Secondary boundary fluorescence correction in Probe for EPMA

[Probeman]

Perhaps some of you have noticed this button the the Probe for EPMA Analyze! window:



This button (and the associated GUI and code) is intended to apply quantitative boundary fluorescence corrections for intensity data contained in Probe for EPMA database files, with a graphical user interface similar to (but somewhat different than) what we have already have in our CalcZAF application:

https://smf.probesoftware.com/index.php?topic=58.msg12980#msg12980

That is, one could simply subtract the calculated concentrations from secondary boundary fluorescence from one's quantitative results after the fact, e.g., in Excel, but it is more rigorous to subtract the actual boundary fluorescence intensities during the matrix correction, so that the new matrix is recalculated correctly (similar to the quantitative interference correction) since the matrix composition is changed by the correction. Yes, in many cases the correction is so small that it won't matter, but is some cases of boundary fluorescence the apparent (artifact) concentration of an element can be several percent or more, and therefore should be included in the matrix correction.

The reason for explaining all this is to say that I believe we are ready to start testing this new feature in Probe for EPMA, but we would like to have a suitable sample with a large boundary fluorescence correction for testing purposes. One such ideal sample would be a sample with a pure Fe and pure Ni vertical interface that has *not* been polished together, in order to avoid smearing of one element to another.

I have pure Fe and pure Ni materials (though other pure element pairs such as pure Cu and pure Co would be even better from a boundary fluorescence artifact perspective) and I would be happy to send those to someone who would be willing to produce a sample with suitable geometry for testing this new code.  If any one is willing to produce such a sample we would be happy to include them as a co-author.

Please let me know if you would be willing to help with this project.

[John Donovan]

We've been waiting for some test data for this new secondary fluorescence boundary correction, but this weekend I was going through some old samples and found a synthetic boundary sample consisting of a pure Fe metal next to a pure Ni metal which had been polished individually to yield a vertical boundary. Polishing the materials separately is necessary to avoid any "smearing" from one material to the other.

The idea being to measure trace Fe in a Ni material that is adjacent to a Fe material. The physics here is that any Ni Ka generated in the Ni material can easily travel a significant distance through the Ni and fluorescence the Fe K edge in the Fe material.  In addition any continuum created in the Ni material that is over the Fe K edge energy (7.1 keV) can also fluorescence Fe.

So the first step in this correction is to model the situation using the PENFLUOR/FANAL GUI in the Standard application as described in this topic:

https://smf.probesoftware.com/index.php?topic=58.0

Performing the steps described in the above topic yields the following plot:



Note that the beam incident material is pure Ni, the boundary material pure Fe and the standard material is pure Fe metal.  Your analytical situation will undoubtedly be different, but the steps are essentially the same for any emission line and materials.

When the plot is generated by Standard, it will create a folder containing the results using the naming convention: <takeoff>_<keV>_<beam incident>_<boundary>_<std>_<element atomic#>_<xray#> where <xray#> is the x-ray line number, ka=1, kb=2, la=3, lb=4, ma=5, mb=6.

Therefore, for the measurement of Fe Ka in Ni metal, adjacent to Fe metal, using an Fe standard at 15 keV measured at a takeoff angle at 40 degrees the necessary files for performing this correction are saved automatically in a sub folder in the C:\UserData\Penepma12\Fanal\Couple folder as seen here:



If secondary fluorescence from the boundary material is indicated, you will now be able to perform the correction in Probe for EPMA. After opening this folder you will see these files:



The k-ratios.dat file is the one you will be browsing for in a moment from Probe for EPMA.  The Fanal.txt file will also be utilized but is loaded automatically.

But before we go any further I just want to mention that this synthetic boundary sample is not ideal as there is a roughly 30 um gap between the Ni and Fe materials which means that the physics we just modeled above is not exactly correct, but I hope it will suffice as a demonstration example until you all can provide some real world examples of boundary fluorescence!

So we started the analysis points right at the edge of the Ni material and then went in 1 um steps inward. Now let's open our probe run database in Probe for EPMA and go to the Analyze! window as seen here and click the analyze button as usual and see our results :



Not that at the edge of the Ni material (and ~30 um) from the Fe material, we obtain almost 0.5 wt% of Fe in the pure Ni which is from these secondary boundary fluorescence effects.

[John Donovan]

Continuing from the post above...

