A near-wing correction to the quasistatic far-wing line shape theory

Journal Article · Tue Feb 15 04:00:00 EST 1994 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.466502· OSTI ID:5191417

Ma, Q ^[1]; Tipping, R H ^[2]

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1. Department of Applied Physics, Columbia University and Institute for Space Studies, Goddard Space Flight Center, New York, New York 10025 (United States)
2. Department of Physics Astronomy, University of Alabama, Tuscaloosa, Alabama 35487 (United States)

A new representation is introduced in which the rapidly varying time-dependent part of the time displacement operator can be factored out and the remaining part, which varies with time more slowly, can be expanded in the usual perturbational fashion. The lowest order approximation leads to the far-wing quasistatic line shape theory developed previously, whereas the next order approximation, related to the noncommutation of the Liouville operators describing the unperturbed absorber and bath molecules and the interaction between them, leads to a near-wing correction. Explicit expressions are derived for both the corrections to the spectral density and the statistical band-average line shape function assuming an anisotropic dipole--dipole interaction. Detailed computations for the case of self-broadened H[sub 2]O are carried out for the line-shapes and the corresponding absorption coefficients for several temperatures and for frequencies to 10 000 cm[sup [minus]1]. From these results, we conclude that the near-wing corrections generally increase the line shape function between 10 and 200 cm[sup [minus]1], and that this increase is more important for lower temperatures than for higher ones. This in turn leads to increased absorption nearer the band centers, especially for lower temperatures, and thus to improved agreement between theory and experiment.

• OSTI ID: 5191417
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 100:4; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664100* -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
CORRECTIONS
DIPOLES
ELEMENTS
EQUATIONS
FLUIDS
FREQUENCY DEPENDENCE
GASES
HYDROGEN COMPOUNDS
LINE WIDTHS
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
MULTIPOLES
NITROGEN
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SPECTRA
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
VAPORS
WATER