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

Abstract

Building 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. \\