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 Molecular and Optical Physics

A LICET process involving metastable singlet helium

Ricardo Joseph Simeoni, G. Peach, Ian B. Whittingham

Published Feb 28, 1997• 2 citations
Publisher

Abstract

The laser-induced collisional energy transfer (LICET) profile has been calculated for the process based upon a fully quantum treatment of the interactions and the use of model adiabatic molecular potentials. The weak-field LICET profile obtained is very broad, strongly shifted from zero laser detuning and does not display the characteristic antistatic and quasistatic wing shapes. The profile is very sensitive to the nature of the molecular potentials at interatomic separations of less than .

DOI
10.1088/0953-4075/30/4/024

Related papers

Theoretical study of a LICET-like process in singlet helium systems

Ricardo Joseph Simeoni, G. Peach, Ian B. Whittingham

A fully quantum treatment of the laser induced collisional energy transfer (LICET) processes, , where n = 3,4, is presented, which allows for non-adiabatic mixing between molecular states during the collision. LICET profiles have been calculated for both Lennard-Jones 12 - 6 and model adiabatic molecular potentials. The weak field LICET profiles obtained differ from those of conventional mixed metal vapour systems in that they are very broad, significantly shifted from zero detuning and exhibit novel complex resonant structure in the quasistatic wing. The profiles are very sensitive to the nature of the molecular potential at internuclear separations of less than and consequently differ greatly for the two sets of potentials used.

Journal of Physics B Atomic Molecular and Optical Physics•Nov 28, 1996•3 citations

Calculations on laser-induced collisional energy transfer

S. Geltman

We examine theoretically the behavior of cross sections for laser-induced collisional energy transfer (LICET) over a wide range of detunings and laser intensities for the two-atom pairs Li-Sr and Eu-Sr which have been previously studied experimentally. These two cases are complementary in that the laser and collisional interactions enter in opposite orders, and their level structures are such as to give weak-field line shapes of opposite asymmetry and intensity shift. A three-state model is used and the Bambini-Berman formula for the weak-field quasistatic wing is verified. At high intensities the peak cross section is found to go through a maximum and the LICET profile is found to become symmetric about a shifted center with notable departures from a uniform falloff in the far quasistatic wing, apparently arising from radiative collisional interference effects.

Physical Review A•Apr 1, 1992•21 citations

Quasistatic wing behavior of collisional-radiative line profiles

Arturo Bambini, P. R. Berman

It is shown that the conventional two-state theory of laser-induced collisional energy transfer (LICET) cannot be expected to provide an adequate description of the quasistatic wing behavior observed in a number of high-resolution LICET experiments. The theory breaks down whenever the detuning parameter \ensuremath{\Delta} of the LICET reaction is comparable to some frequency mismatch \ensuremath{\delta}\ensuremath{\omega} between either the initial or final state and a (virtual) intermediate state in the reaction. A simple extension of the conventional two-state theory is presented which leads to good agreement with experiment. For a van der Waals collisional interaction, the quasistatic wing is shown to fall off as \ensuremath{\Vert}\ensuremath{\Delta}${\ensuremath{\Vert}}^{\mathrm{\ensuremath{-}}1/2}$(\ensuremath{\delta}\ensuremath{\omega}+\ensuremath{\Vert}\ensuremath{\Delta}\ensuremath{\Vert}${)}^{\mathrm{\ensuremath{-}}3/2}$ instead of \ensuremath{\Vert}\ensuremath{\Delta}${\ensuremath{\Vert}}^{\mathrm{\ensuremath{-}}1/2}$ predicted by the two-state theory.

