Energetics of Reactions in a Dielectric Barrier Discharge with Argon Carrier Gas: II Mixtures with Different Molecules

A large research reactor for performingdielectric barrier discharge (DBD) experiments at atmospheric pressure (AP) has been used with argon (Ar) carrier gas under constant plasma conditions (f = 20 kHz, V-a(f) = 8kV(p-p) = 2.8 kV(rms)). Various permanent gases (H-2, O-2, N-2, light hydrocarbons) and some heavier organic molecules were introduced as reactive "dopant'' flows, F-d, at % concentrations in the F = 10 standard liters per minute (slm) flow of argon. We have earlier perfected and reported a method for measuring E-g, the energy dissipated per cycle of the applied a.c. voltage, and Delta E-g, the energy difference with and without reactive dopant in the Ar flow. The latter and F-d permit calculation of E-m, the energy absorbed from the plasma by each dopant molecule. Plots of E m versus F d and 1/F-d yield much valuable information about excitation, fragmentation, and polymerization in the DBD plasma environment. Optical emission (OES) and Fourier-transform infrared (FTIR) spectroscopies help to further enhance and complement interpretation of measured data.