Improved line-broadening coefficents for asymmetric rotor molecules with application to ozone lines broadened by nitrogen

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Journal of Quantitative Spectroscopy and Radiative Transfer




A procedure for obtaining atom-atom intermolecular potentials from the two-center expansion using symbolic manipulations in FORTRAN and MATHEMATICA on a computer is described. The atom-atom potential for an XY2 molecule (C2v symmetry) and a linear, AB, molecule with the XY2 molecule positioned in the molecule-fixed axes in two different orientations (representations), labeled IIR and IIL, are calculated. It has been found that the previous development of the atom-atom potential in the IIR representation is incorrect and leads to a mixed formulation with electrostatic terms in the IR and atom-atom terms in the IIIL representation. Broadening-coefficient calculations presented here show that when the correct potential is used anomalous oscillations in the Ka? = 1 transitions for O3 broadened by N2 disappear. Further investigation has shown that the variations can be associated with particular quantum state symmetries. Improved agreement with the experimental measurements is observed.