Physical Review A•May 1, 1987•38 citations

Analysis of the far-wing behavior in the spectrum of the light-induced collisional-energy-transfer process

A. Agresti, P. R. Berman, Arturo Bambini +1 more

The behavior of the quasistatic wing of the light-induced collisional-energy-transfer (LICET) line shape is analyzed. The reaction can be written as ${A}^{\mathrm{*}}$+B+\ensuremath{\Elzxh}\ensuremath{\Omega}\ensuremath{\rightarrow}A+${B}^{\mathrm{*}\mathrm{*}}$. The two-level model is found to be inadequate to describe the falloff of the spectral line shape in the quasistatic wing. The three-level model, on the other hand, leads to the prediction of a cross section that depends on the detuning in various ways, according to the strength of the collisional coupling and the influence of the van der Waals shifts on the levels under consideration. Good agreement with existing experimental results is found. To check the approximations made in the derivation of these results, numerical evaluation of the transition probability has been performed for several cases. A Monte Carlo simulation of the full LICET spectrum is also presented.

Physical Review A•Sep 1, 1988•36 citations

Theory of strong-field light-induced collisional energy transfer in Eu and Sr

Arturo Bambini, S. Geltman

The theory of light-induced collisional energy transfer (LICET) in the Eu-Sr system is extended to include all the degenerate M states that occur in the separated-atom basis states. Previous treatments were restricted to only the M=0 substates. Numerical solutions are obtained for the resulting nine-state dynamic coupled system to determine transitions probabilities on a given straight-line path. Intense laser fields of linear and circular polarization are treated. It is found that the full M-state treatment results in dependences on the trajectory orientation angles which are much more complex than in the M=0 treatment. The exact and quasisymmetries involving these orientation angles are described in simple group-theoretic terms. The resulting spectral line shapes (LICET transition cross sections as a function of laser detuning) are seen to have structures that are understood in terms of the coupling matrix elements, as well as appreciable Stark shifts. These shifts, which appear to be an essential outcome of the theory, are not yet seen in measurements of the LICET line shape.

Physical Review A•Dec 1, 1994•14 citations

Calculation of laser induced collisional energy transfer in the Sr-Ca system

Lu Zhen

Based on the four-state model of laser-induced collisional energy transfer,the cross section of the collisional energy transfer in the Sr-Ca system is obtained.Various factors,including field intensity,relative speed,and temperature,which influence the collisional cross section,are discussed for illustrating the features of the Sr-Ca laser-induced collisional energy transfer(LICET) process.The calculated results show that the LICET spectral profiles obviously become narrower when the laser field intensity increases.The collision cross section rises with laser intensity and tends to saturate.In the vicinity of the spectral profile center,the cross section at fixed laser detuning becomes smaller as the relative speed and system temperature increase.The results indicate that the intermediate states strongly affect the spectral profile of LICET.

