Low-pressure OH radicals reactor generated by dielectric barrier discharge from water vapor

Hydroxyl (OH) radicals were generated by dielectric barrier discharge (DBD) from water vapor in a multi-pass cell with a volume of 8000 cm3. The cell was filled with the following water vapor at reduced pressure. The absolute OH number density was accurately determined by direct absorption spectroscopy using a tunable laser operating at 2.8 μm. The absolute OH number density was around 1012 molecules/cm3. Helium, methane, ethane, propane, and carbon monoxide were respectively introduced into the multi-pass cell to study their influences on the OH number density. The decay rate of OH number density was directly related to the reaction rates of the added gases. The low-pressure DBD OH multi-pass cell can be used as a reactor to further study the reaction kinetics associated with OH radicals.