Abstract
A voltage modulation technique was applied to the high sensitivity measurement for a glow discharge spectrometry. The radiation emitted from the glow discharge plasma can be periodically varied by a cyclic variation in input voltage and can be selectively detected against predominant noises with a lock-in amplifier. As compared to a conventional detec-tion method, the signal-to-noise ratio was improved by a factor of 20-50. By this modulation spectrometry, quantitative detection of minor elements in some low-alloyed steels was achieved for the application to elemental analysis.
