Probe Software Users Forum
General EPMA => EPMA (and SEM) Education and Training => Topic started by: Probeman on November 07, 2016, 11:34:30 AM
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This year and last year my lab manager Julie Chouinard, has been utilizing the Probe for EPMA software in "demonstration mode" to teach students how to run the electron microprobe. She's had the students install the software on their laptops so they can practice setting up runs using the "demo" mode that is enabled by default when installing the software on a new computer.
Her main goal was to reduce time spent actually on the instrument for training new users, but recently, several students have told me that working with the software on their laptops has been a big help in learning the technique in general. I originally developed the demo mode just for my own testing, but I think it could be a good tool for teaching as well. What do you all think?
If this is true maybe it makes sense to make the "demo" mode even more realistic. Right now one can acquire standards in "demo" mode and the software will automatically generate the correct intensities using the physics models in PFE. This allows students to "run" both primary and secondary standards for checking "accuracy" (by utilizing different matrix corrections) as described here:
http://probesoftware.com/smf/index.php?topic=508.msg2779#msg2779
On a related topic it should be mentioned that setting these parameters in the probewin.ini file
EDSSpectraInterfacePresent=1 ; non-zero EDS spectrum interface feature available (Thermo, Bruker, etc)
EDSSpectraInterfaceType=0 ; 0 = Demo, 1 = Edax, 2 = Bruker, 3 = Oxford, 4 = Unused, 5 = Thermo NSS, 6 = JEOL
EDSSpectraNetIntensityInterfaceType=0 ; 0 = Demo, 1 = Edax, 2 = Bruker, 3 = Oxford, 4 = Unused, 5 = Thermo NSS, 6 = JEOL
Allows one to also automatically acquire EDS spectra based on the actual composition, e.g., standards, using the Penepma Monte Carlo software that is automatically installed by the CalcZAF installer, as seen here:
http://probesoftware.com/smf/index.php?topic=481.msg5267#msg5267
Unfortunately I still don't have a "demo" code for stripping the background to get net intensities for EDS elements, yet... but it occurs to me that if using PFE in "demo" mode is an effective method for teaching EPMA to students and/or new users, I wonder if making the PFE "demo" even more realistic would be a good idea...
For example, currently the wavecan acquisition in "demo" mode just shows a single large analytical peak (based on the actual element concentration!), but no other secondary peaks, or peaks from other elements. But I realized that if I utilize the code that I wrote to generate the Monte Carlo EDS spectra, and convolve it as higher resolution for WDS, all the peaks would be there. I have to think about how I would add higher order Bragg reflections to this Monte-Carlo spectrum, but even just the first order lines would be more realistic for teaching.
What do you all think of this? Would using a more realistic "demo" mode in PFE be useful for teaching students and/or new users?
john
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I just thought of one small "fly in the ointment" for utilizing Penepma Monte Carlo calculations for accurate "demo" mode wavescans. And that is that while this method works fine for EDS demo mode acquisitions (because as the calculation statistics improve, the full EDS spectrum is updated during the acquisition), but in the case of WDS scans, the Monte Carlo calculation will be proceeding as the WDS scan proceeds, meaning that the beginning portion of the scan will have considerably worse statistics than the later WDS points, since WDS points are acquired serially... I have to think more about this.
Maybe I should simply pre-calculate 100 pure element spectra using Penepma and then simply synthesize them for the material in question...? With some correction for matrix effects. A bit brute force, but at least no further Monte Carlo calculations are required. Obviously, the beam energy is a factor that needs to be dealt with, but we could start with 15 keV and go from there...
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Maybe I should simply pre-calculate 100 pure element spectra using Penepma and then simply synthesize them for the material in question...? With some correction for matrix effects. A bit brute force, but at least no further Monte Carlo calculations are required. Obviously, the beam energy is a factor that needs to be dealt with, but we could start with 15 keV and go from there...
I believe that "synthesizing" demonstration wavescans in real time by utilizing 100 pure elements spectra pre-generated by Penepma will be the way to go forward on this. At least it will be a fun project for the holidays... so with that in mind, I've started Monte Carlo calculations of all pure elements in Penepma running one of my servers to an arbitrary level of precision (~40 hours per element).
I'll have to convolve the Penepma spectral resolution as a function of Bragg crystal 2d (and possibly spectrometer position) and also figure a way to generate higher order reflections as well... should be interesting!
john
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The latest version of PfE, now displays realistic PHA scans in *demo mode* both for traditional PHA scans, and Cameca MCA PHA scans as seen here:
(https://probesoftware.com/smf/gallery/1_22_11_16_5_24_08.png)
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Can anyone tell me roughly what the FWHM in eV is for the basic Bragg crystal types? The book I think it might be in, is at my UofO office and I'm working at Probe Software today!
I realize WDS spectral resolution varies over the spectrometer range, for example, the lower spectrometer angles yield worse spectral resolution because the angle of diffraction is lower (more grazing) and therefore fewer crystal lattice layers are involved in the diffraction. But I only need rough numbers...
So in eV, what are the rough spectral resolutiuon for these Bragg crystals in eV? Or any units for that matter!
LIF:
PET:
TAP:
PC0:
PC1 or LDE1:
etc.
Thanks,
john
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I am actually in the process of extracting this information from the many demo data that I got, so hopefully can provide you with some numbers. But what is the book that you are thinking of? I may have it at hand.
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I am actually in the process of extracting this information from the many demo data that I got, so hopefully can provide you with some numbers. But what is the book that you are thinking of? I may have it at hand.
Hi Anette,
It's a small, slim volume with an orange book sleeve. I think it was called something like "Principles of X-ray Spectrometery" or a variation on that.
john
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Hi John,
I only have a slim orange volume for "Electron Beam Analysis" and it does not list it. However I could pull the numbers from Virtual WDS. I picked one element at the high and the low range for each crystal type Let me know if you need any others one in particular.
TAP F: 0.0012
TAP Si: 0.0019
PET Si: 0.0012
PET Mn: 0.0023
LIF Ca: 0.0012
LIF Fe: 0.0013
LIF Br: 0.0021
LDE1 C: 0.0012
LDE1 F: 0.0018
LDE2 B: 0.0012
LDE2 N: 0.0016
I guess the unit is keV
Btw, even if you don't have Virtual WDS, you can get a trial version if you want to peruse it yourself.
Hope this helps for now.
Cheers,
Anette
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TAP F: 0.0012
TAP Si: 0.0019
PET Si: 0.0012
PET Mn: 0.0023
LIF Ca: 0.0012
LIF Fe: 0.0013
LIF Br: 0.0021
LDE1 C: 0.0012
LDE1 F: 0.0018
LDE2 B: 0.0012
LDE2 N: 0.0016
I guess the unit is keV
Hi Anette,
This can't be correct. For example, I know that LIF has better resolution than TAP, but this table has them being all about the same. And certainly the multi-layer diffractors are *much* lower resolution than even TAP. Just think about F Ka on TAP vs. LDE1.
