2004 Volume 44 Issue 1 Pages 108-114
The application of a pulsed voltage to a Grimm-style glow discharge lamp was investigated to control the sputtering rate in d.c. glow discharge optical emission spectrometry. This purpose is to reduce the sampling depth so that thin film-like samples can be measured with a better spatial resolution and a better analytical precision. While the sputtering rate decreases by using a pulsed voltage due to the reduction in the effective discharge power, the emission signals from the glow discharge plasma are modulated by a cyclic variation of the discharge voltage so that only the desired signals can be detected without any noises with a lock-in amplifier. Whereas the sputtering rate could be more than 50% reduced when the duty ratio of the pulsed voltage was down to 20% compared to the rate in the corresponding continuous discharge, the emission intensities could be estimated with much better signal-to-noise ratios.
