ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We have derived symmetry-adapted expressions for the dipole moments of pairs of D∞h molecules interacting at long range, in a form useful for line shape analyses of collision-induced rototranslational spectra. Our results are complete to order R−7 in the intermolecular separation R. In addition to quadrupolar and hexadecapolar induction effects, results to this order include induction due to nonuniformities in the local field acting on a molecule (E-tensor induction), back induction, and polarization due to dispersion forces. The dispersion terms are computed within our recently developed reaction field model, from which we have obtained accurate integral expressions for the dipole coefficients, and approximations in terms of static susceptibilities and dispersion energy coefficients. For H2⋅⋅⋅H2, H2⋅⋅⋅N2, and N2⋅⋅⋅N2, numerical results for the dipole coefficients are tabulated. While quadrupolar induction dominates the long-range dipole, other induction effects are evident in the far-infrared collision-induced spectra. Over the range of validity of the model, E-tensor induction, back induction, and dispersion effects are generally smaller than hexadecapolar induction, but appreciable. The magnitudes of the dipole coefficients and the orientation dependence of each polarization mechanism determine its contributions to the observed collision-induced absorption spectra.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.453698
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