See Ti Ka scanned on LIF and PET attached below. The LIF scan is clearly resolving at higher resolution. In fact if I plot them in keV units I see FWHM values around 27 eV for PET and 11 eV for LIF.
john
PS I guess I partially answered my own question! But I'd be interested if anyone has actually measured these themselves for the other crystals, TAP, LDE/PC...
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See Ti Ka scanned on LIF and PET attached below. The LIF scan is clearly resolving at higher resolution. In fact if I plot them in keV units I see FWHM values around 27 eV for PET and 11 eV for LIF.
When I guesstimate FWHM for Ti Ka1 measured using LiF with 550-micron detector slit (see plot below), I get ~3.7 eV (and ~5.0 eV for Ba La1). I've also attached the original Excel file, which contains a molybdenite WDS/PET versus EDS example as well. I haven't compared with results from large-area and "high intensity" crystals.
(https://probesoftware.com/smf/gallery/381_02_12_16_6_46_23.bmp)
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See Ti Ka scanned on LIF and PET attached below. The LIF scan is clearly resolving at higher resolution. In fact if I plot them in keV units I see FWHM values around 27 eV for PET and 11 eV for LIF.
When I guesstimate FWHM for Ti Ka1 measured using LiF with 550-micron detector slit (see plot below), I get ~3.7 eV (and ~5.0 eV for Ba La1). I've also attached the original Excel file, which contains a molybdenite WDS/PET versus EDS example as well. I haven't compared with results from large-area and "high intensity" crystals.
That is much closer to what I would expect. In fact my Ti Ka scan on LIF shows both the Ka1 and Ka2, so my FWHM guess is wider than it should be.
And if I plot it in keV space and measure more carefully above the Ka1 Ka2 split, I get about 5 eV for the Ti ka FWHM which is closer to your guess:
(https://probesoftware.com/smf/gallery/395_02_12_16_9_59_59.png)
john
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When I guesstimate FWHM for Ti Ka1 measured using LiF with 550-micron detector slit (see plot below), I get ~3.7 eV (and ~5.0 eV for Ba La1).
Very good guesstimate. I get 3.2 eV for Ti ka and 4.8 eV for Ba La on Brian's data (thanks for providing the raw data).
(https://probesoftware.com/smf/gallery/17_07_12_16_11_29_07.png)
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I am slowly making my way through my wavescans. I hope I can give a proper list soon.
(https://probesoftware.com/smf/gallery/17_07_12_16_11_37_59.png)
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Anette and Brian,
I am doing something wrong or there is something very different between JEOL and Cameca spectrometers (the Cameca spectrometers have just a fixed slit which makes it easier to test for one thing!).
I simply went into the PFE Plot! window, selected the wavescan and then clicked the kilovolts option for the x-axis and for PET I get this:
(https://probesoftware.com/smf/gallery/395_08_12_16_9_25_16.png)
Note that the Si Ka satellite lines are well resolved away from the main Si Ka peak! Using the mouse cursor the display indicates a FWHM of ~0.002 keV or ~2 eV. If I now plot the same peak using TAP I get this:
(https://probesoftware.com/smf/gallery/395_08_12_16_9_24_58.png)
Note that the Si Ka satellite lines on PET are now convolved *with* the Si ka main peak! And the Si Kb line is now visible!
Again using the mouse cursor data control I estimate the FWHM at 0.01 or ~ 10 eV.
Could the JEOL and Cameca spectrometers really have this much difference for PET and TAP? Do you two have any scans of Si Ka like this?
Anette: please try the kilovolts option in the PFE Plot! window and see what you get. I've attached the MDB file below if you want to play with my data in PFE.
This is very strange.
john
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Hi John,
Below is a comparison of scans across the Si Ka peak that I collected on "pure" Si using TAP and PETL crystals; I used the 550 and 500 micron detector slits, respectively. I tend to leave the slits in the 500/550 micron position (tab lifted fully) over the long term because 1) I don't really like sticking the "screwdriver" into the spectrometers except for crystal alignments, 2) sometimes the tab doesn't lock securely into the desired position, and 3) this slit provides a good balance between resolution and count rate. For Si Ka on PETL, I get FWHM = 2.34 eV, and, for Si Ka on TAP, I get FWHM = 6.78 eV.
(https://probesoftware.com/smf/gallery/381_08_12_16_1_42_12.bmp)
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Below is a comparison of scans across the Si Ka peak that I collected on "pure" Si using TAP and PETL crystals; I used the 550 and 500 micron detector slits, respectively. I tend to leave the slits in the 500/550 micron position (tab lifted fully) over the long term because 1) I don't really like sticking the "screwdriver" into the spectrometers except for crystal alignments, 2) sometimes the tab doesn't lock securely into the desired position, and 3) this slit provides a good balance between resolution and count rate. For Si Ka on PETL, I get FWHM = 2.34 eV, and, for Si Ka on TAP, I get FWHM = 6.78 eV.
Hi Brian,
Thanks. That seems very reasonable.
The good news is that because the Convolg code that comes with Penepma (which I am using to convolve these spectra), express FWHM as a function of energy, so as the energy of the spectrum increases (that is, Bragg angle gets smaller), the convolved resolution will correspondingly get worse just as one would expect in a Bragg spectrometer at lower angles, simply by using a constant for the resolution in the Convolg code. :)
john
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By the way, I'm not sure if most people realize that when Probe for EPMA is in "demo" mode, and you have the demo EDS mode specified in the Probewin.ini file:
[hardware]
EDSSpectraInterfacePresent = 1
EDSSpectraInterfaceType = 0
Probe for EPMA will acquire EDS spectra (using Penepma running in the background), and display the actual EDS spectra calculated for the standard composition specified or a random composition for the unknown. I think this could be useful for teaching, though at the moment one still has to utilize the Thermo or Bruker interface for obtaining net intensities for quantification (though we may have an "internal" spectrum peak stripping routine soon for quantification in demo mode).
See attached images below (you must be logged in to see attachments).
john
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I'm making progress on the Penepma WDS simulation mode in Probe for EPMA. The simulation is still quite crude so I'm not releasing it yet, but I think with another few days of work it will be ready to use by all. Note that you will need to update your Penepma download before you can utilize the simulation feature. I will announce when this Penepma update is ready to download.
Here (attached below- remember to login to see attachments!) are a couple examples of a simulated wavescan of the NIST K-411 minerals glass on a couple of spectrometers (TAP and LIF). Basically this merely tests the agreement between the NIST x-ray database and the Penepma x-ray database for the emission line energies (and my higher Bragg order reflections and refractive index correction calculations!).
