HIGH RESOLUTION INVESTIGATION OF THE ETHANE SPECTRUM AT 7 MICRON (1430 CM$^{-1}$)

Author Institution: Dipartimento di Chimica Farmaceutica e Tossicologia, Universita di Napoli Federico II , I-80131 Naples, Italy; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA; Service de Chimie Quantique et Photophysique, Universite Libre de Bruxelles, CP 160/09, 50 avenue F.D. Roosevelt, B-1050 Brussels, Belgium; Dept. of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320, USA; Science Directorate, NASA Langley Research Center, Hampton, VA 23681, USABuilding upon our previous contributions, we are re-investigating the ethane spectrum between 1330 and 1610 cm$^{-1}$. For this, spectral data were obtained at room and cold (130 K) temperatures with two Bruker Fourier transform spectrometers (at 0.002 cm$^{-1}$ resolution in Brussels and at 0.003 cm$^{-1}$ resolution in Pasadena). Over 3300 lines were assigned to $\nu_6$, $\nu_8$, $\nu_4+\nu_{12}$ and $2\nu_4+\nu_9$ cold bands, and one hot band ($\nu_4+\nu_8-\nu_4$). Note that $\nu_6$, $\nu_8$, $\nu_9$, and $\nu_{12}$ are near 1379, 1472, 823, and 1195 cm$^{-1}$, respectively, and $\nu_4$ is the torsional mode near 289 cm$^{-1}$. Our new analysis includes an improved implementation of the theoretical Hamiltonian needed to interpret the very complex spectral structures caused by numerous interactions between these 5 vibrational modes. From this, an empirical line list of positions and estimated intensities is being generated for planetary applications. \