ROTATIONAL PERTURBATIONS IN THE SCHUMANN-RUNGE BANDS NEAR THE DISSOCIATION LIMIT

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1997

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Ohio State University

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Predissociation in the Schumann-Range bands of molecular oxygen plays an important role in the production of atmospheric $ozone^{h}$. However, the region of the Schumann-range bands near the dissociation limit $(\nu^{\prime} = 18 - 22)$ has only been partially analysed in the past. This has been due to the difficulties associated with obtaining accurate intensity and width measurements with spectrographic techniques, and the presence of ``main” and ``extra” lines associated with rotational perturbations. Our use of the non-linear optical technique of four-wave difference-frequency mixing (FWDFM) has enabled this region of the Schumann-Range bands (from 175-178nm) to be studied in unprecedented detail, with sub-Doppler resolution inabsorption. Recent measurements using FWDFM have enabled analysis of the $\nu^{\prime} = 16 - 18$ bands, with interpretation of the perturbations present in the region. The current investigation involves the study of those lines from $\nu^{\prime} = 19 - 22$. Preliminary analysis of the $\nu^{\prime} = 19$ band rotational lines confirms the presence of perturbations in the $F_{3}$ levels, possible caused by interactions with the $C^{\prime}\ ^{3}\Pi$ state. Results will be presented here on the recent findings in this region.

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$^{h}$M. Nicolet, J. Geophys. Res. 89, 2573 (1984) $^{i}$ P. Brix and G. Herzberg, Can. J. Phys. 32, 110, (1954) $^{j}$B. R. Lewis, P.M. Dooley, J. P. England, K. Waring, S. T. Gibso, K. G. H. Baldwin and H. Partridge, Phys. Rev. A 54, 3923, (1996).
Author Institution: Research School of Physical Sciences and Engineering, The Australian National university

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