But the resolution of the Fe Ka1 and Ka2 looks quite realistic to me! I foresee a couple of benefits of this simulation mode:
1. Because Probe for EPMA has a very generous license (once one buys a copy for their instrument, all users of that instrument may copy the software on as many computers as they like for their own use), the software can be used to teach EPMA off-line without consuming time on the actual instrument. My own lab manager has the students install the software on their laptops, and I have to say, when they show up for a lab practical, they already pretty much know how to run the instrument!
This saves a lot of time (and money!).
2. Also, regular users and operators can create accurate analytical setups off-line, for example with off-peaks already adjusted to avoid off-peak interferences. Be aware that because Penepma only calculates singly ionized atoms, no satellite emission lines will be visible in the simulated spectra, but the NIST KLM markers will still show their locations.
This could also save time (and money!).
OK, back to work!
john
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I need the favor of a sanity check. I'm wondering if the Bragg crystals on my instrument are deteriorating also (for the higher order reflections).
In modeling the above WDS simulations based on Penepma spectra, I performed some scans on my Sx100. Here is a scan of the NIST K-411 glass over the full range of a LTAP crystal:
(https://probesoftware.com/smf/gallery/1_30_12_16_3_58_03.png)
For some reason I seem to remember that the higher order reflections were stronger when I got the instrument some 8 years ago. Does anyone have a similar scan on a mineral glass over the full range of a TAP spectrometer? JEOL or Cameca flow detector, 15 keV, 4 sec per point, 2400 points.
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Another thought occurs to me: EDS detectors are usually at a fixed distance from the sample, but for WDS spectrometers, there is obviously a large decrease in geometric efficiency as the spectrometer is driven to high sin thetas and the distance to the sample increases.
That's a simple enough math problem, but there's a complication: the crystal is essentially perpendicular to the sample at high sin thetas, but tilts as it approaches the sample at lower sin thetas, therefore it presents a smaller area to the x-rays coming from the sample. This is decrease in "aspect" geometric efficiency is inverse, compared to the increase in geometric efficiency from decreasing the distance to the sample at lower sin thetas.
I'm not sure how to calculate this change in geometric efficiency as a function of sin theta. Has anyone stumbled a cross a table or plot of this change in WDS geometric efficiency that I could use for my WDS simulation code?
john
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The coding for the WDS simulation is very interesting. For example, here is a calculated spectrum for a NIST mineral glass plotted in eV space for an LDE/PC crystal:
(https://probesoftware.com/smf/gallery/1_31_12_16_10_37_21.png)
Looks weird right? But if we plot this same spectrum as a function of sin theta and add some noise, as seen here:
(https://probesoftware.com/smf/gallery/1_31_12_16_10_37_42.png)
It almost looks fairly correct. Here is the FWHM equation I had to use in the Penepma Convolg.f code (it could use an even larger exponent!):
C **** Example of FWHM(E) function for a WDS LDE spectrometer (~10 eV at 512 eV)
FWHM=0.000000001D0*E**3.7
Here is an example of a K-412 glass simulated on a "JEOL" instrument for the different spectrometers (see attached images below). I hope to be able to release this this weekend for general use though it still needs some tweaking to improve the modeling accuracy, e.g., non-linearity of the spectral resolution and geometric efficiency, etc.
john
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Ok, I got the WDS Penepma simulation working well enough I think for general use, though it still needs some tweaking as you will see.
First of all I should remind you that you will need to update Probe for EPMA (from the Help | Update Probe for EPMA menu) to v. 11.7.6 and also a second update of the Penepma files (also from the Help | Update Probe for EPMA menu, but be sure to check the Update Penepma Monte Carlo Files Only checkbox).
Second, there is no matrix (de)correction in these simulations yet, nor have I added Ar and Xe absorption edges from the detectors.
Third, Probe for EPMA will automatically revert back to the old demo mode, if any elements in the simulation have not yet been calculated. I've done about 2/3 of the pure elements so far (at 15 keV), but am continuing simulations of the remaining elements and also at 10 keV and 20 keV.
Fourth, Probe for EPMA will also utilize the WDS simulation data for off-peak measurements (the WDS simulation intensity scans are normalized to the calculated peak intensity, so they still work for quantification), but that means you can now get off-peak interferences in this new simulation mode! ;D
So, let's compare some simulated scans to actual scans on my Sx100 instrument (15 keV, 30 nA, 4 seconds per point, 2400 points). First let's look at a TAP crystal on Mg2SiO4. Here is the experimental scan:
(https://probesoftware.com/smf/gallery/1_31_12_16_3_57_50.png)
Now here is a simulated scan on Mg2SiO4:
(https://probesoftware.com/smf/gallery/1_31_12_16_3_59_12.png)
Not too bad! Especially since I only "simulated" the scan at 0.2 seconds per point!
Yes, the tail shapes are wrong because the convolution software (Penepma/Convolg) only does a Gaussian convolution at the present time, but still not too bad!
I'll post some more examples in a bit, but Barb wants me to help with the New Year's Eve party preparations! In the meantime I'll run the simulation at 4 seconds per point so the statistics are more comparable.
john
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Note that if for some reason you decide you don't want to utilize the new Penepma WDS simulation mode (for example, because you don't want to wait 10 to 30 seconds for the spectra simulation to be calculated), you can turn the Penepma spectrum simulation mode off (and/or back on) in the Acquire! window Acquisition Options dialog as seen here:
(https://probesoftware.com/smf/gallery/1_01_01_17_12_33_16.png)
Note also that PFE doesn't re-calculate new spectra unless a different standard is selected, or the keV or analyzed (or specified) elements have changed, or it's an unknown or wavescan sample and no spectra have been calculated yet.
This means if you acquire a data point on a standard, PFE calculates new spectra for each analyzed element (unless it's the same standard). Then if you start a new unknown or wavescan sample, the program will utilize the previously calculated standard spectra for the subsequent unknown or wavescan acquisition.
If a standard spectra has not yet been calculated, PFE will calculate a spectrum based on a random composition using the current analyzed (and specified) elements.
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I should also mention that Probe for EPMA also utilizes this Penepma WDS simulation mode for the spectrometer peaking as seen here:
(https://probesoftware.com/smf/gallery/1_01_01_17_12_47_52.png)
Here's a good joke you can play on an unsuspecting user: temporarily edit the probewin.ini file so the InterfaceType = 0 for demonstration mode and then let the student try to set up a probe run on the instrument! ;D
See how long it takes them to realize that they're in simulation mode! :P
john
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OK, here are some comparisons I promised between simulation and experimental. First here is a scan from my SX100 of the NIST K-411 glass on LIF:
(https://probesoftware.com/smf/gallery/1_01_01_17_4_29_16.png)
Now a simulation:
(https://probesoftware.com/smf/gallery/1_01_01_17_4_29_56.png)
Not too bad. Now a scan from my SX100 again on K-411 but of the PET crystal:
(https://probesoftware.com/smf/gallery/1_01_01_17_4_29_37.png)
And again a simulation:
(https://probesoftware.com/smf/gallery/1_01_01_17_4_30_24.png)
And here's the experimental and simulation without KLM markers:
(https://probesoftware.com/smf/gallery/1_01_01_17_4_43_19.png)
(https://probesoftware.com/smf/gallery/1_01_01_17_4_43_33.png)
I need to work a bit more on the peak widths and the intensities of the higher order reflections... and add Xe/Ar absorption edges. But I think it's very usable for teaching.
john
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Here's an example of the new EDS and WDS simulation code running together in JEOL demo mode:
(https://probesoftware.com/smf/gallery/1_03_01_17_11_00_00.png)
Sorry, I only had three WDS spectrometers running in this example!
john
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Here's an example of using the new WDS (off-line) simulation mode to find off-peak interferences.
