Secondary boundary fluorescence correction in Probe for EPMA

[Probeman]

In case anyone is interested, attached below are the 5, 8, 10, 15 and 20 um Excel sheets for the above inclined geometries.

If anyone wants the complete PENEPMA calculations for these runs just let me know and I can send a download link as it's 46 MB.

Here's an example comparing a vertical boundary (0mdegrees) with a 70 degree sloped (inclined) boundary for Fe Ka in SiO2 adjacent to FeS2 at 15 um from the boundary. The k-ratios are:

0 deg: 0.001343
+70 deg: 0.000513

(0.001343 - 0.000513) / 0.001343 = 61% drop in intensity

at 10 um boundary, k-ratios are:

0 deg: 0.001683
+70 deg: 0.000617

(0.001683 - 0.000513) / 0.001683 = 69% drop in intensity

[Ben Buse]

Hi John
Great your looking at this
Is it now possible to model sloped planar interfaces in FANAL?
The other issue is where the interface is small - inclusions. Below is simulations for cuboids of varying sizes, together with planar interface from DTSA-II, and comparison to FANAL

[Probeman]

Is it now possible to model sloped planar interfaces in FANAL?

Unfortunately, not that I know of.  The sloped interfaces were all generated in PENEPMA, which of course is very time consuming.  I really do not not how to proceed from here as characterizing the actual angle of slope is not possible in an EPMA I suspect.

I should do another system with say a less energetic x-ray and see if the geometry alone dominates or also the x-ray physics.

The other issue is where the interface is small - inclusions. Below is simulations for cuboids of varying sizes, together with planar interface from DTSA-II, and comparison to FANAL

It's nice to see that DTSA2 and PENFLUOR/FANAL agree on a vertical plane geometry.

[John Donovan]

Attached below is the poster from Aurelien Moy and I for M&M 2025 for those who are unable to attend.  For those who will be present at the meeting, the poster session is Thu morning (10-12).

Looking forward to answering any and all questions.

[Probeman]

I was recently looking over our secondary boundary fluorescence paper of Llovet et al. and I found this statement, which claims that the development of code for on-line EPMA analyses, of trace elements near boundaries of phases containing significant concentrations of the elements, should be "straightforward" and I had to smile.



Not because the code isn't straight forward as it's really not too bad, one just needs to iterate the adjusted k-ratios  during the matrix correction, but because of all the complications that can occur with actual samples, for example Ben's question below.  Not to mention the complication of correcting for WDS Bragg defocus when the distances are greater than 20 um or so. Fortunately as the distance increases the boundary fluorescence effects decrease!

https://smf.probesoftware.com/index.php?topic=1545.msg13214#msg13214

But I also noticed in the Llovet paper a reference from 1983 by Bastin, which I then had to look up and it is attached as a pdf to this post.  It really is worth a read, but one thing they mentioned several was the difficulty in dealing with non-vertical boundary geometries.

Is it now possible to model sloped planar interfaces in FANAL?

Yes, we can model sloped boundaries in PENEPMA, one damn distance from the boundary at a time, but it is time consuming and then one needs to format a k-ratio.dat input file in the FANAL format, but also as I mentioned previously, how do we know the actual geometry of the boundary?

https://smf.probesoftware.com/index.php?topic=1545.msg13373#msg13373

Right now I would suggest that perhaps another method, though it also is time consuming, is to use a FIB instrument to extract a small piece of the material near the boundary, mount it and then take it to the EPMA to get the trace elements.  Yeah, a pain but this is what a colleague of mine did for her Ti in quartz analysis in a sample with lots of rutile grains:

"A select few of the newly formed quartz and tridymite crystals from double capsule and single capsule experiments were painstakingly separated from nearby TiO2 and analysed using a novel combination of the plasma focused ion beam (PFIB) and EPMA (Appendix A.2 and A.3)."

https://www.sciencedirect.com/science/article/pii/S0016703720302891

[sem-geologist]

As you mentioned FIB. I have an another alternative idea: What about cutting the trace and filling it with something heavy which would significantly absorb X-rays going over boundary? i.e. Ag, Pt or something else - it would be much much less work and more straight forward.

As for non perpendicular boundary.. maybe rastering across boundary and using kind of modified composite layer techniques would allow to reconstruct exact angle? Another idea is to go back to optical methods – I think even using optical microscope with motorized Z - reconstruction in 3D of boundary and getting precise angle is quite trivial. for more complicated cases Raman 3D tomography also could be useful. Would knowing exact geometry help in the modeling the secondary fluorescence effect more easier?

[Probeman]

As you mentioned FIB. I have an another alternative idea: What about cutting the trace and filling it with something heavy which would significantly absorb X-rays going over boundary? i.e. Ag, Pt or something else - it would be much much less work and more straight forward.

Maybe.  But the problem is not just characteristic fluorescence, but also continuum fluorescence, which can be much higher energies and hence more penetrating.

Would knowing exact geometry help in the modeling the secondary fluorescence effect more easier?

Knowing the "exact geometry" might not be necessary, but just knowing the approximate boundary slope would be helpful as it's a "wicked" effect:

https://smf.probesoftware.com/index.php?topic=1545.msg13373#msg13373

As I said, getting the slope of the boundary interface might not be easy, but it would improve accuracy.

[sem-geologist]

Attached below is the poster from Aurelien Moy and I for M&M 2025 for those who are unable to attend.  For those who will be present at the meeting, the poster session is Thu morning (10-12).

Looking forward to answering any and all questions.

BTW, this poster is Gold! Everytime someone wants to "measure" "diffusion" across boundary with EPMA I just redirect them to that poster. Papers are nice - but to grasp the severeness of effect people need to read them. Poster have much faster direct impact in such cases.

[John Donovan]

Attached below is the poster from Aurelien Moy and I for M&M 2025 for those who are unable to attend.  For those who will be present at the meeting, the poster session is Thu morning (10-12).

Looking forward to answering any and all questions.

BTW, this poster is Gold! Every time someone wants to "measure" "diffusion" across boundary with EPMA I just redirect them to that poster. Papers are nice - but to grasp the severeness of effect people need to read them. Poster have much faster direct impact in such cases.

Thank you SG!

For others who have not yet stumbled across this poster it is attached to the reply linked here:

https://smf.probesoftware.com/index.php?topic=1545.msg13549#msg13549

And remember, to see attachments, you must be logged in as a member.