The dielectric barrier discharge — a powerful microchip plasma for diode laser spectrometry

The dielectric barrier discharge plasma is presented as a powerful microchip source for analytical spectrometry. The dielectric barrier discharge is characterized by small size, low electric power (<1 W), low gas temperature (approx. 600 K) and excellent dissociation capability for molecular species, such as CCl2F2, CClF3 and CHClF2. It has been used here in the plasma modulation diode laser absorption spectrometry of excited chlorine and fluorine in noble gases as well as in air/noble gas mixtures. The analytical figures of merit of diode laser absorption spectrometry obtained with the dielectric barrier discharge are comparable with the results found earlier with dc and microwave induced plasmas of larger size with much higher plasma powers. Detection limits of 400 ppt and 2 ppb for CCl2F2 in He were found using the Cl 837 nm and the F 685 nm line, respectively.