Running a wavescan on a silicate standard we see the following graph in the Plot! window showing the K Ka III order line interfering with the default Mg ka off-peak position:
(https://probesoftware.com/smf/gallery/1_06_01_17_8_59_06.png)
After clicking the new position for the high side off-peak:
(https://probesoftware.com/smf/gallery/1_06_01_17_8_59_21.png)
I think this sort of thing could be useful for teaching EPMA off-line...
john
PS Here is a screen shot of the above run showing the WDS and EDS (and quant) simulation:
(https://probesoftware.com/smf/gallery/1_06_01_17_9_11_47.png)
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This seems so obvious in hindsight and I really can't think of a reason why I didn't think of it before (except that I am a bit "slow of study"), but I just realized that we *can* implement an EDS quantification for the Penepma Monte Carlo EDS simulation in Probe for EPMA!
Yes, this method is not a peak stripping deconvolution method (though a colleague of ours is working on that, and still it's worth doing just to better teach the parameters involved in peak shape modeling!), but this implementation does allow students to perform integrated EDS and WDS (or just EDS!) quantification off-line in the classroom without an instrument.
What I just realized (smack on forehead!), is that by merely saving the net intensity results (in the pe-intens-01.dat file) from the Penepma simulation to a database table in PFE (and background intensities from the pe-bremss.dat file), I can simply match up the requested element by EDS to this already saved table and get the net intensity for that element!
Of course if you are actually on the instrument with a student, you would be utilizing the Thermo or Bruker EDS interface for getting your EDS net intensities, but this method works off-line on other computers for Penepma simulated EDS spectra. This means that every student in your probe class can perform these simulated EDS-WDS acquisitions and quantifications on their own laptops without wasting time on the actual instrument!
Pretty cool! However, precision (actually poor accuracy due to low precision), is an issue with short EDS count times when using Penepma for Monte Carlo simulations. It's a FORTRAN physics package that follows every photon for a full accounting of fluorescence effects... and remember, Monte Carlo simulation isn't as "productive" electron path-wise, as instrumental measurements from your lab! Here is a comparison of the same Penepma simulation secondary standard acquired with 40 sec, 160 sec and 640 sec EDS counting times, and the resulting quant (the Mn and O are specified as fixed concentrations):
St 162 Set 2 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg Al Ca Mn O SUM
20 30.713 11.209 9.329 .000 9.680 .077 43.558 104.566
21 30.418 11.252 9.276 .000 9.621 .077 43.558 104.202
AVER: 30.565 11.231 9.303 .000 9.650 .077 43.558 104.384
SDEV: .208 .030 .037 .000 .041 .000 .000 .257
SERR: .147 .021 .026 .000 .029 .000 .000
%RSD: .68 .27 .40 .29 .43 .00 .00
PUBL: 25.382 11.209 8.847 .053 11.057 .077 43.558 100.183
%VAR: 20.42 .19 5.15 -100.00 -12.72 .00 .00
DIFF: 5.183 .022 .455 -.053 -1.407 .000 .000
STDS: 14 160 12 160 160 --- ---
Not great accuracy, but the Monte Carlo simulation only ran for 40 seconds! By the way, I'm not introducing any additional synthetic "noise" into these EDS calculations... I'm storing but not yet utilizing the uncertainty values from the pe-intens-01.dat file...
Now again on the same secondary standard (both primary and secondary standards re-required with 160 sec Monte Carlo simulation time):
St 162 Set 3 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg Al Ca Mn O SUM
30 25.712 11.636 7.662 .056 11.678 .077 43.558 100.380
31 25.777 11.664 7.658 .056 11.582 .077 43.558 100.372
AVER: 25.745 11.650 7.660 .056 11.630 .077 43.558 100.376
SDEV: .046 .020 .003 .000 .068 .000 .000 .006
SERR: .032 .014 .002 .000 .048 .000 .000
%RSD: .18 .17 .04 .09 .58 .00 .00
PUBL: 25.382 11.209 8.847 .053 11.057 .077 43.558 100.183
%VAR: 1.43 3.93 -13.41 5.13 5.19 .00 .00
DIFF: .363 .441 -1.187 .003 .573 .000 .000
STDS: 14 160 12 160 160 --- ---
Much better accuracy now with about a 160 sec (2.5 minute) simulation!
And here again with 640 sec simulation time (both primary and secondary standards "re-acquired"):
St 162 Set 4 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg Al Ca Mn O SUM
40 26.027 9.965 8.763 .099 11.309 .077 43.558 99.798
41 26.033 9.973 8.765 .099 11.311 .077 43.558 99.815
AVER: 26.030 9.969 8.764 .099 11.310 .077 43.558 99.807
SDEV: .004 .005 .001 .000 .002 .000 .000 .012
SERR: .003 .004 .001 .000 .001 .000 .000
%RSD: .02 .05 .02 .02 .01 .00 .00
PUBL: 25.382 11.209 8.847 .053 11.057 .077 43.558 100.183
%VAR: 2.55 -11.06 -.94 86.34 2.29 .00 .00
DIFF: .648 -1.240 -.083 .046 .253 .000 .000
STDS: 14 160 12 160 160 --- ---
Fe is the least accurate, but that makes sense as it will be a lower intensity emission line at 15 keV. Actually I'm impressed how good the quant is. Normally we expect Penepma to take 10 to 20 hours for precision approaching that of a normal EPMA instrument. Limiting the minimum energy to 1 keV will help even more (but then one won't see the oxygen peak in the simulated spectra!).
Remember, to utilize this new EDS-WDS simulation and full quantification feature you will need to update PFE to v. 11.7.9 from the Help menu and then also update your Penepma files from the help menu (with the Update Penepma Monte Carlo Files Only checkbox checked).
