Production of nitrogen oxides by lightning and coronae discharges in simulated early earth, venus and mars environments Original Research Article

We present measurements for the production of nitrogen oxides (NO and N2O) in CO2-N2 mixtures that simulate different stages of the evolution of the atmospheres of the Earth, Venus and Mars. The nitrogen fixation rates by two different types of electrical discharges, namely lightning and coronae, were studied over a wide range in CO2 and N2 mixing ratios. Nitric oxide (NO) is formed with a maximum energy yield estimated to be ∼1.3×1016 molecule J−1 at 80% CO2 and ∼1.3×1014 molecule J−1 at 50% CO2 for lightning and coronae discharges, respectively. Nitrous oxide (N2O) is only formed by coronae discharge with a maximum energy yield estimated to be ∼1.2×1013 molecule J−1 at 50% CO2. The pronounced difference in NO production in lightning and coronae discharges and the lack of formation of N2O in lightning indicate that the physics and chemistry involved in nitrogen fixation differs substantially in these two forms of electric energy.