Knowledge Bank

A low temperature absorption cell has been used to obtain spectra between 100 and 300 Kelvin of planetary gases. These spectra were recorded with our Doppler-limited diode laser spectrometer and with the 1-m FTS located at the McMath Solar Telescope at the National Solar Observatory, operated at $0.0025cm-1$ resolution. We undertook an investigation of the spectrum of ethane, propane, and ethylene under $H2$-broadened conditions at temperatures appropriate to the outer planets. A modified confocal etalon facilitated precise measurement of line positions. We will discuss these experiments, the basic results, and the implications for planetary modeling.