I'd be very interested in what you all think. Oh, by the way, in the throws of this simulation coding I implemented a method that allows one to specify different EDS (and CL) acquisition times for automation on a per sample basis. It even allows changing the EDS (and CL) count time on a per line basis with manually acquired samples.
john
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Last night I ran some EDS simulation acquisitions for 3600 sec each. Here is a quant from one of the secondary standards:
St 162 Set 1 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg Al Ca Mn O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: EDS EDS EDS EDS EDS
TIME: 3600.00 3600.00 3600.00 3600.00 3600.00 --- ---
ELEM: Si Fe Mg Al Ca Mn O SUM
10 25.694 10.963 9.049 .059 10.831 .077 43.558 100.231
11 25.706 10.952 9.046 .059 10.836 .077 43.558 100.235
AVER: 25.700 10.958 9.047 .059 10.834 .077 43.558 100.233
SDEV: .009 .008 .002 .000 .003 .000 .000 .003
SERR: .006 .006 .001 .000 .002 .000 .000
%RSD: .04 .07 .02 .77 .03 .00 .00
PUBL: 25.382 11.209 8.847 .053 11.057 .077 43.558 100.183
%VAR: 1.25 -2.24 2.27 11.63 -2.02 .00 .00
DIFF: .318 -.251 .200 .006 -.223 .000 .000
STDS: 14 160 12 160 160 --- ---
As you can see, the accuracy is close to that from normal EDS measurements. Note that I'm *not* suggesting that anyone needs to run their EDS simulations that long for teaching purposes, just that if you do, the accuracy is closer to what one would expect.
Next I modified the Penepma minimum energy in PFE from 400 eV to 1000 eV and ran the standards again. Here are results using 400 eV at 160 sec:
St 162 Set 7 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg Al Ca Mn O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: EDS EDS EDS EDS EDS
TIME: 160.00 160.00 160.00 160.00 160.00 --- ---
ELEM: Si Fe Mg Al Ca Mn O SUM
67 25.771 11.891 7.673 .055 11.692 .077 43.558 100.716
68 25.706 12.182 7.661 .055 11.353 .077 43.558 100.591
AVER: 25.738 12.036 7.667 .055 11.522 .077 43.558 100.654
SDEV: .046 .206 .009 .000 .240 .000 .000 .088
SERR: .033 .146 .006 .000 .170 .000 .000
%RSD: .18 1.71 .11 .10 2.08 .00 .00
PUBL: 25.382 11.209 8.847 .053 11.057 .077 43.558 100.183
%VAR: 1.40 7.38 -13.34 3.53 4.21 .00 .00
DIFF: .356 .827 -1.180 .002 .465 .000 .000
STDS: 14 160 12 160 160 --- ---
And here are results using the same 160 sec counting (simulation) time, but with the minimum energy set to 1000 eV (1 keV):
St 162 Set 8 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg Al Ca Mn O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: EDS EDS EDS EDS EDS
TIME: 160.00 160.00 160.00 160.00 160.00 --- ---
ELEM: Si Fe Mg Al Ca Mn O SUM
75 25.163 11.396 8.323 .062 11.595 .077 43.558 100.174
76 25.169 11.396 8.323 .062 11.595 .077 43.558 100.181
AVER: 25.166 11.396 8.323 .062 11.595 .077 43.558 100.178
SDEV: .005 .000 .000 .000 .000 .000 .000 .005
SERR: .003 .000 .000 .000 .000 .000 .000
%RSD: .02 .00 .00 .00 .00 .00 .00
PUBL: 25.382 11.209 8.847 .053 11.057 .077 43.558 100.183
%VAR: -.85 1.67 -5.92 17.73 4.87 .00 .00
DIFF: -.216 .187 -.524 .009 .538 .000 .000
STDS: 14 160 12 160 160 --- ---
Obviously, this sort of statistical testing requires many more replicates, but it seems reasonable that by merely setting the Penepma minimum electron energy to 1.0 (keV) in the Probewin.ini file, one can get better accuracy with the Penepma EDS simulation in PFE. Of course, the downside is that you won't see any peaks less than 1 keV (e.g., O Ka), but for teaching purposes it might suffice, especially for "geological" simulations where one isn't measuring oxygen anyway!
Right now changing this Penepma Minimum Electron Energy value requires an edit of the value in the Probewin.ini file, but in the next update later this week, I will add this field to the Acquisition Options dialog so it can be edited during a "run"...
john
-
Here's the new Penepma WDS and EDS simulation parameters in the Acquisition Options dialog:
(https://probesoftware.com/smf/gallery/1_09_01_17_10_06_35.png)
I also updated the Penepma distribution to include more pure element spectra for WDS simulation, so feel free to update your Penepma files again from the Help menu.
john
-
Another thought occurs to me: EDS detectors are usually at a fixed distance from the sample, but for WDS spectrometers, there is obviously a large decrease in geometric efficiency as the spectrometer is driven to high sin thetas and the distance to the sample increases.
That's a simple enough math problem, but there's a complication: the crystal is essentially perpendicular to the sample at high sin thetas, but tilts as it approaches the sample at lower sin thetas, therefore it presents a smaller area to the x-rays coming from the sample. This is decrease in "aspect" geometric efficiency is inverse, compared to the increase in geometric efficiency from decreasing the distance to the sample at lower sin thetas.
I'm not sure how to calculate this change in geometric efficiency as a function of sin theta. Has anyone stumbled a cross a table or plot of this change in WDS geometric efficiency that I could use for my WDS simulation code?
john
I can provide some information on this: Detector efficiency is a combination of 3 factors: i) As John pointed out, the effective size of the crystal (solid angle) as it moves and tilts along the range, ii) crystal reflectivity, and iii) counter efficiency.
The solid angle can be calculated (see slide 33 in the attached pdf) but decreases fairly steadily from low to high angles. For the crystal reflectivity I've only found sketchy experimental data, but again generally decreases from high to low angles (slide 34). I only have half the curve for TAP, so if anyone has the complete curve for TAP I'd be interested to know what it does in the upper half of the range. Counter efficiency is itself a function of window absorption and gas absorption (slides 24 and 25). Slides 35 and 36 give the resulting intensities for Ka and La x-rays respectively, generated by extracting ideal peak intensity values for pure elements from Stephen Reed's Virtual WDS program so are based on experimental results from Cameca spectrometers. The La plot very nicely shows the effect of the Ar absorption edge.
-
Another thought occurs to me: EDS detectors are usually at a fixed distance from the sample, but for WDS spectrometers, there is obviously a large decrease in geometric efficiency as the spectrometer is driven to high sin thetas and the distance to the sample increases.
That's a simple enough math problem, but there's a complication: the crystal is essentially perpendicular to the sample at high sin thetas, but tilts as it approaches the sample at lower sin thetas, therefore it presents a smaller area to the x-rays coming from the sample. This is decrease in "aspect" geometric efficiency is inverse, compared to the increase in geometric efficiency from decreasing the distance to the sample at lower sin thetas.
I'm not sure how to calculate this change in geometric efficiency as a function of sin theta. Has anyone stumbled a cross a table or plot of this change in WDS geometric efficiency that I could use for my WDS simulation code?
john
I can provide some information on this: Detector efficiency is a combination of 3 factors: i) As John pointed out, the effective size of the crystal (solid angle) as it moves and tilts along the range, ii) crystal reflectivity, and iii) counter efficiency.
