title: A pure H2O isolated line-shape model based on classical molecular dynamics simulations of velocity changes and semi-classical calculations of speed-dependent collisional parameters.
abstract: It is well known that the Voigt profile does not well describe the (measured) shapes of isolated lines. This is due to the neglect of the intermolecular collision-induced velocity changes and of the speed dependence of the collisional parameters. In this paper, we present a new line profile model for pure H(2)O which takes both of these effects into account. The speed dependence of the collisional parameters has been calculated by a semi-classical method. The velocity changes have been modeled by using the Keilson-Storer collision kernel with two characteristic parameters. The latter have been deduced from classical molecular dynamics simulations which also indicate that, for pure H(2)O, the correlation between velocity-changing and state-changing collisions is not negligible, a result confirmed by the analysis of measured spectra. A partially correlated speed-dependent Keilson-Storer model has thus been adopted to describe the line-shape. Comparisons between simulated spectra and measurements for four self-broadened lines in the near-infrared at various pressures show excellent agreements.
authors.affiliation: Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA, CNRS UMR 7583), Université Paris-Est Créteil, 94010 Créteil Cedex, France.
authors.forename: N H
authors.initials: NH
authors.lastname: Ngo
authors.forename: H
authors.initials: H
authors.lastname: Tran
authors.forename: R R
authors.initials: RR
authors.lastname: Gamache