The pulsed glow discharge as an elemental ion source

Abstract

A pulsed glow discharge, rather than a conventional constant dc voltage discharge, is used as an ion source for a quadrupole mass spectrometer. Both sputter yield and ion signal are enhanced by using the pulsed system because of an increase in the voltage necessary to maintain a constant average current at the cathode over the pulse period. Irregularities are seen in the pulse spectrum that appear as rapid surges in the ion signal for both sputtered and contaminant gas species. These peaks appear at the beginning of the pulse for gaseous species but are limited to the postpulse period for sputtered species. Differences in the signal forms allow for the discrimination against selected types of ion signals by using narrow data collection gates placed over different portions of the pulse period.

Pulsed r.f.‐glow‐discharge time‐of‐flight mass spectrometry for fast surface and interface analysis of conductive and non‐conductive materials

“…Using ToF mass spectrometers has the advantage of a simultaneous detection of all masses of interest, which makes the technique suitable for the analysis of thin interfaces, thin films and surfaces. 4 The interest in pulsed GD coupled to a mass spectrometer has steadily increased since the publication of the initial work of Harrison and co-workers, exploring the pulsed operation in combination with both time-of-flight mass spectrometer (ToF-MS) 5 and optical emission spectrometers (OES). 6 Most work recently published on GD-ToF-MS and OES are studies on pulsed direct current discharges.…”

Powering the analytical glow discharge

“…In addition, the higher current during the pulse creates a plasma chemistry that may yield greater efficiency of excitation and ionization. We have used pulses in the millisecond regime and found a useful sputter enhancement [19], but that effect alone is not necessarily sufficient to justify a pulsed power supply and gated detection system. More interesting has been the temporal advantage [20,21] to be gained, by which certain interference species may be discriminated against.…”

“…One method of extending glow discharges to higher power levels is by the use of pulse techniques. We first used pulsed glow discharges over 20 years ago [18] and have continued the studies in a variety of experiments [19,20]. The principle of plasma enhancement through pulsed methods is easily seen in Fig.…”

Application of Dual-step Pulse Voltage to the Excitation Source for Improving the Depth Profiling in Glow Discharge Optical Emission Spectrometry

“…The pulsed discharge can restrict the sputtering rate and minimize thermal damage of the sample surface, in order that one can analyze various specified samples, such as a ultra-thin layer and an organic film. 1,5) Nowadays, commercialized apparatuses for GD-OES have normally had a pulsed discharge mode. Review…”