The solid angle can be calculated (see slide 33 in the attached pdf) but decreases fairly steadily from low to high angles. For the crystal reflectivity I've only found sketchy experimental data, but again generally decreases from high to low angles (slide 34). I only have half the curve for TAP, so if anyone has the complete curve for TAP I'd be interested to know what it does in the upper half of the range. Counter efficiency is itself a function of window absorption and gas absorption (slides 24 and 25). Slides 35 and 36 give the resulting intensities for Ka and La x-rays respectively, generated by extracting ideal peak intensity values for pure elements from Stephen Reed's Virtual WDS program so are based on experimental results from Cameca spectrometers. The La plot very nicely shows the effect of the Ar absorption edge.
Hi Mike,
Right now I'm only interested in the geometric efficiency of the Bragg crystal (solid angle) as a function of spectrometer position, so your slide 33 is perfect for my purposes. Thanks!
john
-
I recently improved the EDS (demo) simulation mode to produce more realistic count rates when the element in question is not produced within the simulation time. This is primarily for elements that are measured but not present in the simulated composition, e.g., Ti in pure SiO2, or trace elements that do not produce an emission in the allotted simulation time. See highlighted text below.
john
St 12 Set 6 MgO synthetic, Results in Elemental Weight Percents
ELEM: Si Fe Mg Ti Si Fe Mg Ti Ca O
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN LIN LIN EDS EDS EDS EDS
TIME: --- --- --- --- 120.00 120.00 120.00 120.00 --- ---
BEAM: --- --- --- --- 30.00 30.00 30.00 30.00 --- ---
ELEM: Si-D Fe-D Mg-D Ti-D Si Fe Mg Ti Ca O SUM
XRAY: (ka) (ka) (ka) (ka) (ka) (ka) (ka) (ka) () ()
21 --- --- --- --- .001 .008 60.309 .004 .140 39.693 100.155
22 --- --- --- --- .001 .009 60.181 -.001 .140 39.693 100.024
23 --- --- --- --- -.001 .000 60.336 .000 .140 39.693 100.168
AVER: --- --- --- --- .000 .006 60.275 .001 .140 39.693 100.115
SDEV: --- --- --- --- .001 .005 .082 .003 .000 .000 .080
SERR: --- --- --- --- .001 .003 .048 .002 .000 .000
%RSD: --- --- --- --- 410.99 87.44 .14 230.29 .00 .00
PUBL: n.a. n.a. n.a. n.a. .005 .008 60.280 n.a. .140 39.693 100.126
%VAR: --- --- --- --- -93.38 -28.90 (-.01) --- .00 .00
DIFF: --- --- --- --- -.005 -.002 (.00) --- .000 .000
STDS: --- --- --- --- 14 162 12 22 --- ---
If you haven't tried the new EDS and WDS simulation in PFE you should- just update PFE on any off-line computer in your lab or office or home, using the Help menu. Also update the Penepma files from the same Help menu dialog by checking the Update Penepma Monte Carlo Files Only checkbox.
Then (if the InterfaceType=0 in the Probewin.ini file) simply click Yes when asked "Do you want to connect to the instrument?" and then from the Acquire! window, add some WDS elements and/or check the acquire EDS acquisition checkbox under Acquisition Options. You will automatically acquire simulated WDS and/or EDS spectra.
-
Hi all,
With Xavier's help I figured out how to change the random seed for the EDS simulation using Penepma. Turns out that not only does one need to specifiy a different negative number for the seed, but the "RSEED" line in the Penepma input file needs to be *before* the the "TIME" line!
Anyway, now replicate points more accurately reflect the actual counting statistics for the EDS simulation as seen here:
St 160 Set 2 NBS K-412 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg O Ca Al Mn
TYPE: ANAL ANAL ANAL ANAL SPEC SPEC SPEC
BGDS: EDS EDS EDS EDS
TIME: 120.00 120.00 120.00 120.00 --- --- ---
BEAM: 30.01 30.01 30.01 30.01 --- --- ---
ELEM: Si Fe Mg O Ca Al Mn SUM
36 22.960 4.290 10.825 45.909 10.899 4.906 .077 99.866
37 20.849 8.305 10.669 44.633 10.899 4.906 .077 100.338
38 22.890 9.928 12.470 45.578 10.899 4.906 .077 106.748
AVER: 22.233 7.507 11.321 45.373 10.899 4.906 .077 102.317
SDEV: 1.199 2.902 .998 .662 .000 .000 .000 3.844
SERR: .692 1.676 .576 .382 .000 .000 .000
%RSD: 5.39 38.66 8.81 1.46 .00 .00 .00
PUBL: 21.199 7.742 11.657 43.597 10.899 4.906 .077 100.077
%VAR: 4.88 -3.03 -2.88 4.07 .00 .00 .00
DIFF: 1.034 -.235 -.336 1.776 .000 .000 .000
STDS: 14 162 12 14 --- --- ---
STKF: .4101 .0950 .4736 .2664 --- --- ---
STCT: 100.01 3.81 142.18 75.57 --- --- ---
UNKF: .1708 .0634 .0755 .1822 --- --- ---
UNCT: 41.66 2.55 22.66 51.69 --- --- ---
UNBG: .03 .00 .04 .12 --- --- ---
ZCOR: 1.3016 1.1854 1.4995 2.4908 --- --- ---
KRAW: .4166 .6672 .1594 .6839 --- --- ---
PKBG: 1450.95 575.62 529.20 439.17 --- --- ---
Remember, to get EPMA like statistics, one needs to run the Penepma EDS simulation some 10 or 15 minutes or more!
john
PS to utilize this new random seed feature, you will need to update your Penepma files using the Help | Update Probe for EPMA menu and check the box that says: Update Penepma Monte Carlo Files Only. And of course you'll need to update PFE again also.
-
I've improved the WDS simulation to now include detector absorption edges for Ar and Xe.
Here is an actual scan on my Sx100 on a pure synthetic zircon crystal:
(https://probesoftware.com/smf/gallery/1_18_01_17_12_05_06.png)
and here is a WDS simulation on the same synthetic zircon:
(https://probesoftware.com/smf/gallery/1_18_01_17_12_05_23.png)
Not too bad actually. Here is the experimental scan with the KLM markers for Si, O and Zr for reference:
(https://probesoftware.com/smf/gallery/1_18_01_17_12_08_12.png)
We're not seeing the satellite lines as expected, since Penepma only does singly ionized atoms, but good enough for teaching purposes!
john
-
One more thing I should point out: the WDS simulation in PFE makes a new composition whenever a new standard is selected. However, if the sample setup does not change, the program will utilize the same composition for unknowns and wavescans.
But, only if the sample setup has *not* changed. This means that not only must the keV be the same, but also the WDS elements and any specified (non-analyzed) elements. If the sample setup has changed, the program will synthesize a random composition based on the current WDS elements.
