Reactive glow discharges: comparison of steady-state versus pulsed operation

Abstract

In this work we compare glow discharges using traditional, inert gases and alternative reactive gases. More specifically, argon is systematically replaced by nitrogen (or oxygen) at increasing levels, culminating in a plasma completely sustained by nitrogen (or oxygen). To decouple the reactive plasma processes from potentially reactive surface reactions, we employed gold as a non-reactive cathode material. A common trend with nitrogen and oxygen addition is the significant loss of the Ar and ArH ion signals. As the argon ion signal decreases, the molecular oxygen ion increases; however the molecular nitrogen ion does not exhibit the same trend. Our studies include monitoring ions produced in the glow discharge, comparing direct current and pulsed discharges, and evaluating sputter rates.

Critical revision of GD-MS, LA-ICP-MS and SIMS as inorganic mass spectrometric techniques for direct solid analysis

“…108 In addition, a common trend with nitrogen and oxygen addition is the significant loss of the Ar and ArH ion signals. 109 Thus, it should be stated that the presence of reactive gases has to be seriously taken into account in the quantification process (e.g. using different corrections for the light elements).…”

Ion Sources

“…Compared to established gaseous and solid state mass spectrometric techniques, the combination of an ICP ion source with a mass spectrometer is a relatively young analytical technique. [7][8][9] Especial attention was focused on the inherent drawback of ICP-MS, the occurrence of isobaric interferences in mass spectra (often named 'isobaric overlaps') of atomic ions of analytes by disturbing polyatomic ions (e.g, 56 Fe + and 40 Ar 16 O + ) or by isobaric singly charged (e.g., 40 Ca + and 40 Ar + or 92 Mo + and 92 Zr + ) and doubly charged atomic ions at the same nominal mass (e.g., 28 Si + and 56 Fe 2+ ), respectively. 5 Just nine years after the introduction of ICP-OES, the first commercial ICP-MS (Elan 250, Perkin Elmer Sciex) was produced for routine applications.…”

“…92 A glow discharge ion source combined with a mass spectrometer has supplanted the spark ion source over many decades as the predominant ionization technique of mass spectrometry for determining trace and ultratrace element concentrations in various types of solid samples. 92 A glow discharge ion source combined with a mass spectrometer has supplanted the spark ion source over many decades as the predominant ionization technique of mass spectrometry for determining trace and ultratrace element concentrations in various types of solid samples.…”

“…93 The main preference for GDMS over SSMS is that the atomization of solid material and ionization of neutrals are separated. 92 By applying a sufficiently high voltage (e.g., 1 kV) between the two electrodes, gas breakdown occurs and plasma of positively charged ions and electrons is formed. As a result, in GDMS compared to SSMS, a better precision of analytical data is obtained.…”

A purged argon pre-chamber for analytical glow discharge—time of flight mass spectrometry applications

“…As a result, the analytical performance of the technique has been improved, particularly enhanced sensitivity in the afterglow time domain (i.e. after the end of the pulse) 3,4 and temporal discrimination of the analyte from potential isobaric interferences have been also observed. 5,6 For most analytical use configurations, the sample seals the GD source at ambient pressure, so the analysis can be run just after the sample is placed in the system, saving time compared to other techniques such as secondary ion mass spectrometry (SIMS) where a pre-vacuum chamber is needed prior to sample introduction in the SIMS analysis chamber.…”