Atomic oxygen distribution in the interaction zone of a micro atmospheric pressure plasma jet and a surface.

As a reactive species atomic O finds successful use for surface treatments or in medical applications. To examine the distribution along treated substrates, two-dimensional two photon absorption laser induced fluorescence spectroscopy (TALIF) was used. Measurements of the atomic O density were performed in the effluent of a rf coupled micro atmospheric pressure plasma jet (COST-(μAPPJ) ) in the interaction zone of a metallic (Cu) surface with a He/O gasflow. To this end, the width of the atomic O profile in the effluent, the atomic O peak density in the maximum of the effluent and the atomic O density integrated over the laser axis across the effluent profile were examined. For the width a flow dependent broadening of the profile was asserted, where smaller flows resulted in a wider broadening in front of the surface. The investigation of the peak density yielded a longer life span of atomic O in comparison to the integrated density because of a smaller quenching influence from air inflow in the effluent center. Additionally, the integrated density made an increase in atomic O in front of a surface visible, at which smaller flows caused a higher percentage density increase. Furthermore, two-dimensional atomic O density distributions along the surface were shown. Schlieren imaging confirmed that atomic oxygen follows the Helium flow and laid the basis for transferring the TALIF results to other jet-surface-configurations.