Vibration-rotation spectra of hydrogen halides in rare-gas liquids:
Q-branch absorption
A. Medina, J. M. M. Roco, A. C. Hern�ndez, and S. Velasco
ETSII de Béjar,Universidad de Salamanca, 37700,
Béjar, Salamanca, Spain;
Departamento de Física Aplicada, Facultad de Ciencias, Universidad
de
Salamanca, 37008 Salamanca, Spain
Abstract:
Near-infrared spectra of HCl highly diluted in liquid Ar show intense
absorption in the P-R interbranch region, so-called Q-branch absorption.
In spite of its relevance for the shape of the bands, its physical origin
has been elusive to date. We employ molecular dynamics simulations to
study the influence of some physical effects that could contribute to
Q-branch absorption. We check that multipole-induced dipole induction
mechanisms are not quantitatively relevant in this spectral region.
We show that the particular characteristics of accurate HCl-Ar anisotropic
potentials and the peculiar hindered rotational motion they provoke
on the diatomic probe are essential to understand Q-branch absorption.
*Lecture presented at the European Molecular Liquids
Group (EMLG) Annual Meeting on the Physical Chemistry of Liquids: Novel
Approaches to the Structure, Dynamics of Liquids: Experiments, Theories,
and Simulation,Rhodes, Greece, 7-15 September 2002. Other presentations
are published in this issue, pp. 1-261.
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