Observation of OH Radical Reactions with Atomic Hydrogen in He/H2O Plasmas by Laser-Induced Fluorescence Spectroscopy

A novel atmospheric pressure plasma device that generates atomic hydrogen has been developed. The reaction of OH radicals with atomic hydrogen supplied from the device was investigated in a He/H2O mixture at a pressure of 530 Torr by laser-induced fluorescence (LIF) spectroscopy. OH radicals were generated using a dielectric barrier discharge (DBD) plasma and excited to A2Σ+(v'=1) from X2Π(v''=0) by a frequency-doubled dye laser (282 nm). When the device was operated, OH-LIF intensity was reduced near the DBD plasma. The spatial density profile of the OH radicals was also obtained when the device was turned on and off. The reaction mechanism was briefly discussed.