For example, in the above zircon standard, I added Zr as a specified element to the unknown (and wavescan) sample setups, because it is present in the composition, but is not one of the WDS elements being analyzed in the simulation.
That way, once the zircon standard has run, I simply create a new unknown (or wavescan), with the previously specified element Zr, and the program does not create a random unknown (or wavescan) composition for simulation, but instead utilizes the previous standard composition.
I hope that makes sense, please let me know if not.
john
-
Here's an EDS simulation of a NIST glass running the Penepma Monte Carlo with the random seed added:
St 160 Set 3 NBS K-412 mineral glass, Results in Elemental Weight Percents
ELEM: Si Fe Mg O Ca Al Mn
TYPE: ANAL ANAL ANAL ANAL SPEC SPEC SPEC
BGDS: EDS EDS EDS EDS
TIME: 600.00 600.00 600.00 600.00 --- --- ---
BEAM: 30.00 30.00 30.00 30.00 --- --- ---
ELEM: Si Fe Mg O Ca Al Mn SUM
53 21.126 8.607 11.594 44.923 10.899 4.906 .077 102.132
54 20.967 7.960 11.088 43.319 10.899 4.906 .077 99.216
55 21.034 6.699 12.027 43.500 10.899 4.906 .077 99.141
AVER: 21.042 7.755 11.570 43.914 10.899 4.906 .077 100.163
SDEV: .080 .970 .470 .878 .000 .000 .000 1.706
SERR: .046 .560 .271 .507 .000 .000 .000
%RSD: .38 12.51 4.06 2.00 .00 .00 .00
PUBL: 21.199 7.742 11.657 43.597 10.899 4.906 .077 100.077
%VAR: -.74 .17 -.75 .73 .00 .00 .00
DIFF: -.157 .013 -.087 .317 .000 .000 .000
STDS: 14 162 12 14 --- --- ---
Close to typical EPMA precision and accuracy in 600 sec (10 min) per point of simulation. And it will improve with faster CPUs.
-
Just for fun last night I ran 1200 sec per point with the EDS (and WDS) simulation methods and got very pretty looking data:
St 162 Set 1 NBS K-411 mineral glass, Results in Elemental Weight Percents
ELEM: Ti Mn Ca Fe Mg Al Si O
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL SPEC
BGDS: LIN LIN LIN LIN EDS EDS EDS
TIME: 30.00 30.00 30.00 30.00 1200.00 1200.00 1200.00 ---
BEAM: 29.99 29.99 29.99 29.99 29.99 29.99 29.99 ---
ELEM: Ti Mn Ca Fe Mg Al Si O SUM
21 .002 .079 10.964 11.394 8.981 .077 25.264 43.558 100.320
22 .032 .071 11.109 11.285 8.374 .090 25.345 43.558 99.864
23 .022 .080 10.953 11.395 8.688 .030 25.740 43.558 100.466
24 .003 .083 11.119 11.415 9.032 .045 24.684 43.558 99.939
25 -.018 .081 11.115 11.383 8.661 .038 25.107 43.558 99.925
AVER: .008 .079 11.052 11.374 8.747 .056 25.228 43.558 100.103
SDEV: .019 .005 .086 .051 .268 .026 .383 .000 .271
SERR: .009 .002 .038 .023 .120 .012 .171 .000
%RSD: 238.76 5.99 .77 .45 3.06 46.69 1.52 .00
PUBL: n.a. .077 11.057 11.209 8.847 .053 25.382 43.558 100.183
%VAR: --- 2.38 (-.04) 1.47 -1.13 5.61 -.61 .00
DIFF: --- .002 (.00) .165 -.100 .003 -.154 .000
STDS: 22 160 162 263 12 13 14 ---
Even the trace Al by EDS (simulation) looks quite good, better than actual EDS! :D
Remember, you will need to update PFE and the Penepma Monte Carlo files from the PFE Help menu to obtain these new simulation features.
-
The only trouble we sometimes run into when students install CalcZAF/Probe for EPMA on their laptops is that some of the larger windows (in particular the Automate! window in PFE), are a little bigger than what the default screen resolution can display.
I don't know much about the newer operating systems such as Windows 10, but on my Win 10 laptop which has a fairly large screen, I can see the enough of the Automate! window so it's not a problem. But some student laptop screens are smaller and the entire Automate! window doesn't display, so they can't reach the Run Selected Samples button at the bottom...
One might right click the top of the window, select Move and use the cursor keys to move the window around I guess, but does anyone have any better suggestions on what desktop or video card options should be modified to get a somewhat larger "virtual" desktop, so one can scroll the desktop a bit to see a little more on the sides and top/bottom of the visible desktop?
john
-
The latest Penepma12 update contains pure element spectra for all the rare earths and many actinides, so I tried a WDS simulation of a monazite composition.
(https://probesoftware.com/smf/gallery/395_31_01_17_9_13_20.png)
(https://probesoftware.com/smf/gallery/395_31_01_17_9_13_34.png)
Can you tell which one is experimental and which one is simulation?
john
-
One "feature/problem" of the WDS simulations synthesized from Penepma pure element spectra in PFE is that because the peaks are convolved using a simple Gaussian method, the long Lorentzian tails that we normally see in our scans are not present. This means that spectral overlaps are smaller than expected and most overlaps simply do not appear in these synthetic spectra as shown here in an example of the Ba-Ti overlap in benitoite (Ba-Ti silicate):
(https://probesoftware.com/smf/gallery/1_02_02_17_4_25_03.png)
These Lorentzian tails on the emission peaks are mostly from randomized recrystallization of micro domains in the Bragg analyzing crystals during the "polygonization" step in manufacturing where the Bragg crystals are thermally cycled to improve reflectivity... see the attached figure below for details (I cannot remember where I got this figure so please remind me if you recognize it, so I can properly attribute it).
However, our old nemesis (Pb La - As Ka) is still a significant interference even with these simulated Gaussian convolutions:
(https://probesoftware.com/smf/gallery/1_02_02_17_4_45_23.png)
john
-
If I run another simulation on benitoite, but this time using PET crystals for Ti and Ba, we get this:
(https://probesoftware.com/smf/gallery/1_02_02_17_6_07_09.png)
Notice how the La2 line is now convolved with the PET crystal, while it was quite well separated with the LIF crystal plot in the previous post. Still not a significant overlap due to a lack of the above mentioned Lorentzian tails, but maybe good enough for teaching?
john
-
As you know, Probe for EPMA, when run in "demo" mode (the keyword InterfaceType=0 in the probewin.ini file), can simulate both EDS and WDS spectra for performing spectrum simulations for teaching EPMA in the classroom.
