The only time that I use the offline correction in the JEOL software, and it is very rare that I do, is to restore net intensities back to their original values if a given standard has been recalibrated between the time a user acquired their original data and the time at which the wish to recalculate data, specifically when they wish to switch a given standard to recalculate their analyses. In that case, they need to be able to switch the standard intensities back to what they were when their data were first collected, in the event that the standard they wish to switch to for a given element has been recalibrated.
If I couldn't alter the standard intensities, then I'd have to recalibrate and hope that the recollected intensity was close to what it was at the time when the user actually collected the original data, which would basically be a luck-of-the-draw prospect.
Hi Dan,
Thanks for the info. I understand better now what you want to do and why.
First of all, the reason you give above concerning someone replacing a standard intensity in the shared table, can never occur in Probe for EPMA precisely because another user (or even oneself), *cannot* edit a standard intensity once it is acquired. This is because the standard intensities are in your own data file and therefore not generally accessible to other users, though of course they can be exported and "shared" with other runs/users.
The only other time I can think of needing to do this might be if I had to readjust a base-plate in the spectrometer to correct for a wonky take-off angle - in that case, recollecting the standard intensity data to use on an old data set isn't too likely to be the same as it was originally. This would be a rare case, indeed, but stranger things have happened with my probe.
Generally, if there is any doubt about the quality of the standard data or the unknown data, the very best way to proceed is to recollect the data. In the case where the user had provided their own certified standard, logistics may make recollection impossible.
Yes, I agree. The best recourse would be to simply re-acquire the standard and then you are back in business! Unless of course the user re-adjusted the spectrometer alignment!
Don't forget there is an automatic standard intensity drift correction built into Probe for EPMA so each time you re-standardize, it corrects for any changes in standard intensities, but it does assume that the intensity drift is linear, though of course in the case of a spectrometer re-alignment it won't be.
An analogous situation would be a spectrometer that has been re-peaked in the middle of a run. My advice: don't do a re-peak, instead just re-standardize and the intensity change (if any) will be handled automatically by PFE.
But if you must re-peak a spectrometer for some reason, do this: standardize, re-peak and then re-standardize! Then all is handled automatically.
Let me know if I'm not clear. It's a lot to think about.
john
Please keep your software updated for best results!