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

Soviet Journal of Quantum Electronics

Isotopically selective light-induced drift of atoms in a field of counterpropagating waves

A. G. Bakhtadze, V. M. Vetsko, Andrei N Starostin, T R Khukhunashvili

Published Oct 31, 1984• 0 citations
Publisher

Abstract

Results are presented of a theoretical analysis of isotopically selective excitation of atoms in a field of counterpropagating waves with incomplete compensation for Doppler broadening. A density matrix formalism based on a strong collision model in a homogeneous steady-state case is used to obtain expressions for the total excitation probabilities and for the drift velocities of the resonant and nonresonant isotopes. An essentially new possibility for obtaining an asymmetric distribution function as a result of the dynamic two-photon Stark effect is noted whereby a light-induced drift (LID) can also be observed at exact resonance. Simple analytic expressions are derived for many cases and these can be used to analyze the dependence of the excitation and the drift velocity on the main characteristics of the process. Numerical estimates are given of the atomic parameters of alkali metals. The advantages of using this method for isotope separation compared with one-photon LID are discussed.

DOI
10.1070/qe1984v014n10abeh006433

Related papers

Isotopically selective two-photon excitation of a three-level atom

A. G. Bakhtadze, V. M. Vetsko, Andrei N Starostin +1 more

A theoretical analysis is made of the process of isotopically selective excitation of atoms in the field of opposite waves when the compensation of the Doppler broadening is incomplete. The density matrix formalism for a homogeneous steady-state case is used to obtain expressions for the total probability of the excitation of resonating and nonresonating isotopes and for the selectivity of the process defined as the ratio of these probabilities. In some cases analytic expressions are obtained and these make it possible to determine the nature of the dependence of the total probability of the excitation and selectivity on the temperature of a vapor, buffer gas concentration, ratio of the Rabi transition frequencies, detuning from a resonance, and isotopic shifts. Numerical estimates are obtained of the atomic parameters for transitions in potassium and rubidium atoms. It is shown that the adopted method is more promising for the separation of the isotopes of alkali metals than is one-photon excitation.

Soviet Journal of Quantum Electronics•Oct 31, 1983•2 citations

Theory of high-field effects in light-induced drift

Faris Gel’mukhanov, Jos E. M. Haverkort, S. W. M. Borst +1 more

We address theoretically the effects of a large laser intensity on the phenomenon of light-induced drift. The velocity selectivity of the atom-field interaction decreases due to saturation broadening and this leads to a maximum of the drift velocity as a function of the laser intensity. Analytical expressions for the drift velocity are derived in the case of two-level atoms, assuming a strong collision model. Consequences of this high-field effect are discussed for various manifestations of light-induced drift such as propagation of a soliton in an infinitely long cell, described by the Burgers equation, and collisions of such solitons. The analogy with hydrodynamic shock waves, described by the same Burgers equation, is fruitfully explored. We also address high-field effects on the density distribution produced by light-induced drift in a finite cell. In all these manifestations of light-induced drift the cases of high field and low field show qualitatively different behaviors which are of a complementary nature.

Physical Review A•Jul 1, 1987•18 citations

Spectral anomalies of light-induced drift of rubidium and lithium under monochromatic excitation

Faris Gel’mukhanov, А. И. Пархоменко, Timofei Privalov +1 more

The anomalous light-induced drift (LID) of atoms caused by a velocity dependence of collision frequencies has been investigated in the frame of the theory without adjustable parameters. Our results open the possibility of experimental probing of models of interatomic potentials. The extension of the strong-collision model to the case of velocity-dependent collision rates, is the basis of our approach. The obtained model describes the anomalous LID both in the case of arbitrary mass ratio of absorbing- and buffer-gas particles and in the case of arbitrary ratio of the homogeneous and Doppler widths. In particular, we applied our model to describe the anomalous LID in alkali - noble-gas mixtures (Rb - Kr and Li - Ne systems). Qualitatively another anomaly of the LID velocity was also found in the low-pressure region. As pointed out, the optical pumping effect and the hyperfine structure of the ground electronic state, but not the velocity dependence of the collision rates, are the sources of this new anomaly.

