Influence of electrophilic species on the lower ionosphere of Titan

The galactic cosmic rays induced ionosphere of Titan is studied from 0 to 7 0 km. We resent here a new model developed for calculating the concentratio n of cations, anions, and electrons depending on the mixing ratio of electr ophilic species present in the atmosphere of Titan. The existence of neutra l species in which electrons can be attached by the three-body process prod uces anions and, depending on the abundance of electrophilic specie, reduce s, even very strongly, the concentration of electrons. We also discuss the effect of the electron detachment of negative ions by absorption of solar r adiation, which could produce a decrease in the anions density and, consequ ently, an increase in the electron density.