Some studies examined lasing mechanisms and calculated the characteristics for active media that until recently did not lead to the making of NPLs, for example, active media using transitions of the 1st negative system of the CO+ molecule (A = 219 nm) [143, 144]. From calculations of the characteristics of a CO+ laser it follows that in the mixture He-CO-H2, (hydrogen is used to depopulate the lower laser levels) for q = 1-2 kW/cm3, it is possible to obtain quasi-CW lasing at A = 219 nm with rather high efficiencies: n = 3-4 % [143]; 0.7 % [144]. It should be noted that in the experiments of [145] on pumping a He-CO mixture at atmo­spheric pressure with an electron beam, stimulated radiation was registered at transitions of the CO+ molecule with A = 247 nm (1st negative system) and A = 395 and 421 nm (Baldet-Johnson system).

Authors of model [144] discussed the possibility of appearance lasing on the line of the O2 ion with A = 160 nm during excitation of the He-O2-H2 mixture by fission fragments and an electron beam. We could not establish the affiliation of this line with an electronic-vibrational transition of the O2 ion (see [146], for example). As noted in study [147], as a result of the charge-transfer process He^ + O2, there is selective populating of the state b4Xg~ of the O2 ion, from which the transitions of the first negative system of oxygen (500-850 nm) begin.