Now let's correct for these SF effects.  Start by selecting the sample(s) in the Analyze! window sample list and then click the Boundary Corrections button in the Analyze! window. The Secondary Fluorescence Correction from Boundary Phase dialog will open as seen here:



Note that the above steps can be performed in any order but all need to be completed before the SF corrections can be performed. In the above example, we simply selected an image from our saved images, then we clicked the Define Boundary Method button to define the boundary to open the Secondary Fluorescence Boundary Correction Parameters dialog as seen here:



In the above example, we clicked the Specify Graphical Boundary option and then using the mouse, we drew a boundary on the image as shown (one can also specify the boundary geometry using stage positions if an image is not available). The boundary was drawn partially in the gap between the phases because the physics we modeled is not exactly correct because we assume no gap in PENFLUOR/FANAL physics calculations.  Note that normally you will not have a gap between your phases so this issue can be ignored for now, but there are ways of dealing with a gap between phases that can be discussed later.

Note also that we oriented this synthetic boundary in the instrument so that the boundary was pointing directly at the WDS spectrometer (Fe ka) making the trace measurement. For EDS spectrometers, this is not necessary, but until we implement a Bragg defocus geometry correction in Probe for EPMA (see https://academic.oup.com/mam/article-abstract/24/6/604/6901481 by Ben Buse et al. 2018) it is best to avoid Bragg defocus effects by orienting the sample relative to the spectrometer.  However, for boundary distances less than 10 or 15 um these Bragg defocus effects will be minimal.  If two trace elements need to be measured/corrected together, then spectrometers that are diametrically opposed to each other should be selected with the phase boundary pointing at both spectrometers.

Ok, let's proceed by now browsing for our modeled boundary fluorescence k-ratios.dat file as seen here:



If the correct file was selected, the k-ratios as a function of boundary distance will be loaded as shown previously above.  Note that on the right side we can see the Mat A, Mat B and Mat B std materials utilized in the PENFLUOR/FANAL calculations. Now we just click OK and click the Analyze button again:



Wasn't that easy!   

Ok, well it's better than doing it manually by hand...

To provide some additional details, these calculated k-ratios are subtracted from the measured k-ratios during the matrix correction procedures, so even if significant SF boundary corrections are performed, the calculation of the other elements in the modified matrix will be properly accounted for (in this regard this is similar to the quantitative spectral interference correction in PFE)

Though it should be mentioned that if the change in composition from the SF boundary correction is not large one can simply subtract the calculated concentrations in Excel or otherwise.  But the advantage of doing it in PFE is that the process is completely documented and fully quantitative.

Now one last note: the SF boundary calculation in PENFLUOR/FANAL assumes a vertical infinite boundary interface, which is not always the case of course with our samples.  We are also investigating the possibility of performing a geometrical correction to deal with hemispherical geometries for example, but in the meantime one can perform these boundary calculations the PENEPMA code using the Standard application as described here:

https://smf.probesoftware.com/index.php?topic=59.0

One would need to model each distance from the boundary so that will take a while, but one can use the Batch Mode button in the PENEPMA GUI to make it easy:

https://smf.probesoftware.com/index.php?topic=151.0

Then one would need to extract the k-ratios from each distance and create your own k-ratios.dat file similar to what is produced by PENFLUOR/FANAL (and the Fanal.txt file as well) and place it in an appropriately named folder.

Anyway, this is a new feature, so we'll be interested to hear from you all on using it for your own specific examples.

[John Donovan]

We've modified the secondary boundary fluorescence correction output in the latest Probe for EPMA to include the correction of the k-ratios and distances from the boundary to help troubleshoot any issues that arise:

SecondaryCorrection: SF k-ratios * 100, Line: 218, Dist: 14.25352
Element:   fe ka
Elm. Kr: .600537
Cal. Kr: .644139
Cor. Kr: -.04360

SecondaryCorrection: SF k-ratios * 100, Line: 218, Dist: 14.25352
Element:   fe ka
Elm. Kr: .600537
Cal. Kr: .644139
Cor. Kr: -.04360

SecondaryCorrection: SF k-ratios * 100, Line: 219, Dist: 15.25291
Element:   fe ka
Elm. Kr: .574921
Cal. Kr: .582388
Cor. Kr: -.00747

SecondaryCorrection: SF k-ratios * 100, Line: 219, Dist: 15.25291
Element:   fe ka
Elm. Kr: .574921
Cal. Kr: .582388
Cor. Kr: -.00747


