Indeed, I discovered that in this case the variation in Si ka Net Intensity was due to the misidentification of Ta M-lines. After applying a mask for all but the elements that were present, the Net Intensity returned for Si for the two spectra mentioned in the original post were more reasonable:
Line = 258
EDS Spectrum Net Intensities:
mg ka, net intensity=10858.76, net background= 0, net (cps) error= , net error= 37.12778
si ka, net intensity=7633.333, net background= 0, net (cps) error= , net error= 25.07222
fe ka, net intensity=1213.2, net background= 0, net (cps) error= , net error= 5.661111
Line= 260
EDS Spectrum Written to OEM System...
EDS Spectrum Net Intensities:
mg ka, net intensity=10861.81, net background= 0, net (cps) error= , net error= 37.13889
si ka, net intensity=7642.511, net background= 0, net (cps) error= , net error= 25.1
fe ka, net intensity=1216.611, net background= 0, net (cps) error= , net error= 5.666667
That's 5623cps with Ta, 7633cps without. I am a little surprised by the magnitude of the error created by an apparent 0.5wt% Ta?
Anyway, I wonder if it is possible that I am seeing misidentified peaks because I do not have my Thermo system 'optimised' in some way?
However, if misID of peaks is a problem, then it raises some interesting questions about reprocessing data at a later date. Since there is currently no scope for a 'mask' to be sent from PFE vis the NSSPortal, I will be suggesting to my users that they create a new NSS project called PFExyz (with appropriate mask) for every PFExyz.mdb they create, and to make sure that this NSS project is current in NSS before reprocessing occurs. Another option here would be to save a template.TNP file (with an appropriate name) that could be used to quickly recreate the mask as needed.
John, I wonder (in a world of endless time and resources) whether the:
TEVB ProjectExplorerDisplay
function could be sent the first time EDS data is calculated in a .mdb, to force the user to make a selection of an appropriate project??
From TEPortal doc:
TEVB ProjectExplorerDisplay
This function is used to instruct NSS to display its project explorer dialog. This function will block until the dialog has been closed.
Gareth