Interaction of an Open-To-Air Helium Plasma Jet, Produced by Sub-Microsecond Discharges, With a Polystyrene Surface

This study investigates the effects of an open-to-air helium plasma jet, generated by sub-microsecond discharges, on polystyrene (PS) surfaces positioned at distances of 1 and 10 mm from the nozzle. Optical emission spectroscopy revealed that at 1 mm the plasma spectrum is dominated by N₂⁺ emission, while at 10 mm N₂ emission prevails. Surface analysis showed that at 1 mm PS surfaces developed micro- and nanostructures with varying compositions, particularly in the outer regions, while at 10 mm the surface exhibited a uniform nanostructure distribution. X-ray photoelectron spectroscopy and X-ray diffraction analyses indicated the incorporation of oxygen and nitrogen species and suggested the formation of functionalized graphene/graphite oxide microstructures.