Journal of Physics B Atomic Molecular and Optical Physics•Apr 14, 1997•14 citations

Light-induced drift with low-power spectrally shaped lasers: efficient isotope separation and high drift velocities

E. R. Eliel, Alan D. Streater, J. P. Woerdman

The use of paraffin-coated cells has led to a breakthrough in the experimental study of light-induced drift (LID) of alkalis in noble gases. In recent experiments isotope separation of the two naturally occurring Rb isotopes through the LID effect has been achieved (enrichment of the rare isotope up to 95%), 1,2 and direct measurements of the drift velocity of Na in noble gases as a function of various experimental parameters have been made.3 In these experiments a single single-mode dye laser, tuned within the Doppler profile of the resonance line, was used to excite a specific velocity group of atoms (isotope selective in the case of Rb). Optical pumping between the ground-state hyperfine levels F = I+½ and F=I−½ plays a dominant (limiting) role in determining the magnitude of the LID effects by strongly depleting the resonantly excited hyperfine substate (of a specific isotope).

Conference on Lasers and Electro-Optics•Apr 25, 1988•0 citations

Numerical study of light-induced drift of Na in noble gases

Jos E. M. Haverkort, H. G. C. Werij, J. P. Woerdman

We present a model for light-induced drift (LID) in the Na--noble-gas system which should enable direct comparison with experiment. In contrast to previous theories of LID based on a two-level description of the optical absorbers and on a simplified collision treatment, the present model is based on a realistic description of laser-driven Na atoms immersed in a buffer gas. Starting from the generalized Bloch equations, we introduce a rate-equation model for the velocity distributions in the four important Na levels. The velocity-changing and fine-structure-changing collisions are described using composite Keilson-Storer collision kernels in which all adjustable parameters have been eliminated by using available literature data. We apply the model in numerical calculations of LID as a function of all experimentally accessible parameters. It is found that the ground-state hyperfine splitting can have large effects on LID, whereas the excited-state fine-structure splitting has not. The paper establishes criteria for optimum LID effects; when using a single-frequency laser the maximum attainable drift velocity is predicted to be 13.8 m/s. Using a proper set of boundary conditions, we find a pressure dependence of LID qualitatively different from the predictions based on previous work. Finally, the influence of the collision model is investigated. We find that LID is independent of the shape of the collision kernel, indicating that a strong-collision model is always valid.

Physical Review A•Oct 1, 1988•25 citations

Detuning from intermediate resonance dependence of the atomic three-step pulse photo-ionization selectivity in powerful laser fields

Sergey V. Fomichev

The selectivity of three-step pulse photo-ionization of atoms versus the detuning delta of exciting radiation frequencies from intermediate resonance is investigated in powerful laser fields where the power broadening of the resonant transitions is at least of the order of isotope shifts. The Doppler broadening of the resonant transitions is taken into account and it is assumed that the sum frequency of both exciting laser radiations is tuned to the line centre of the two-photon transition of a selected isotope. It is shown that in this situation the photo-ionization selectivity increases so greatly with the absolute detuning mod delta mod that even in such strong fields the process of photo-ionization can be highly selective. The optimization of selective photo-ionization of atoms is discussed in connection with the decrease in the selective isotope yield with increase of the absolute detuning mod delta mod . Analytical consideration of selective three-step pulse photo-ionization in powerful laser fields, based on the density matrix formalism, is presented together with the results of numerical simulation of the 40 Ca- 48 Ca laser isotope separation process as an example.

