In electronegative-electropositive gas mixtures plasma, at a total pressure varying in the range of ten to hundred Torr, was reported the appearance of a quasi-mochromatization effect of the emitted radiation. This radiation could be the result of the generation mechanisms at molecular level, which is the case of the excimer radiation but also at atomic level. Thus, in the last case, in (Ne+1%Ar/Xe+H 2 ) gas mixtures plasma in a dielectric barrier discharge (DBD), this effect consists in the reduction of the discharge emission spectrum practice at one single, strong spectral line, namely λ = 585.3 nm, as it is shown in the Figure 1. 575 600 625 650 675 700 725 750 0 2 4 6 8 10 12 614.3nm 585.3nm (Ne+1% Ar)+40% H 2 P tot =100 torr λ λ λ λ 1 λ λ λ λ 2 I(a.u.) λ λ λ λ(nm ) Figure 1 Emission spectrum of DBD discharge in (Ne + 1%Ar + 40%H 2 ) gas mixture at p tot =100 TorrThe present paper is concerned with the main characteristics comparative investigation of the principal reaction mechanisms involved in the quasi-monochromatization effect existence, namely the direct Harpoon reaction, in the case of the excimer radition, which appears as a result of the generation processes at molecular level and the resonant polar three-body reaction as a result of the generation processes at atomic level. Also, the paper points out the role and the importance of the metastable electronegative atoms in the appearance of the monochromatization -effect at atomic level [1], [2].