The reaction of nitrogen traces in plasmas with polymer surfaces

Trace amounts of nitrogen in argon plasmas and in sulfur dioxide plasmas result in the incorporation of nitrogen in the surface of polymers like polyethylene. In vacuum systems with a base pressure in the microbar range the main sources of the nitrogen are leaks and the desorption from the reactor walls. Impurities of the process gas can contribute, too. There is strong evidence, that the nitrogen is first oxidized to nitric oxide which then recombines with radicals at the polymer surface.