| The optical emission spectroscopy has been applied to study the emission spectra from N2, NO/N2, O2/N2 and NO/O2/N2 plasmas with dielectric barrier discharge (DBD) at atmospheric pressure . The experimental results are as follows:1. The emission spectra of N2 in DBD plasma has been measured. The lines attributed to N2(C3âˆu-B3âˆg+) were abtained. Excited nitrogen atom was detected in 600 900 nm .The relationship between the intensity of N2(C3âˆu-B3âˆg+) and the gas flowrate was measured. The intensity of N2(C3âˆu-B3âˆg+) decreased with the increasing of the gas flowrate.2. The emission spectra of NO/N2, O2/N2 and NO/O2/N2 in DBD plasmas produced by ac power source with frequency of 50 Hz and 5 kHz respectively was measured. The vibrational band of NO(A 2∑+-X2âˆ) was detected. The concentrations of the gas mixtures were measured by using chemifluorescences NOx analyzer, N2O infrared absorbed gas analyzer and MS. It was discussed that N(4S) and N2(A) were responsible for the nitrogen oxides conversion in nonthermal nitrogen plasma.3. Choosing CH4, C2H4 and C2H2 which were often used to study the removal of NOx in the presence of excess oxygen, we measured the emission spectra of CnHm/He, CnHm/N2, NO/CnHm/N2, NO/CnHm/O2/N2 (CnHm= CH4, C2H4, C2H2) in DBD plasma. The lines of CH(A2â–³-X2âˆ) (0, 0), CN(B2∑+-X2∑+) (0, 0) and C2(A3âˆg-X3âˆu) (0, 0) were detected. The effect on the NOx removal of hydrocarbons in DBD plasma was analyzed.
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