Knowledge Bank

Observational Infrared spectroscopy of planetary atmospheres presently employs instrumentation capable of spectral resolution equaling that of any technique available in thelaboratory. The $CO2$ laser heterodyne spectrometer has been used to observe planetary spectra at resolutions of $10-4cm-1$. The recently reported detection of stratospheric ethane on Jupiter near 12$\mu$m using infrared laser $heterodyning1$ required a Coordinate laboratory effort to provide line parameters from diode laser spectra. A diode laser spectrometer was used to determine individual frequencies and strengths for lines in the $\nu g$ band of ethane which, might be observed using the hyterodyne technique. Lines of ethane in the $12\mu$m region not belonging to $\nu g$ were also identified. This study is part of a more general $analysis2$ of $\nu g$ using diode laser and FTS $spectra.2$ The present configuration of the diode laser spectrometer includes several innovations not described previously. Techniques for measuring line frequencies and strengths will be presented. Confocal etalons of 50 and 2.5 cm length have been evaluated far use in calibration and spectral of diode laser output; the longer etalon provides a fringe pattern with 150 MHZ free-spectral-range andfringe widths limited by the laser output width, A method for rapid sweep-integration of second derivative spectra also has been $developed.1$T. Kostiuk, M. J. Mumma, F. Espenak, D. Deming, D. E. Jennings, and W. Maguire, Ap. J. 265. 564(1983) $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$J. Susskind, D. Reuter, D. E. Jenings, S. J. Daunt, W. E. Blass, and G. W. Halsey, J. Chem. Phys. 77. 2728 (1982); S. Daunt. A. Atakan, W. Blass. G. Halsey, D. Jennings, D. Reuter, J. Susskind, and J. Brault, submitted (1983).