Absorption and emission line profile coefficients of multilevel atoms-I. Atomic profile coefficients

Ivan - Hubeny, J. Oxenius, E. Simonneau

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The line profile coefficients for absorption and emission appearing in the radiative transfer equation are formulated in terms of atomic line profile coefficients and velocity distribution functions. In order to derive the atomic profile coefficients of a multilevel atom, one defines generalized atomic redistribution functions that describe the correlations between photons involved in consecutive radiative transitions of the atom. Besides their dependence on the radiation field, the atomic line profile coefficients of a multilevel atom depend on the velocity distributions of the atoms in the various excitation states, in contrast to the case of a two-level atom where only the radiation intensity but not the velocity distributions affect the atomic emission profile. Closed expressions of the atomic profile coefficients in terms of generalized redistribution functions are obtained if stimulated emissions are neglected, and one is led to an iterative approximation scheme if stimulated emissions are taken into account. The possibility of a nonlocal character of the atomic profile coefficients is pointed out, and the effect of elastic, velocity-changing collisions with excited atoms is discussed. A major aim of this paper is to draw attention to the fact that ordinary redistribution functions that describe only the correlations between the absorbed and reemitted photons in the same spectral line are not sufficient to formulate the line profile coefficients of a multilevel atom.

Original languageEnglish (US)
Pages (from-to)477-493
Number of pages17
JournalJournal of Quantitative Spectroscopy and Radiative Transfer
Volume29
Issue number6
DOIs
StatePublished - 1983
Externally publishedYes

Fingerprint

Atoms
coefficients
profiles
atoms
Velocity distribution
Stimulated emission
velocity distribution
stimulated emission
Photons
Radiation
Radiative transfer
photons
Distribution functions
radiation distribution
radiative transfer
line spectra
radiant flux density
distribution functions
collisions
approximation

ASJC Scopus subject areas

  • Spectroscopy
  • Atomic and Molecular Physics, and Optics

Cite this

Absorption and emission line profile coefficients of multilevel atoms-I. Atomic profile coefficients. / Hubeny, Ivan -; Oxenius, J.; Simonneau, E.

In: Journal of Quantitative Spectroscopy and Radiative Transfer, Vol. 29, No. 6, 1983, p. 477-493.

Research output: Contribution to journalArticle

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AB - The line profile coefficients for absorption and emission appearing in the radiative transfer equation are formulated in terms of atomic line profile coefficients and velocity distribution functions. In order to derive the atomic profile coefficients of a multilevel atom, one defines generalized atomic redistribution functions that describe the correlations between photons involved in consecutive radiative transitions of the atom. Besides their dependence on the radiation field, the atomic line profile coefficients of a multilevel atom depend on the velocity distributions of the atoms in the various excitation states, in contrast to the case of a two-level atom where only the radiation intensity but not the velocity distributions affect the atomic emission profile. Closed expressions of the atomic profile coefficients in terms of generalized redistribution functions are obtained if stimulated emissions are neglected, and one is led to an iterative approximation scheme if stimulated emissions are taken into account. The possibility of a nonlocal character of the atomic profile coefficients is pointed out, and the effect of elastic, velocity-changing collisions with excited atoms is discussed. A major aim of this paper is to draw attention to the fact that ordinary redistribution functions that describe only the correlations between the absorbed and reemitted photons in the same spectral line are not sufficient to formulate the line profile coefficients of a multilevel atom.

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