DEVELOPMENT OF A DETECTOR FOR ULTRATRACE NITROGEN IN ARGON USING LOW-PRESSURE, CAPILLARY GLOW-DISCHARGE MOLECULAR-EMISSION SPECTROPHOTOMETRY

A highly sensitive detector was developed for determining parts per bi llion of nitrogen in high-purity argon. The method is based on the spe ctrophotometric determination of the emission intensity from the nitro gen molecule excited in the lowest vibrational transitions of the elec tronic C-3 Pi(u) --> B-3 Pi(g) system. A capillary glow discharge tech nique was applied to excite nitrogen in an argon now at several Torr. The low-pressure, capillary glow discharge method offered high sensiti vity for detecting trace nitrogen in argon. The response of the detect or was proportional in the range of nitrogen concentrations from 0.1 p pb, which correspond to S/N = 3, to 100 ppm.