Photoabsorption of hydrocarbons in Titan's atmosphere

Abstract

Titan, the largest satellite of the planet Saturn, has a thick atmosphere which consists of nitrogen (N₂) and methane (CH₄). In 2004, the Cassini-Huygens mission observed the occultation of two stars through the atmosphere of Titan and measured ultraviolet (UV) absorption spectra. Through these spectra it was possible to identify the molecular species contained in this environment. In the present work, we have simulated a spectrum of this atmosphere using some molecules such as CH₄, C₂H₂, C₂H₄, C₂H₆, C₄H₂, and C₆H₆. Our cross sections data were experimentally obtained using the electron energy-loss technique, where the electron energy-loss spectra, measured high incident energies and in small scattering angles, are similar to photoabsorption spectra. The comparison of our synthetic spectrum with that measured by Cassini shows that this method is very efficient for identifying molecules as well as estimating abundances.