Observation of NO_x species in a N₂/O₂/H₂O microwave discharge plasma: A laboratory simulation of Earth's atmosphere

Abstract

[1] During studies on the identification of the principal species produced in an N 2 /O 2 / H 2 O microwave discharge plasma, we succeeded in detecting the presence of NO x species, including NO 2 , in the gas phase. The Li + ion adduct mass spectra of the discharge plasma, obtained by means of a direct sampling system, clearly showed various peaks, giving direct evidence that in addition to the familiar NO and N 2 O species, significant amounts of gas-phase neutral NO 2 , NO 3 , HNO 2 , and HNO 3 were produced and detected in the N 2 /O 2 /H 2 O plasma. The influence of certain discharge variables on the yield and concentration of NO x Li + was investigated also. Comparison of the present results with field observations of Earth's atmosphere demonstrated that laboratory simulation experiments can yield species comparable to the reactive nitrogen oxide species found in the troposphere.