Glow Discharge Mass Spectrometry
The main focus of MSI is high resolution glow discharge mass spectrometry (GDMS): a mature, versatile technique for the direct determination of elemental content (matrix to sub-trace) in a variety of materials. Glow discharge occurs on a molecular level by applying a potential difference between the anode and the cathode (analyte). As atomisation and ionisation occur separately, minimal matrix effects are observed. This makes it possible to use a standard Relative Sensitivity Factors (RSF) data set for all analyses.
After atomisation and ionisation in the plasma, the ions (M+) diffuse outside the cell and are accelerated down the flight path, through the electrostatic analyser (ESA) and the magnetic analyser (the magnet) to increase ion separation before detection by either the electron multiplier or Faraday cup, depending on signal intensity.