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.
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.
Memory effects in speed-changing collisions and their consequences for spectral line shape
Abstract.The kinetic model accounting for speed-memory effects on the spectral line shape proposed in I [D. Robert, L. Bonamy, Eur. Phys. J. D 2, 245 (1998)] is extended for any density range, within the binary collision framework. The additional Doppler contribution requires to consider the 3D velocity-memory function instead of the 1D speed one, with distinct treatments for the velocity-orientation and velocity-modulus memory mechanisms. Both the collisional confinement narrowing of the Doppler distribution and the radiator speed-dependence of the collisional broadening and shifting parameters are thus conveniently taken into account. In the high density regime, this model leads to the same results as in I. At lower densities, it generalizes the very well-known hard and soft collision models for the Dicke narrowing of the Doppler distribution, but it also includes the second source of inhomogeneity tied to the speed-dependent collisional parameters and, concomitantly, the speed class exchanges. Numerical applications to H2-N2 and H2-Ar gaseous mixtures are in close agreement with experiments. This allows one to clearly analyze the specific role of speed and velocity memory effects on the line profile.
The politics of affect and emotion in contemporary Latin American cinema : Argentina, Brazil, Cuba, and Mexico
Between Neo-realist Sentimentality and Modernist Shock: New Latin American Cinema and Beyond Thrilling Histories: Questions of Genre and History Affecting Legacies: Contemporary Structures of Feeling Alien/Nation: Contemporary Youth in Film Emotional Investments: Global Networks and Transnational Affective Communities