The role of hydrocarbons in the lonospheres of the outer planets

The role of hydrocarbons as a possible sink for H⁺ and H₃⁺ ions in the lower ionosphere of the outer planets is examined. Calculations indicate that H⁺ and H₃⁺ are efficiently converted to hydrocarbon ions on reaction with methane. The terminal ions, CH₅⁺ and C₂H₅⁺ are rapidly neutralized in dissociative recombination with electrons. Extreme ultraviolet photolysis of hydrocarbons as a potential additional source of lower elevation ions in investigated.