Spectroscopic Investigations on OH Radicals Generated in He/Water and Air/Water Mixtures by an Atmospheric Pressure Surface Discharge Micro Plasma Device

We report the optical spectroscopic study on OH radicals generated by a surface discharge micro plasma device in atmospheric pressure He/water and air/water under the several experimental conditions. Strong emission bands of OH radicals were observed in He/water and the intensity showed the super-linear dependence on the applied voltage. However, the emission was not confirmed in air/water because of the interference by N$_{2}$ emissions. Based on these results, generation and annihilation processes of excited OH radicals in both He/water and air/water mixtures are briefly discussed.