Journal of Physics D Applied Physics•Mar 14, 1993•2 citations
Results are presented of a theoretical analysis of isotopically selective excitation of atoms in a field of counterpropagating waves with incomplete compensation for Doppler broadening. A density matrix formalism based on a strong collision model in a homogeneous steady-state case is used to obtain expressions for the total excitation probabilities and for the drift velocities of the resonant and nonresonant isotopes. An essentially new possibility for obtaining an asymmetric distribution function as a result of the dynamic two-photon Stark effect is noted whereby a light-induced drift (LID) can also be observed at exact resonance. Simple analytic expressions are derived for many cases and these can be used to analyze the dependence of the excitation and the drift velocity on the main characteristics of the process. Numerical estimates are given of the atomic parameters of alkali metals. The advantages of using this method for isotope separation compared with one-photon LID are discussed.
A theoretical analysis is made of the process of isotopically selective excitation of atoms in the field of opposite waves when the compensation of the Doppler broadening is incomplete. The density matrix formalism for a homogeneous steady-state case is used to obtain expressions for the total probability of the excitation of resonating and nonresonating isotopes and for the selectivity of the process defined as the ratio of these probabilities. In some cases analytic expressions are obtained and these make it possible to determine the nature of the dependence of the total probability of the excitation and selectivity on the temperature of a vapor, buffer gas concentration, ratio of the Rabi transition frequencies, detuning from a resonance, and isotopic shifts. Numerical estimates are obtained of the atomic parameters for transitions in potassium and rubidium atoms. It is shown that the adopted method is more promising for the separation of the isotopes of alkali metals than is one-photon excitation.
We address theoretically the effects of a large laser intensity on the phenomenon of light-induced drift. The velocity selectivity of the atom-field interaction decreases due to saturation broadening and this leads to a maximum of the drift velocity as a function of the laser intensity. Analytical expressions for the drift velocity are derived in the case of two-level atoms, assuming a strong collision model. Consequences of this high-field effect are discussed for various manifestations of light-induced drift such as propagation of a soliton in an infinitely long cell, described by the Burgers equation, and collisions of such solitons. The analogy with hydrodynamic shock waves, described by the same Burgers equation, is fruitfully explored. We also address high-field effects on the density distribution produced by light-induced drift in a finite cell. In all these manifestations of light-induced drift the cases of high field and low field show qualitatively different behaviors which are of a complementary nature.
The anomalous light-induced drift (LID) of atoms caused by a velocity dependence of collision frequencies has been investigated in the frame of the theory without adjustable parameters. Our results open the possibility of experimental probing of models of interatomic potentials. The extension of the strong-collision model to the case of velocity-dependent collision rates, is the basis of our approach. The obtained model describes the anomalous LID both in the case of arbitrary mass ratio of absorbing- and buffer-gas particles and in the case of arbitrary ratio of the homogeneous and Doppler widths. In particular, we applied our model to describe the anomalous LID in alkali - noble-gas mixtures (Rb - Kr and Li - Ne systems). Qualitatively another anomaly of the LID velocity was also found in the low-pressure region. As pointed out, the optical pumping effect and the hyperfine structure of the ground electronic state, but not the velocity dependence of the collision rates, are the sources of this new anomaly.
The use of paraffin-coated cells has led to a breakthrough in the experimental study of light-induced drift (LID) of alkalis in noble gases. In recent experiments isotope separation of the two naturally occurring Rb isotopes through the LID effect has been achieved (enrichment of the rare isotope up to 95%), 1,2 and direct measurements of the drift velocity of Na in noble gases as a function of various experimental parameters have been made.3 In these experiments a single single-mode dye laser, tuned within the Doppler profile of the resonance line, was used to excite a specific velocity group of atoms (isotope selective in the case of Rb). Optical pumping between the ground-state hyperfine levels F = I+½ and F=I−½ plays a dominant (limiting) role in determining the magnitude of the LID effects by strongly depleting the resonantly excited hyperfine substate (of a specific isotope).
We present a model for light-induced drift (LID) in the Na--noble-gas system which should enable direct comparison with experiment. In contrast to previous theories of LID based on a two-level description of the optical absorbers and on a simplified collision treatment, the present model is based on a realistic description of laser-driven Na atoms immersed in a buffer gas. Starting from the generalized Bloch equations, we introduce a rate-equation model for the velocity distributions in the four important Na levels. The velocity-changing and fine-structure-changing collisions are described using composite Keilson-Storer collision kernels in which all adjustable parameters have been eliminated by using available literature data. We apply the model in numerical calculations of LID as a function of all experimentally accessible parameters. It is found that the ground-state hyperfine splitting can have large effects on LID, whereas the excited-state fine-structure splitting has not. The paper establishes criteria for optimum LID effects; when using a single-frequency laser the maximum attainable drift velocity is predicted to be 13.8 m/s. Using a proper set of boundary conditions, we find a pressure dependence of LID qualitatively different from the predictions based on previous work. Finally, the influence of the collision model is investigated. We find that LID is independent of the shape of the collision kernel, indicating that a strong-collision model is always valid.
The selectivity of three-step pulse photo-ionization of atoms versus the detuning delta of exciting radiation frequencies from intermediate resonance is investigated in powerful laser fields where the power broadening of the resonant transitions is at least of the order of isotope shifts. The Doppler broadening of the resonant transitions is taken into account and it is assumed that the sum frequency of both exciting laser radiations is tuned to the line centre of the two-photon transition of a selected isotope. It is shown that in this situation the photo-ionization selectivity increases so greatly with the absolute detuning mod delta mod that even in such strong fields the process of photo-ionization can be highly selective. The optimization of selective photo-ionization of atoms is discussed in connection with the decrease in the selective isotope yield with increase of the absolute detuning mod delta mod . Analytical consideration of selective three-step pulse photo-ionization in powerful laser fields, based on the density matrix formalism, is presented together with the results of numerical simulation of the 40 Ca- 48 Ca laser isotope separation process as an example.