Production of dihydrogen was also detected by QMS, Fig. . The m/z = 2 signal, corresponding to H2 + , is seen to spike with the plasma discharge, decrease during the ferrocene pulse and return to the base line when the chamber is purged. The base line is not horizontal, suggesting that the purge time used for this experiment was too short. The lack of H emission signal using the OES could be due to an overlap between molecular N2 (SPS, 560 -700 nm) and the most intense H emission line (Hα = 656 nm). Reactions generating H2 and H are likely plenty but for an example, it has been found that electron impact dissociation of C2H2 resulting in H requires an energy of ≥ 7.5 eV, making the reaction feasible under present discharge conditions and hydrogen in the plasma volume probable. This is also supported by the strong emission line at 336.7 nm, which has an excitation energy of 11.0 eV.