Dissociative recombination of CO₂⁺ and O₂⁺ (produced from CO₂⁺ reaction as well) can generate the oxygen atoms that travel fast enough to escape:
CO+
2 + e−
 ⟶ CO + O
CO+
2 + O ⟶ O+
2 + CO
O+
2 + e−
 ⟶ O + O

However, the observations showed that there are not enough fast oxygen atoms the Martian exosphere as predicted by the dissociative recombination mechanism.
Model estimations of oxygen escape rate suggested it can be over 10 times lower than the hydrogen escape rate.
Ion pick and sputtering have been suggested as the alternative mechanisms for the oxygen escape, but this model suggests that they are less important than dissociative recombination at present.
Dissociative recombination of CO₂⁺ and O₂⁺ (produced from CO₂⁺ reaction as well) can generate the oxygen atoms that travel fast enough to escape:
CO+
2 + e−
 ⟶ CO + O
CO+
2 + O ⟶ O+
2 + CO
O+
2 + e−
 ⟶ O + O

However, the observations showed that there are not enough fast oxygen atoms the Martian exosphere as predicted by the dissociative recombination mechanism. Model estimations of oxygen escape rate suggested it can be over 10 times lower than the hydrogen escape rate. Ion pick and sputtering have been suggested as the alternative mechanisms for the oxygen escape, but this model suggests that they are less important than dissociative recombination at present.
Atmosphere of Mars