This study focuses on the generation and loss of reactive oxygen species (ROS) in lowtemperature
atmospheric‐pressure rf (13.56MHz) He+O2+H2O plasmas, which are of
interest for many biomedical applications. Pure He+O2 plasmas are a good source of ozone,
singlet oxygen and atomic oxygen, with densities of these species increasing as oxygen
content increases1. He+H2O plasmas offer an interesting alternative to He+O2 plasmas as a
source of reactive oxygen species (ROS), and they produce significant amounts of hydrogen
peroxide, hydroxyl radicals and hydroperoxyl radicals, which increase with increasing water
content2. Admixtures of O2 and H2O lead to richer cocktails of ROS that combine all these
species