Un    3 Fe in Ni SF boundary

Un    3 Fe in Ni SF boundary
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 30.0  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    633)
Image Shift (X,Y):                                         .00,    .00
Number of Data Lines: 101             Number of 'Good' Data Lines:   2
First/Last Date-Time: 09/10/2023 03:02:39 PM to 09/10/2023 06:30:15 PM

Average Total Oxygen:         .000     Average Total Weight%:   99.968
Average Calculated Oxygen:    .000     Average Atomic Number:   28.000
Average Excess Oxygen:        .000     Average Atomic Weight:   58.711
Average ZAF Iteration:        2.00     Average Quant Iterate:     2.00

No Sample Coating and/or No Sample Coating Correction

Un    3 Fe in Ni SF boundary, Results in Elemental Weight Percents

ELEM:       Fe      Ni
TYPE:     ANAL    ANAL
BGDS:      LIN     LIN
TIME:    60.00   60.00
BEAM:    29.87   29.87

ELEM:       Fe      Ni   SUM 
   218   -.031  99.997  99.966
   219   -.005  99.977  99.971

AVER:    -.018  99.987  99.968
SDEV:     .018    .014    .004
SERR:     .013    .010
%RSD:  -100.07     .01
STDS:      526     528

STKF:   1.0000  1.0000
STCT:   207.81  707.67

UNKF:   -.0003   .9999
UNCT:     1.25  726.33
UNBG:      .56    3.51

ZCOR:    .7202  1.0000
KRAW:    .0060  1.0264
PKBG:     3.24  208.14

The line numbers are duplicated because of the matrix correction iteration loop...

[John Donovan]

After responding to Alejandro's question here:

https://smf.probesoftware.com/index.php?topic=1620.msg12851#msg12851

I thought it might be worth expanding on the issue of Bragg defocus and the correction of secondary fluorescence from nearby grain boundaries for certain trace element situations...  because it is a bit related to the issue of *x-ray* interaction volumes (as opposed to electron interaction volumes).

For example, for EDS detectors, there is essentially no defocussing effect and therefore secondary fluorescence from grain boundaries (the x-ray interaction volume), will be present at levels as predicted by modeling softwares such as PENEPMA/PENFLUOR:

https://smf.probesoftware.com/index.php?topic=58.msg12652#msg12652

But because of Bragg defocus we need to consider the orientation effect of Bragg defocusing on the detection of emissions from grain boundaries when using WDS spectrometers.  That is, the magnitude of secondary fluorescence will depend on the relative orientation of the grain boundary to the Bragg crystal in a specific WDS spectrometer.

This orientation effect suggests two different approaches to dealing with boundary fluorescence. One approach is to perform analyses near grain boundaries (when secondary boundary fluorescence is present) where the grain boundary is *perpendicular* to the Bragg crystal orientation (the long axis of the crystal) in a specific spectrometer:

https://smf.probesoftware.com/index.php?topic=58.msg5710#msg5710

This boundary to Bragg crystal orientation ensures that the intensities from nearby grain boundaries are suppressed as much as possible by the WDS defocusing. In fact, using this *perpendicular* orientation, as long as one chooses spectrometers that are 180 degrees from each other (as mounted on the instrument) the secondary fluorescence intensities from the grain boundary will be defocussed similarly, and one can even measure the trace element on *two* WDS spectrometers using the aggregate feature in Probe for EPMA:

https://smf.probesoftware.com/index.php?topic=1316.0

Therefore if the boundary fluorescence effect is small and the Bragg defocus is large, one *might* be able to avoid applying the boundary fluorescence correction in Probe for EPMA.

However, note that boundary fluorescence correction in Probe for EPMA:

https://smf.probesoftware.com/index.php?topic=1545.msg12034#msg12034

does not have a WDS Bragg defocus correction for boundary secondary fluorescence (maybe this post will get us starting work on that!).  See Buse et al., 2018:

https://academic.oup.com/mam/article-abstract/24/6/604/6901481

Therefore if one attempts to correct for secondary fluorescence from nearby grain boundaries using this *perpendicular* orientation approach, one will tend to over correct the boundary fluorescence intensities using k-ratios generated by PENEPMA/PENFLUOR.  This could result in slightly negative concentrations being reported for trace elements after they are corrected for boundary fluorescence.

