Experimental simulation of Titan's stratospheric photochemistry: benzene (C6H6) ices

Titan, often compared to the early Earth, is the only moon in the solar system to have a dense atmosphere, mainly composed of nitrogen and methane. In the upper part of the atmosphere (>1000 km), UV photons, photoelectrons, energetic ions and magnetospheric electrons induce the dissociation and the ionization of N₂ and methane. These reactions lead to the formation of complex organic molecules - including hydrocarbons such as benzene - and aerosols in the high atmosphere (an organic haze responsible for Titan’s brownish color), which are subject to different UV radiation classes depending on the altitude. Therefore, during their sedimentation toward the surface, these organic photoproducts are known to be modified. Once the tropopause is reached, molecules like benzene (C₆H₆) condense and evolve under long UV radiations to contribute to aerosol formation.