Characteristics of the transient signal from pulsed glow discharge plasma for atomic emission analysis

This review described a noticeable feature of pulsed radio-frequency-driven glow discharge plasma for atomic emission spectrometry. The temporal response of the emission signal, generated by the pulsed discharge, comprised a sharp pre-peak and the subsequent plateau portion having smaller emission intensities each for the discharge pulse, in which the intensity of the pre-peak was 10–20 times as large as the plateau-stage intensity, depending on the discharge parameters. Suggested mechanisms for this phenomenon were introduced from several published papers, which were based on a temporal variation in a degree of self-absorption during a pulse duration, on generation of gas pressure wave, or on a transient increase of the discharge current at the initial edge of a pulse which thus elevated the gas temperature. It was also mentioned that such emission characteristics could be utilized to obtain better analytical performance in the optical emission spectrometry. A detection method, associated with the introduction of pulsed bias current, was effective for controlling the emission response from the pulsed plasma, because it totally elevated the emission intensity of the plateau portion rather than the pre-peak with little change in the background level.