Theory of collision effects on atomic and molecular line shapes

Berman, P. R.

doi:10.1007/bf00883644

Cited by 90 publications

(13 citation statements)

References 58 publications

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“…The coherences between the states experience a dephasing, which makes them relax to zero rapidly. This feature is of special importance in laser spectroscopy, where the external light sources couple to the induced dipoles; for a discussion see Berman [8,9]. The same holds true in quantum chemistry, where collisionally induced reactions go through a set of adiabatically defined reaction surfaces coupled by nonadiabatic perturbations; see the text [10]for a detailed discussion.…”

Section: Introductionmentioning

confidence: 88%

Semiclassical expansion for systems with internal degrees of freedom

Stenholm

1993

Phys. Rev. A

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In this paper, we consider a system with both translational degrees of freedom and a structure of discrete internal states. Applying a multiple-time-scale approach we can separate the dynamical processes describing internal quantum transitions between the states and semiclassical propagation in phase space. The freedom provided by the multiple-time-scale method seems to o8'er the possibility of carrying out such a separation without internal contradictions. The case with no internal states is extracted and compared with other semiclassical results in the literature; it is found that our approach can be related to these, but it is not identical with any previously reported results. When a unique particle trajectory can be defined, the procedure is shown to lead to the customary classical-path approximation often employed in scattering theory and quantum optics. This approach is generalized into a self-consistent method, but it is not expected to be applicable in the coherence-destroying case with widely separated trajectories for the internal states. The validity of the approach and its limitations are discussed.

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Section: Introductionmentioning

confidence: 88%

Semiclassical expansion for systems with internal degrees of freedom

Stenholm

1993

Phys. Rev. A

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“…The formula (58) is obtained from the calculated "non-resonant" coefficient A + 2 (see expression (43)) giving the order of the second harmonic (frequency 2ω) of the population grating which is Rabi pump /ω ∼ 10 −6 (for the conditions in [1]) in comparison with the zero harmonic perturbation described by the coefficient (57) (resulting from the expression (40)). The corresponding "anti-resonance" term in (37) or (38) yields the appearance of the population grating such as in (55). The same is expected for the third harmonic in the polarization lattice: taking into account the found coefficient C − 3 (expression (44)) we obtain the non-resonant polarization lattice with the order of the ratio between the field Rabi frequency (∼ 10 9 Hz for pump) and the field frequency (Rabi pump /ω) that is of the order 10 −6 (for the visible region) in comparison with the first harmonic perturbation (with the frequency ω) described by the coefficient C − 1 (see expression (41)).…”

Section: The Region N ∈ (10 3 ∞)mentioning

confidence: 99%

“…A review of the relatively early developments in the theory of the effects of binary collisions on the spectral profiles is presented in [37] with respect to the simplified master equations for one-particle density matrix elements including some phenomenological items taking into account atomic transitions at the short-range collisions.…”

Section: Introduction and Motivationsmentioning

confidence: 99%

Kinetics and Optical Properties of the Strongly Driven Gas Medium of Interacting Atoms

Sizhuk

Hemmer

2012

J Stat Phys

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This paper investigates stimulated emission and absorption near resonance for a driven system of interacting two-level atoms. Microscopic kinetic equations for the density matrix elements of N -atom states including atomic motion are built, taking into account atom-field and atom-atom interactions. Analytical solutions are given for the resulting macroscopic equations in different limits, for a system composed of a strong coherent "pump" field and a weak counter-propagating "probe" field. It was shown that the existence of a dipole-dipole (long-range) interaction between atoms separated by distance less than the pump wave-length can cause the formation of periodic polarization and population structures (gratings in time and space) in the pumped medium without a probe field. The magnitude of pump induced population grating can have a strong dependence on the relation between the pump field detuning and the polarization decay rate. The "interaction" between pump and probe induced polarization/population gratings through a dipole-dipole interaction mechanism causes the absorption line shape asymmetry. Under certain conditions, this asymmetry is revealed in increasing probe gain for the "red"-shifted (relative to pump) probe and suppressing the gain for the "blue"-shifted probe field when pump is "red"-shifted relative to the ensemble averaged resonant frequency. The theoretical results are consistent with experimental data for the probe gain or absorption as the function of frequency and the dependance of the gain on atomic density for sodium vapor when the pump laser is tuned near the D 2 line. Here the dependance of gain on particle density was explained in the terms of the long-range interaction between the atoms.

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“…(14) The matrix element of H is then where E(Ri~2) is the energy of the ith adiabatic state (with eigenvalue Y2 of j~,).…”

Section: /(21+ 1~ C(jlj" F~of~) Irjm ; Jl>= -~ D[~m(o --0 --R X] ~ mentioning

confidence: 99%

Quantum-mechanical theory including angular momenta analysis of atom-atom collisions in a laser field

DeVries

George

1978

Molecular Physics

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The problem of two atoms colliding in the presence of an intense radiation field, such as that of a laser, is investigated. The radiation field, which couples states of different electronic symmetry, is described by the number state representation while the electronic degrees of freedom (plus spin-orbit interaction) are discussed in terms of a diabatic representation. The total angular momentum of the field-free system and the angular momentum transferred by absorption (or emission) of a photon are explicitly considered in the derivation of the coupled scattering equations. A model calculation is discussed for the Xe + F collision system.

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Theory of collision effects on atomic and molecular line shapes

Cited by 90 publications

References 58 publications

Semiclassical expansion for systems with internal degrees of freedom

Semiclassical expansion for systems with internal degrees of freedom

Kinetics and Optical Properties of the Strongly Driven Gas Medium of Interacting Atoms

Quantum-mechanical theory including angular momenta analysis of atom-atom collisions in a laser field

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