Recent improvements in GDOES

Technical modification of the Grimm lamp (a hollow-cathode lamp operating in the microwave-boosted mode) has given increased sensitivity compared to the conventional hollow-cathode lamp [1041. Argon line interferences have been removed by introducing a third electrode to modulate the intensities (lO. )). A low-pressure device can be introduced in order to decrease atmospheric contamination of the sample [106]. Fa.st Fourier transform analysis of emitted light has provided increased sensitivity (e.g.. Mo in steel down to 50 ppm [I07 ). 

In special cases GDOES can operate at much lower erosion rates and then becomes a surface depth profiling technique with the same depth sensitivity as. for instance, AES (108j. However, the effectiveness of GDOES lies in its high-sputter-rate mode. Other emission spectroscopies from surfaces are available, such as spark or la.ser ablation spectro.scopies, but they are less well adapted to quantitative depth protlling than GDOES. 

A vacuum chamber is not required (except to detect O, N and H lines in extreme UV). 

The depth resolution is poor (in comparison with AES, XPS or SIMS). 

It is not normally a surface analysis technique (i.e., not in the nm range). The lateral re.solution is poor. 

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