Reaction of Gaseous HCNH₂⁺ and H₂CNH⁺ with a range of neutrals relevant to the atmosphere of Titan

Ions have been detected in many astrochemical environments but a region of focus is the ionosphere of Titan, where the CASSINI mass spectrometer detected many organic ions, triggering a rich gaseous chemistry [1]. We have measured reaction cross sections and branching ratios for the reaction of H₂CNH⁺ and HCNH₂⁺ ions that have been identified as potential contributors to the m/z 29 peak on Titan. Reacting neutrals are CH₄ as well as unsaturated hydrocarbons and nitriles. Data were collected using a tandem mass RF guide where ions were generated via VUV photoionization at the DESIRS beamline of the SOLEIL synchrotron [2].
We demonstrate that the two isomers show diverse and differing chemistries: in addition to charge transfer, proton-transfer and H-abstraction reactions, they undergo a range of more complex adduct reactions leading to the formation of C-C and C-N bonds.
[1] Vuitton et al., Icarus, 324, 120 (2019)
[2] D. Ascenzi et al. , Frontiers in Chemistry, 7, 537 (2019)