The flowing afterglow of the N2-O2 discharge as a means of decontaminating/sterilising through UV irradiation: Summary of the research achieved and recent results

The plasma systems for disinfection/sterilization that we have been working on are mainly based on UV irradiation while most plasma “sterilisers” are calling on ions and radicals. In the latter case, inactivation generally proceeds from erosion of the microorganisms while, in the former case, the UV photons create enough lesions to the DNA genetic material to prevent its repair. Inactivation of microorganisms through UV photons in the afterglow is, however, much slower than in the discharge itself. The UV photons stem from NO excited molecules, which are generated following the interaction of N and O atoms, in the flowing afterglow, which are coming from the dissociation of N₂ and O₂ in the (microwave) discharge. Since the N and O atoms can diffuse into crevices before joining into NO molecules, there is no limited accessibility of the UV photons as with a UV lamp. The NO_γ molecular system shows band heads that cover almost continuously the 180-350 nm range.