Ion Kinetic Energy Determinations in Radio-Frequency Glow Discharge Mass Spectrometry

Paula R. Cable, R. Kenneth Marcus

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Radio-frequency glow discharge (rf-GD) sources produce an abundance of both atoms and ions. For the mass spectrometric application of the glow discharge technique, knowledge of the ion kinetic energies is required to optimize extraction and focusing of ions from the source region into the analyzer. This paper details kinetic energies experimentally determined with the use of the “retarding potential” method. For this study, the analyzer quadrupole of a double-quadrupole mass spectrometer was positively biased to act as a repeller. Ion kinetic energies (IKEs) determined for a variety of discharge and analyzer operating conditions ranged from 12.5 eV to 25.0 eV for 63Cu+. Kinetic energy measurements were confirmed from ion trajectory simulations and follow closely the experimental values for identical analyzer conditions and initial IKEs. Results of this study indicate that the conditions under which ions are formed (plasma conditions) affect IKEs and energy spreads to a greater extent than analyzer parameter variations. Different from atmospheric plasma sources, IKEs for rf-GD species do not vary as a function of ion mass/identity. Evidence is also given in support of a slight mass biasing owing to the transmission properties of double-quadrupole analyzers. The findings detailed herein demonstrate the effects of rf modulation on both ion kinetic energy values and distributions.

Original languageEnglish
Pages (from-to)917-926
Number of pages10
JournalApplied Spectroscopy
Volume49
Issue number7
DOIs
StatePublished - Jul 1995
Externally publishedYes

Keywords

  • Ion kinetic energy
  • Mass spectrometry
  • Quadrupole mass filter
  • Radio-frequency glow discharge

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