Photochemical sources of non-thermal neutrals for the exosphere of Titan

Abstract

Photochemical sources of non-thermal neutrals for the exosphere of Titan are evaluated. Non-thermal atom and molecule production for a number of neutral species results from the ionospheric chemistry. Neutral thermosphere and ionosphere density profiles and the chemical reaction scheme presented by Keller et al. (J. Geophys. Res. 97, 12117, 1992) are used to calculate non-thermal neutral production rates for 19 species with masses ranging from 13 to 65 amu. The number of chemical processes included in this analysis was 47, although most turn out to be rather unimportant. Escape rates for different species are also estimated. The estimated global atmospheric loss of nitrogen atoms, in any form, is S N = 2.5 × 10 25 s −1. The estimated global atmospheric loss of carbon atoms, in any form, ranges from S C = 1.7 × 10 25 to 4 × 10 25 s −1, depending on the assumptions made, with the smaller value being more likely.