The transition probabilities for induced emission and absorption of electromagnetic radiation by an excited atom interacting, in addition to the radiation field, with a system of "perturbers" (in single, binary, and completed encounters) are evaluated. It is found that Dirac's result $\frac{{W}_{\mathrm{ind}}}{{W}_{\mathrm{abs}}}=\frac{({\overline{n}}_{l\ensuremath{\sigma}}+1)}{{\overline{n}}_{l\ensuremath{\sigma}}}$ must be modified by a factor $\frac{{(1\ensuremath{-}\ensuremath{\alpha}n)}^{2}}{{(1+\ensuremath{\alpha}n)}^{2}}$, where $\ensuremath{\alpha}$ is related to the interaction potential of the emitter-perturber system as well as to the level structure of the "colliding" atoms, and $n$ is the perturber number density.The transition probabilities for induced emission and absorption of electromagnetic radiation by an excited atom interacting, in addition to the radiation field, with a system of "perturbers" (in single, binary, and completed encounters) are evaluated. It is found that Dirac's result $\frac{{W}_{\mathrm{ind}}}{{W}_{\mathrm{abs}}}=\frac{({\overline{n}}_{l\ensuremath{\sigma}}+1)}{{\overline{n}}_{l\ensuremath{\sigma}}}$ must be modified by a factor $\frac{{(1\ensuremath{-}\ensuremath{\alpha}n)}^{2}}{{(1+\ensuremath{\alpha}n)}^{2}}$, where $\ensuremath{\alpha}$ is related to the interaction potential of the emitter-perturber system as well as to the level structure of the "colliding" atoms, and $n$ is the perturber number density.

Physical Review LettersNov 16, 19700 citations

Absorption and emission of radiation in the region of an avoided level crossing

M. J. O’Callaghan, Alan Gallagher, Theodore D. Holstein

The spectrum for absorption and emission of radiation by colliding atoms or a diatomic molecule is calculated for spectral regions dominated by an avoided level crossing. Example processes are absorption during an atom-atom collision with separation to either crossing atomic state, total absorption to both crossing states, and spontaneous emission during a collision with either state initially populated. Absorption and emission by bound diatomic molecules (including photodissociation) is described by the theory, and as an example it is applied to the ${\mathrm{Cs}}_{2}$ A-X band. Spectra due to single-velocity and impact-parameter collisions, as well as thermal and impact-parameter averages, are given. The shapes of the resulting spectra are parametrized by the interaction strength (or excitation transfer probability) between the crossing levels and the slopes of the ground- and excited-state potentials (assumed constant) in the region of the level crossing. The theory is applied to two observations of such regions that have been reported. We conclude that measurements of spectra in the region of level crossing is a very powerful diagnostic of the potentials and transfer probability in the level-crossing region, which is responsible for most inelastic atom-atom energy-transfer processes.The spectrum for absorption and emission of radiation by colliding atoms or a diatomic molecule is calculated for spectral regions dominated by an avoided level crossing. Example processes are absorption during an atom-atom collision with separation to either crossing atomic state, total absorption to both crossing states, and spontaneous emission during a collision with either state initially populated. Absorption and emission by bound diatomic molecules (including photodissociation) is described by the theory, and as an example it is applied to the ${\mathrm{Cs}}_{2}$ A-X band. Spectra due to single-velocity and impact-parameter collisions, as well as thermal and impact-parameter averages, are given. The shapes of the resulting spectra are parametrized by the interaction strength (or excitation transfer probability) between the crossing levels and the slopes of the ground- and excited-state potentials (assumed constant) in the region of the level crossing. The theory is applied to two observations of such regions that have been reported. We conclude that measurements of spectra in the region of level crossing is a very powerful diagnostic of the potentials and transfer probability in the level-crossing region, which is responsible for most inelastic atom-atom energy-transfer processes.

Physical Review ANov 1, 198519 citations

Collisions of Highly Excited Atoms

R. F. Stebbings

Advances in atomic and molecular physicsJan 1, 19798 citations

Inelastic scattering of light and transitions of colliding atoms to bound molecular states

A. M. Bonch-Bruevich, Sergey G. Przhibel'skii, V. A. Khodovoǐ +1 more

A study is made of the influence of photon absorption (emission) processes on the dynamics of collisions between two atoms. Under certain conditions the radiation field can transfer colliding atoms to a bound molecular state. The main contribution to these processes is made by atoms colliding with relative velocities and impact parameters which ensure that these atoms spend a long time near each other (quasifinite motion). The appearance of quasifinite states in the absorption spectra of Rb and Cs vapors is reported and a determination is described of the matrix elements of the transitions from these states to a bound molecular state.A study is made of the influence of photon absorption (emission) processes on the dynamics of collisions between two atoms. Under certain conditions the radiation field can transfer colliding atoms to a bound molecular state. The main contribution to these processes is made by atoms colliding with relative velocities and impact parameters which ensure that these atoms spend a long time near each other (quasifinite motion). The appearance of quasifinite states in the absorption spectra of Rb and Cs vapors is reported and a determination is described of the matrix elements of the transitions from these states to a bound molecular state.

Soviet Journal of Quantum ElectronicsApr 30, 19762 citations

Collisions between excited atoms

J. Pedersen

Jan 1, 19940 citations

n

is the perturber number density.

{\mathrm{Cs}}_{2}

A-X band. Spectra due to single-velocity and impact-parameter collisions, as well as thermal and impact-parameter averages, are given. The shapes of the resulting spectra are parametrized by the interaction strength (or excitation transfer probability) between the crossing levels and the slopes of the ground- and excited-state potentials (assumed constant) in the region of the level crossing. The theory is applied to two observations of such regions that have been reported. We conclude that measurements of spectra in the region of level crossing is a very powerful diagnostic of the potentials and transfer probability in the level-crossing region, which is responsible for most inelastic atom-atom energy-transfer processes.