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Published on: July 11, 2017
Glow discharge source interfacing to mass analyzers: theoretical and practical considerations.
1Nuclear Materials and Technology Division, NMT-1, Los Alamos National Laboratory, MS G740, Los Alamos, New Mexico 87545, Life Sciences Division, LS-5, Los Alamos National Laboratory, MS M888, Los Alamos, New Mexico 87545, Chemical Science and Technology Division, CST-9, Los Alamos National Laboratory, MS K484, Los Alamos, New Mexico 87545, and Department of Chemistry, University of Florida, Gainesville, Florida 32611.
Analytical Chemistry
|June 14, 2011
Summary
Glow discharge ion sources offer distinct advantages over inductively coupled plasma sources for mass spectrometry. Key differences in ion sampling and extraction processes were identified, optimizing instrument performance.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Atomic Spectroscopy
Background:
- The interface between ion sources and mass spectrometers is critical for optimal analytical performance.
- Glow discharge (GD) and inductively coupled plasma (ICP) are common ion sources, each with unique characteristics.
- Understanding these differences is essential for efficient ion sampling and extraction.
Purpose of the Study:
- To describe the fundamental requirements for an optimal mechanical interface between a glow discharge ion source and a mass spectrometer.
- To compare and contrast GD and ICP ion source interfaces.
- To present experimental results clarifying glow discharge ion sampling and extraction processes.
Main Methods:
- Theoretical review of critical parameters and considerations for GD and ICP ion source interfaces.
- Experimental investigation using quadrupole and time-of-flight mass spectrometers coupled with a GD source.
- Analysis of ion sampling and extraction phenomena in GD ion sources.
Main Results:
- No shock wave structure observed in the supersonic expansion of the GD ion source.
- Ions of different masses exhibit similar initial kinetic energies, making skimmer cone angle non-critical for extraction.
- Space charge effects in GD sources cause preferential off-axis repulsion of heavier ions compared to lighter ions.
Conclusions:
- Fundamental differences exist between GD and ICP ion sources regarding ion sampling and extraction.
- GD ion sources do not exhibit shock wave phenomena, simplifying interface design.
- Understanding space charge effects is crucial for optimizing ion beam extraction in GD-MS systems.
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