In the meantime it is worth considering another approach. An approach where we orient the sample (or choose a grain boundary) so that the grain boundary is *parallel* to the Bragg crystal (long axis) orientation in the spectrometer! A *parallel* orientation ensues that little to no Bragg defocusing occurs to the intensities generated from our (nearby) grain boundary.

Why should we do this? Because then we minimize the WDS Bragg defocus effects and therefore the secondary boundary fluorescence correction will be more accurate using k-ratios generated from our PENEPMA/PENFLUOR modeling. 

However, note that other geometric effects also need to be considered. For example the PENFLUOR/FANAL calculation assumes an infinite vertical grain boundary whereas our actual sample might not be.  Though it is worth noting that if one is willing to make the effort, one can model a specific grain boundary geometry in PENEPMA, along with a specific WDS spectrometer orientation (though I do not know of a way to specify a Bragg defocus effect in PENEPMA), to get a more accurate prediction of the boundary fluorescence effects.  But this will require significant modeling time as each beam position (distance from the grain boundary) will need to be modeled one at a time.

In summary, ensuring a grain boundary orientation *parallel* to the spectrometeer Bragg crystal in order to minimize WDS defocusing effects allows one to utilize PENFLUOR to generate the boundary fluorescence k-ratios.  And PENFLUOR is so much easier and faster to use!

[John Donovan]

I drew up this quick schematic to better illustrate the points made in the previous post of Bragg defocusing and secondary boundary fluorescence:

[Probeman]

In addition to the discussions above regarding WDS Bragg defocus and the dependence of secondary boundary fluorescence intensity on the orientation of the grain boundary relative to the WDS spectrometer orientation, there's an important point that needs to be made regarding the placement of analysis points near a boundary...

When selecting analysis points, one should be sure to only place the analysis points on one side of the boundary or the other (per sample). This is applies whether one is applying the secondary boundary fluorescence correction off-line (by using the k-ratios.dat output from the PENFLUOR/FANAL or PENEPMA calculations) in Excel or CalcZAF (for better accuracy), or applying the SF correction within Probe for EPMA as discussed in this topic (for best accuracy).

That is, one must keep in mind that the appropriate correction applied depends on which material is the "beam incident material", and which material is the "boundary material".

The material containing the analysis points are of course always defined as being the beam incident material and that is how the calculation in Standard should be set up:

https://smf.probesoftware.com/index.php?topic=58.0

Here's a schematic to illustrate:



This distinction between the beam incident and boundary materials is critical for obtaining an accurate secondary fluorescence boundary correction. For example, here we have a screen shot of the PENFLUOR/FANAL window in the Standard application where the beam incident material is pure Ni and the boundary material is an alloy of Ni (99%) and Fe (1%):



It appears that we have ~1000 PPM of Fe in our pure Ni, but in fact this is a secondary fluorescence artifact (this SF artifact will grow as the concentration of Ni in the boundary material is larger). This artifact is because the Ni Ka (and continuum) x-rays in the pure Ni fluoresce the Fe in the Ni-Fe alloy as the analysis spot approaches the alloy boundary.

If we switch the beam incident and boundary materials, we get a completely different plot:



Here it appears that our Fe concentration in our Ni-Fe alloy decreases by ~1500 PPM as the pure Ni boundary is approached.  Again, this is 100% a secondary fluorescence artifact! It occurs because the Fe in the Ni-Fe alloy is being self fluoresced by the Ni x-rays produced in the alloy, but as the analysis points approach the boundary, there is no Fe in the pure Ni boundary material to fluoresce!

So, if you suspect that you may have a secondary fluorescence (positive or negative) from a nearby phase boundary, you should first check using the PENFLUOR/FANAL GUI in the Standard application to see how significant it is. Then place your analysis points in the beam incident material according to the SF boundary model you ran.

Of course, if you want to measure your elemental concentrations on both sides of the phase boundary, that is fine, but just be sure to make different samples, each with your analysis points only on one side of the boundary and be sure to apply the appropriate SF boundary model to each sample!

[John Donovan]

As pointed out here:

https://smf.probesoftware.com/index.php?topic=58.msg12980#msg12980

we've modified the secondary fluorescence code to handle boundary fluorescence corrections for more than one element at a time, also in Probe for EPMA.

Probeman is trying to get some test measurements for us, but the UofO EPMA is having some troubles (it's getting old just like me!).

