In search of the ultimate experiment for quantitative depth profile analysis in glow discharge optical emission spectrometry. Part I: Calibration curves

Abstract

AbstractThis is the first part of our search for an experiment that will show definitively which is the best method for quantitative glow discharge optical emission spectrometry (GDOES). Three empirical methods for producing quantitative depth profiles from GDOES data are examined: the SIMR method, the IRSID method and the most recent BHP method. All three methods give worthwhile quantitative depth profiles of thin films and coated materials. The first two methods assume that pressure does not have a significant effect on emission yield, while the third method assumes that pressure is the only significant parameter affecting emission yield. The different approaches therefore imply very different physical processes inside the lamp and it is essential for further development of quantitative GDOES that the best approach be determined. Depth profiling in GDOES is, in principle, simply bulk analysis repeated over and over as a function of depth. The three methods are therefore tested here in their ability to do bulk calibration in a range of steels and zinc–aluminium alloy standards, all at constant current. All methods worked well for steel, while the best calibration curves in zinc–aluminium alloys were obtained with pressure‐corrected IRSID and SIMR methods or a voltage‐corrected BHP method. The results suggest that emission yields depend on both voltage and pressure (and presumably current, which was not tested here in Part I).