Science in China. Series G, Physics, mechanics & astronomy/Science in China. Series G, Physics, Mechanics & Astronomy•Jan 1, 2011•0 citations
The laser-induced collisional energy transfer (LICET) profile has been calculated for the process based upon a fully quantum treatment of the interactions and the use of model adiabatic molecular potentials. The weak-field LICET profile obtained is very broad, strongly shifted from zero laser detuning and does not display the characteristic antistatic and quasistatic wing shapes. The profile is very sensitive to the nature of the molecular potentials at interatomic separations of less than .
A fully quantum treatment of the laser induced collisional energy transfer (LICET) processes, , where n = 3,4, is presented, which allows for non-adiabatic mixing between molecular states during the collision. LICET profiles have been calculated for both Lennard-Jones 12 - 6 and model adiabatic molecular potentials. The weak field LICET profiles obtained differ from those of conventional mixed metal vapour systems in that they are very broad, significantly shifted from zero detuning and exhibit novel complex resonant structure in the quasistatic wing. The profiles are very sensitive to the nature of the molecular potential at internuclear separations of less than and consequently differ greatly for the two sets of potentials used.
We examine theoretically the behavior of cross sections for laser-induced collisional energy transfer (LICET) over a wide range of detunings and laser intensities for the two-atom pairs Li-Sr and Eu-Sr which have been previously studied experimentally. These two cases are complementary in that the laser and collisional interactions enter in opposite orders, and their level structures are such as to give weak-field line shapes of opposite asymmetry and intensity shift. A three-state model is used and the Bambini-Berman formula for the weak-field quasistatic wing is verified. At high intensities the peak cross section is found to go through a maximum and the LICET profile is found to become symmetric about a shifted center with notable departures from a uniform falloff in the far quasistatic wing, apparently arising from radiative collisional interference effects.
It is shown that the conventional two-state theory of laser-induced collisional energy transfer (LICET) cannot be expected to provide an adequate description of the quasistatic wing behavior observed in a number of high-resolution LICET experiments. The theory breaks down whenever the detuning parameter \ensuremath{\Delta} of the LICET reaction is comparable to some frequency mismatch \ensuremath{\delta}\ensuremath{\omega} between either the initial or final state and a (virtual) intermediate state in the reaction. A simple extension of the conventional two-state theory is presented which leads to good agreement with experiment. For a van der Waals collisional interaction, the quasistatic wing is shown to fall off as \ensuremath{\Vert}\ensuremath{\Delta}${\ensuremath{\Vert}}^{\mathrm{\ensuremath{-}}1/2}$(\ensuremath{\delta}\ensuremath{\omega}+\ensuremath{\Vert}\ensuremath{\Delta}\ensuremath{\Vert}${)}^{\mathrm{\ensuremath{-}}3/2}$ instead of \ensuremath{\Vert}\ensuremath{\Delta}${\ensuremath{\Vert}}^{\mathrm{\ensuremath{-}}1/2}$ predicted by the two-state theory.
The behavior of the quasistatic wing of the light-induced collisional-energy-transfer (LICET) line shape is analyzed. The reaction can be written as A∗{A}^{\mathrm{*}}A∗+B+\ensuremath{\Elzxh}\ensuremath{\Omega}\ensuremath{\rightarrow}A+B∗∗{B}^{\mathrm{*}\mathrm{*}}B∗∗. The two-level model is found to be inadequate to describe the falloff of the spectral line shape in the quasistatic wing. The three-level model, on the other hand, leads to the prediction of a cross section that depends on the detuning in various ways, according to the strength of the collisional coupling and the influence of the van der Waals shifts on the levels under consideration. Good agreement with existing experimental results is found. To check the approximations made in the derivation of these results, numerical evaluation of the transition probability has been performed for several cases. A Monte Carlo simulation of the full LICET spectrum is also presented.
The theory of light-induced collisional energy transfer (LICET) in the Eu-Sr system is extended to include all the degenerate M states that occur in the separated-atom basis states. Previous treatments were restricted to only the M=0 substates. Numerical solutions are obtained for the resulting nine-state dynamic coupled system to determine transitions probabilities on a given straight-line path. Intense laser fields of linear and circular polarization are treated. It is found that the full M-state treatment results in dependences on the trajectory orientation angles which are much more complex than in the M=0 treatment. The exact and quasisymmetries involving these orientation angles are described in simple group-theoretic terms. The resulting spectral line shapes (LICET transition cross sections as a function of laser detuning) are seen to have structures that are understood in terms of the coupling matrix elements, as well as appreciable Stark shifts. These shifts, which appear to be an essential outcome of the theory, are not yet seen in measurements of the LICET line shape.
Based on the four-state model of laser-induced collisional energy transfer,the cross section of the collisional energy transfer in the Sr-Ca system is obtained.Various factors,including field intensity,relative speed,and temperature,which influence the collisional cross section,are discussed for illustrating the features of the Sr-Ca laser-induced collisional energy transfer(LICET) process.The calculated results show that the LICET spectral profiles obviously become narrower when the laser field intensity increases.The collision cross section rises with laser intensity and tends to saturate.In the vicinity of the spectral profile center,the cross section at fixed laser detuning becomes smaller as the relative speed and system temperature increase.The results indicate that the intermediate states strongly affect the spectral profile of LICET.