molecules) of a rarefied-gas medium by a broadband radiation in a thin cell the diameter of which is much larger than its internal thickness. In contrast to calculations carried out in the previous publications on this method of spectroscopy, here, we consider the case of arbitrary values of pump intensity and thickness of a cylindrical gas cell. Thus, all the possible mechanisms and specificities of velocity selection of atoms in optically excited levels caused by transit-time relaxation of such atoms in gas cells of this kind are analyzed. Within the framework of this approach, sub-Doppler absorption resonances of the probe light beam corresponding to quantum transitions from the upper level excited by optical pumping are investigated. The obtained results can be used in high-resolution spectroscopy of atoms (molecules), as well as for laser-frequency stabilization to established narrow spectral resonances.