So if any one would be willing to acquire some boundary fluorescence data for us, we would really appreciate it.  One easy test sample comes to mind. And that would be a low temperature quartz sample where the quartz grain (ideally ~1 mm in size and a mostly vertical boundary) is adjacent to an ilmenite grain, since both Fe and Ti (and Mn?) will be excited by the quartz continuum:

So if you have an EPMA instrument with 2 or 3 LiF spectrometers and can measure these elements plus Si, that would be great.

As mentioned in the above posts you'll want to point the grain boundary towards one of the LiF spectrometers and acquire points perpendicular to the boundary to minimize Bragg defocusing. Ideally we'd want to know the ilmenite composition in order to model it and perhaps a check on the Fe, Ti and Mn concentrations in the quartz to make sure they are close to zero...

Be sure to update to the latest PFE version to make sure the proper arrays will be present as we might even want to try a Bragg defocus correction later on.

Does anyone have a suitable sample like this that they would like to perform some measurements on so we can test this new code? Hey, you can be first author on any publications...

[John Donovan]

We've recently added a Bragg defocus correction to the secondary boundary fluorescence correction in v. 14.0.2 of Probe for EPMA.

This correction is first of several additional corrections needed to improve the accuracy of the boundary fluorescence correction on actual measurements. That is when measuring an element in a material adjacent to a material containing that element:

https://smf.probesoftware.com/index.php?topic=58.0

For example, measuring Ti Ka in quartz, adjacent to rutile.  Or Ca Ka in olivine adjacent to anorthite..., etc.  That is, don't attempt to derive your thermodynamics from a fluorescence artifact!

The additional corrections mentioned above are necessary, because the degree of secondary fluorescence from a boundary phases depends on several factors in addition to the distance to the boundary. For example:

1. Is the actual phase boundary geometrically similar to the boundary geometry that was utilized in the Monte Carlo modeling?  For example, the PENFLUOR/FANAL modeling is very easy and convenient to use, but it assumes a vertical boundary that is infinitely wide.

2. The PENFLUOR/FANAL modeling also assumes that the boundary is infinitely thick, which may not a good assumption when the sample is a 30 um thick thin section.  In case one is wondering, almost 60% of Fe Ka x-rays are transmitted in SiO2 at a thickness of 30 um:



3. In addition, and the point of this post, in WDS, depending on the orientation of the boundary relative to the spectrometer orientation, one may require a Bragg defocus correction for points further from the boundary. Although, if the boundary fluorescence is very small to begin with, this defocus correction may not be significant.

Ideally we would make our measurements along a line perpendicular to the boundary orientation. In this way, no Bragg defocus will occur, for many millimeters away from the boundary.  This is discussed here:

https://smf.probesoftware.com/index.php?topic=1545.msg12858#msg12858

But if we can't rotate our sample to this orientation relative to the spectrometer making the measurement, we will have to correct the boundary correction k-ratios for this effect in software.

This correction will be applied in the boundary corrections dialog which is accessed from Boundary Corrections button in the the Analyze! window as seen here:



The boundary correction dialog and the new Bragg Defocus correction button is seen here:



To be continued...

[John Donovan]

Continuing from the previous post on the correction of Bragg defocus effects on secondary boundary fluorescence calculations from nearby boundaries, let's start with this image from Glenn Poirier of a pure Fe standard using a low magnification beam scan on his spectrometer 4 LiF crystal:



The arrows on the above image indicate the direction of maximum Bragg defocusing for that spectrometer. That is, if your nearby phase boundary is in either of these directions, you will almost certainly overestimate the secondary boundary fluorescence correction calculated by PENFLUOR/FANAL:

https://smf.probesoftware.com/index.php?topic=58.msg214#msg214

So we have now added a new button here in the Boundary Corrections dialog (accessed from the Analyze! window in Probe for EPMA) as seen here:



The new dialog is seen here:



Basically, one must first acquire and then import a PrbImg x-ray map from Probe Image for the element, x-ray, spectrometer and crystal using a low magnification beam scan on a homogeneous material containing a major concentration of the element of interest, by using the Browse for a Low Magnification X-Ray Beam PrbImg File button...

That is, a low enough magnification that includes an area equivalent to the area of the point analysis and the phase boundary, where for the purposes of the defocus correction, each analysis point is assumed to be centered in the Bragg defocus x-ray map to calculate the distance and direction of the phase boundary.

