Vacuum ultraviolet emission from microwave plasmas of hydrogen and its mixtures with helium and oxygen

The vacuum ultraviolet (VUV) and ultraviolet (UV) emission (112 nm≤λ≤300 nm) from hydrogen‐containing microwave plasmas have been investigated, in particular the influence of plasma parameters such as gas composition, pressure, and microwave power. Helium–hydrogen plasma emits a very intense hydrogen Lyman α radiation at 121.5 nm, which is up to 40 times more intense than other lines in the spectrum. Hydrogen–oxygen plasma displays an emission which, within a selected range of the plasma parameters, resembles the absorption of molecular oxygen. We briefly discuss the usefulness of these emissions for investigating the UV photochemistry of polymers.