Ion-molecule chemistry in Titanʹs ionosphere

A summary is presented of the information available from laboratory studies of ion-molecule reactions that is relevant to the chemistry occurring in Titanʹs ionosphere. Reaction information from the literature has been collated and many new reactions have been measured, including some ion-atom reactions. The sequences of ion-neutral reactions can lead to a rapid increase in ion size. How this increase may lead to aerosol production at the base of the ionosphere is briefly discussed. Laboratory observations of extremely rapid termolecular ion-neutral association reactions indicate that these association reactions are viable contribution to the ion chemistry at the base of Titanʹs ionosphere.