Studies On The Emission Spectra Of Small Inorganic Gaseous Molecules Using Dielectric Barrier Discharge As Excitation Source

Dielectric barrier discharge (DBD) is a kind of gas discharge, in which high dielectric materials such as silica, ceramic and argon gas etc are first filled between the electrodes and then stable and homogeneous plasma is formed between the electrodes. Compared with conventional plasma sources, DBD can be easily obtained under the common atmospheric pressure with low power consumption (ca.10W). At the same time, the lower temperature plasma of DBD is helpful to avoid the decomposition of gaseous molecules, which is usually induced by conventional high temperature plasma, and make it a suitable exciatation source for gaseous molecules. Moreover, the equipment of DBD could be easily constructed with small size facilitating the miniaturization of analytical instruments. In recent years, more and more attentions have been focused on the miniaturization of emission spectroscopic analysis system using DBD as excitation sources.In this paper, the low-temperature plasma of DBD is used as excitation source for the studies of emission spectra of small inorganic gaseous molecules NH3and H2S. Plasma produced using various dielectric materials, such as alumina ceramic tube (i.d.1mm×75mm) and panel discharge chamber (40mm×10mm×1mm), with argon gas as carrier is used as the excitation source for target gaseous molecules. The effects of operating parameters including the DBD parameters, the flow-rate of carrier gas and the sample volume etc have been investigated. Under the optimal experimental conditions, the emission wavelength of326.24nm and365.06nm are selected as the quantitative wavelength for the determination of NH3and H2S, The limit of detection of NH3and H2S are deduced to be0.6mg m-3and1.4mg m-3respectively. The developed DBD are used for the determination of the content of NH3in toilet air and S2-in water samples. The content of NH3in toilet air is3.6mg m-3with a spiking recovery of94.7%. The spiking recovery for S2-in three water samples is in the range of94.8%～101%.