Next, one can assign this defocus image to the selected element (which must already be specified for a boundary fluorescence correction), and update the assignment using the Update... button (be sure to check the box!).

The Bragg defocus correction has essentially no effect when the analysis point is close to the boundary, but becomes a larger correction the further away the analysis point is from the boundary (assuming the phase boundary is not parallel to the spectrometer orientation!), as seen here:



Here we see a measurement of Fe in quartz adjacent to pyrite. Without a secondary fluorescence correction we get a completely spurious result. With the SF boundary correction we get a better result but slightly over corrected. By including a Bragg defocus correction we see the accuracy improves especially for points further away from the boundary.

In summary the Bragg defocus correction can be helpful to avoid over correction of secondary boundary fluorescence effects when the analysis points are some distance from the boundary.

Actually, during the course of this work we discovered that there is a larger over correction effect that appears to be due to non vertical boundary geometries. This over correction mostly affects analyses close to the boundary. We are working with Xavier Llovet on this now and will report back with more results in a few weeks.

In the meantime you can update your Probe for EPMA using the Help menu as usual, or if your software is more than a few months old, please use the link near the bottom of our Resources page here:

https://www.probesoftware.com/resources/

This download link will enable to you to update Probe for EPMA and once again be able to use the Help | Update Probe for EPMA menu for subsequent updates.

[John Donovan]

Here's the same points plotted as above but for spectrometer 4 (LiFL):

[John Donovan]

Working with Aurelien Moy and Tanner Helland we implemented a smoothing algorithm for the Bragg defocusing correction on the low mag beam scan map intensities.  Here's the original data:



and here again with the smoothing method:



The method we utilized rotates the x-ray map based on the spectrometer orientation, and then applies a horizontal smoothing, then un-rotates the images before the Bragg defocus correction is applied.  One can toggle the smoothing correction in the GUI, but the smoothing method is always applied in the quantitative correction automatically.

That said, this smoothing is a correction, on a correction (Bragg defocus), on another correction (secondary boundary fluorescence).  So not a big effect overall, but it does improve accuracy when your low mag Bragg defocus calibration map sample is not uniform due to sample defects, and was fun to implement!   

On another note, the more serious accuracy issue for the secondary boundary fluorescence correction that we are currently working on is how to deal with non-vertical boundary geometries.  Yes, one could model a non-vertical boundary in PENEPMA for each distance from the phase boundary, but that would be quite time consuming!

We're currently modeling some non-vertical boundary geometries in PENEPMA (thanks to Xavier Llovet for the .geo files), and hope to find a method to apply this to real samples. Here's the issue:



That is, when the phase boundary slopes away from the analysis point, the contribution from secondary boundary fluorescence is less than predicted by the PENFLUOR/FANAL mode, and of course if the boundary slopes towards the analysis point it would underestimate the boundary effect.

Anyway, just something we're working on...

[John Donovan]

Some recent improvements to the secondary boundary fluorescence correction in Probe for EPMA.  Please note that this correction is built into the quantitative matrix correction since the k-ratios are adjusted during the correction, so an iterative correction approach is required for best results.

But first just a reminder that the k-ratios used for this correction can be easily loaded from your PENFLUOR/FANAL modeling for multiple elements on multiple spectrometers by browsing to the appropriate k-ratios.dat file based on the beam incident material, boundary material and primary standard utilized in your Probe for EPMA analyses:



See here for step by step directions for creating these k-ratios.dat files:

https://smf.probesoftware.com/index.php?topic=58.msg214#msg214

Second, one can now select whether to display disabled points (and/or duplicate points) in the graphical overlay when using a graphically defined boundary image.

This is a synthetic Fe-Ni boundary which I had made from pure Fe and pure Ni separately polished by Julie Chouinard. Unfortunately it is very difficult to get the boundary to meet exactly together at the surface, so we were left with a ~30 um wide gap.  So where to place the boundary. I choose to put it roughly in the middle of the gap!

Here is the quantitative results for Fe Ka measured in the Ni metal with and without the secondary boundary fluorescence correction:

[John Donovan]

Note also that the latest Probe for EPMA v. 14.0.6 also outputs your secondary boundary fluorescence parameters to the log window when displaying the sample raw data from the Analyze! window:



In addition, the Report button now outputs references for the secondary boundary fluorescence correction (if specified) and also for the Bragg defocus correction (if selected):