Glow Discharge Mass Spectrometry (GDMS)

Glow Discharge Mass Spectrometry (GDMS)

Glow Discharge Mass Spectrometry (GDMS) is a form of mass spectrometry in which, usually, Argon plasma is generated using a low current electrical discharge (milliamps) in a Glow Discharge Vacuum chamber filled with Argon gas. Positively charged Argon plasma ions accelerate towards the cathode, which in the case of GDMS, is formed using the test sample. The release of sample atoms at the cathode, due to bombardment by Argon plasma, is termed ‘sputtering’. The sputtered atoms of the sample are ionized in the plasma and extracted through the anode into the mass spectrometer for detection and spectrometric analysis. Individual compounds have their own unique mass spectrum. When the spectrometer is operated in high resolution mode, this provides a powerful technique for the analysis of all trace and ultra-trace elemental constituents of inorganic materials.  The Glow Discharge ion source can be operated in three different electrical modes, namely Direct Current (DC), Radio Frequency (RF) and pulsed Glow Discharge systems. The radio frequency mode is used for non-conductive samples. The pulsed mode produces higher energy plasma ions for sputtering and hence, more analytical sensitivity.

GDMS has found widespread applications in the analysis of trace-level elements and chemical species at surfaces and within conducting and nonconducting solids or dispersed liquids. It is also used in nuclear technology for characterization of nuclear fuels, and materials testing for elemental and isotopic composition.

Common Uses of Glow Discharge Mass Spectrometry (GDMS)

• Compositional profiling of metals, semiconductors and ceramics
• Characterization of nuclear fuels and materials
• Determination of radioactive contamination in environmental samples
• Analysis of thin films

Advantages of Glow Discharge Mass Spectrometry (GDMS)

• Direct solid sample analysis, negligible sample preparation time
• Full element coverage (except Hydrogen)
• Detection of trace level (ppb) of species
• Relatively free from Matrix effects

Limitations of Glow Discharge Mass Spectrometry (GDMS)

• Spectral interferences in the mass spectrum due to impurity gas ions and cluster ions
• Non-conductors need to be powdered and mixed with conductive binders, since direct RF-GDMS equipment are not readily available
• Sequential operation of mass analyzers limits depth profiling application when compared to optical emission spectroscopy (GD-OES)

 Industrial Applications of Glow Discharge Mass Spectrometry (GDMS)

• Metals and alloys
• Aerospace
• Semiconductors
• Ceramics
• Environmental analysis
• Nuclear materials
• Forensics