Atmospheric Pressure Plasmas at the Liquid Interface

The use of non-equilibrium atmospheric pressure plasmas for medicinal and biological applications has shown great promise. Possibilities exist for potential cancer therapies as well as sterilisation and wound healing. A fundamental understanding of the plasma chemistry is important to the further development of these applications. Of particular importance are the chemical kinetics and energy transport mechanisms at the liquid interface. The aim of this work is to obtain measurements of the important reactive neutral species in this region in order to better understand and control the plasma chemical environment. Direct observation of free radicals is complex due to their very short lifetimes. Spin trapping is used to selectively convert unstable radicals to persistent ones, which are then detected by electron paramagnetic resonance (EPR) spectroscopy. The interaction between a kHz dielectric barrier discharge (DBD) plasma jet (operated using a helium feed gas and molecular gas admixtures) with liquids, gels and single layers of organic compounds are investigated and presented in this piece of work.