Responses of OH (X2Π) and OH (A2Σ+) to high-energy electrons of dielectric barrier discharge in plasma-assisted burner flame

We examined the responses of OH(X2Π) and OH(A2Σ+) in a premixed CH4 flame to high-energy electrons produced by a dielectric barrier discharge. The density of OH(X2Π) did not respond to the pulsed production of high-energy electrons; however, we observed a pulsed increase in the density of chemically produced OH(A2Σ+). In addition, we observed that OH(A2Σ+) produced at the same time as high-energy electrons had a lower rotational temperature. We discussed possible key reactions in plasma-assisted combustion on the basis of the experimental observation showing the production of cold OH(A2Σ+).