Hi all
Ressurecting an old post...
I have finally had some time to get around to looking at some of my spectrometer intensities over time on various standards/xtals using the Drift program. I am after an opinion on some of the trends I am seeing, and whether or not they are indicative of the need for some xtal alignments, or if there is some other effect/problem.
Looking at the first attachment, it is my Ti Ka intensity on LPET(sp3) on one of the rutile standards collected over the course of ~3 years. Over that period the intensity (blue line) has dropped, perhaps more drastically in a couple of bigger steps, but no denying is lower now than what it was three years ago. The offset of peak from theoretical (orange line) was never bang on, but you could argue is also definitely further away from theoretical than a few years ago.
The second attachment is my Si Ka intensity on TAP(sp4). In this plot it is more a steady decline in peak intensity over a few years. The peak offset from theoretical, although noisy, is hovering around zero, but this is a function of Si being the element Cameca users "verify" on for their TAP xtals, forcing it to its correct sintheta value.
I know there are probably many variables (how well I peaked, standard degradation? etc), but on the whole perhaps they are in need of some alignment? How often are people getting their xtals aligned?
While on this, perhaps I am understanding the Cameca verification routine wrong, and/or not completely understanding what it does. Take the LLIF xtal where we verify on Fe Ka forcing it to the theoretical position, then applying a linear offset/correction to the entire spectrometer. Given that verification is done often, shouldn't this be correcting for the "Peak offset" seen in the Ti Ka plot I have attached? Or is this the kind of error involved in that offset/correction and its not linear?
Not sure if any of that made sense..
Cheers