CORRECTING FOR BACKGROUND AND INTER-ELEMENT EFFECTS IN GLOW-DISCHARGE OPTICAL-EMISSION SPECTROMETRY

The background signal in glow discharge optical emission spectrometry (GD-OES) is shown to comprise at least four components: a constant term, an argon term, a matrix continuum term and a matrix line term. The constant term includes photomultiplier dark current and other noise sources, the argon term is emission from excited argon atoms in the plasma, the matrix continuum is from continuum emission from the sputtered material, and the matrix line term is from line interferences, so called inter-element effects. Iron is shown to be a major source of continuum background. A simplified equation is provided for the GD-OES background which is shown to increase the dynamic range in depth-profiles and reduce depth-profiling artefacts by correcting for changes in the background signal with changes in the matrix during sputtering and by reducing inter-element effects.