The Role of VUV Radiation in the Inactivation of Bacteria with an Atmospheric Pressure Plasma Jet

Abstract

Abstract A modified version of a microscale atmospheric pressure plasma jet (µ‐APPJ) source, so‐called X‐Jet, is used to study the role of plasma‐generated VUV photons in the interaction of bacteria. The new jet geometry allows effective separation of reactive particles (O atoms or O 3 molecules) from the plasma‐generated photons. The measurements of the size of inhibition zones formed in the layer of vegetative Escherichia coli bacteria, VUV emission intensity, and the mass spectrometry measurements show that photochemistry in the gas phase followed by photochemistry products impacting on bacteria is more effective in bacterial inactivation than direct VUV radiation damage. Protonated water cluster ions are detected indicating that water impurity has to be considered carefully. The combination of the presence of water cluster ions and O 2 molecules at the surface leads to the strongest effect. Additionally, the interaction of plasma‐generated VUV photons with the effluent of the He/O 2 plasma, but not with ground state O 2 , leads to faster inactivation of bacteria, most probably due to enhanced formation of O and O 3 . magnified image