The latest version of Probe for EPMA now has a complete set of pure element WDS spectrum simulations at 15 keV from the Penepma Monte Carlo software and is distributed in the Penepma12.zip update which can be downloaded using the Help menu in Probe for EPMA as described here:
http://probesoftware.com/smf/index.php?topic=366.msg1936#msg1936
These pure element spectra are utilized to synthesize WDS spectra for simulation of wavescans on compounds. I am currently running simulations also at 5, 10, 20 and 25 keV and many of these are already in the Penepma12.zip distributions though they are not 100% complete.
john
-
The latest version of Probe for EPMA now has additional menus to easily switch between JEOL and Cameca simulation modes as seen here:
(https://probesoftware.com/smf/gallery/1_19_05_17_11_19_29.png)
These menus are only available when the InterfaceType keyword in the Probewin.ini file is zero. The JEOL simulation mode is the default interface option in Probe for EPMA when PFE is installed the first time.
The idea being that you can distribute PFE to all your students in class and if necessary switch to Cameca simulation mode (and back again to JEOL simulation mode if desired), with a single menu click.
john
-
As you know, Probe for EPMA, when run in "demo" mode (the keyword InterfaceType=0 in the probewin.ini file), can simulate both EDS and WDS spectra for performing spectrum simulations for teaching EPMA in the classroom.
The latest version of Probe for EPMA now has a complete set of pure element WDS spectrum simulations at 15 keV from the Penepma Monte Carlo software and is distributed in the Penepma12.zip update which can be downloaded using the Help menu in Probe for EPMA as described here:
http://probesoftware.com/smf/index.php?topic=366.msg1936#msg1936
These pure element spectra are utilized to synthesize WDS spectra for simulation of wavescans on compounds. I am currently running simulations also at 5, 10, 20 and 25 keV and many of these are already in the Penepma12.zip distributions though they are not 100% complete.
john
Hi John,
I'm struggling to figure out how to get compound spectra - I have Si element but the wavescan is just for Si Metal. Standards added are plagioclase, hornblende etc
Thanks
Ben
-
As you know, Probe for EPMA, when run in "demo" mode (the keyword InterfaceType=0 in the probewin.ini file), can simulate both EDS and WDS spectra for performing spectrum simulations for teaching EPMA in the classroom.
The latest version of Probe for EPMA now has a complete set of pure element WDS spectrum simulations at 15 keV from the Penepma Monte Carlo software and is distributed in the Penepma12.zip update which can be downloaded using the Help menu in Probe for EPMA as described here:
http://probesoftware.com/smf/index.php?topic=366.msg1936#msg1936
These pure element spectra are utilized to synthesize WDS spectra for simulation of wavescans on compounds. I am currently running simulations also at 5, 10, 20 and 25 keV and many of these are already in the Penepma12.zip distributions though they are not 100% complete.
john
Hi John,
I'm struggling to figure out how to get compound spectra - I have Si element but the wavescan is just for Si Metal. Standards added are plagioclase, hornblende etc
Thanks
Ben
Hi Ben,
I really should add a special "pop up list" for the user to select which compound they want the wavescan or unknown sample to be based on! But I haven't been able to think of a "sexy" way to do it yet!
The idea is that for standard samples, the program knows exactly what the composition should be, but that is not the case for unknowns and wavescans. So what I do currently is assume the composition of the last standard for the next wavescan or unknown. And if that's not available, just calculate a random composition based on the currently analyzed elements.
The only caveat, is that if the unknown or wavescan doesn't have *exactly* the same elements (analyzed *and* specified) as the previous standard composition, the program will generate a random composition for the subsequent unknown or wavescan.
The easiest way to do that is to just assign to the unknown (or wavescan) sample all the elements present in the standard composition (that are not being analyzed for), as specified (not analyzed) elements using the Elements/Cations dialog.
Frankly it's more about the issue of the aesthetics of a "pop up" asking the user for the sample composition, that would only occur for these simulation modes, that is stopping me. Let me think a bit more about it...
john
-
Hi John,
Thanks matching elements to standard did it. Looks good.
In an earlier post you mention two uses
(1) Train people to use software
(2) Help assign background positions - when creating analytical setup.
I wonder if for (2) it would be better not to have it in the demonstration mode. Using an unknown setup and selecting a standard - a wavescan could be generated instantly without waiting for it to virtual flip crystal, run wavescan etc - (in demo mode when changing beam current this changes noise?). The wavescan could be created in the live version of the program alllowing background selection then analyse?
Ben
-
In an earlier post you mention two uses
(1) Train people to use software
(2) Help assign background positions - when creating analytical setup.
I wonder if for (2) it would be better not to have it in the demonstration mode. Using an unknown setup and selecting a standard - a wavescan could be generated instantly without waiting for it to virtual flip crystal, run wavescan etc - (in demo mode when changing beam current this changes noise?). The wavescan could be created in the live version of the program allowing background selection then analyse?
Hi Ben,
What an excellent idea!
Actually, this has sort of already been done using Sandrin Feig's EPMA method development tool:
http://probesoftware.com/smf/index.php?topic=743.0
But if I can think of a simple way to do it for "on-line" probe runs, it would be cool...
john
-
As you know, Probe for EPMA, when run in "demo" mode (the keyword InterfaceType=0 in the probewin.ini file), can simulate both EDS and WDS spectra for performing spectrum simulations for teaching EPMA in the classroom.
The latest version of Probe for EPMA now has a complete set of pure element WDS spectrum simulations at 15 keV from the Penepma Monte Carlo software and is distributed in the Penepma12.zip update which can be downloaded using the Help menu in Probe for EPMA as described here:
http://probesoftware.com/smf/index.php?topic=366.msg1936#msg1936
These pure element spectra are utilized to synthesize WDS spectra for simulation of wavescans on compounds. I am currently running simulations also at 5, 10, 20 and 25 keV and many of these are already in the Penepma12.zip distributions though they are not 100% complete.
john
Hi John,
I'm struggling to figure out how to get compound spectra - I have Si element but the wavescan is just for Si Metal. Standards added are plagioclase, hornblende etc
Thanks
Ben
Hi Ben,
I really should add a special "pop up list" for the user to select which compound they want the wavescan or unknown sample to be based on! But I haven't been able to think of a "sexy" way to do it yet!
The idea is that for standard samples, the program knows exactly what the composition should be, but that is not the case for unknowns and wavescans. So what I do currently is assume the composition of the last standard for the next wavescan or unknown. And if that's not available, just calculate a random composition based on the currently analyzed elements.
The only caveat, is that if the unknown or wavescan doesn't have *exactly* the same elements (analyzed *and* specified) as the previous standard composition, the program will generate a random composition for the subsequent unknown or wavescan.
The easiest way to do that is to just assign to the unknown (or wavescan) sample all the elements present in the standard composition (that are not being analyzed for), as specified (not analyzed) elements using the Elements/Cations dialog.
Frankly it's more about the issue of the aesthetics of a "pop up" asking the user for the sample composition, that would only occur for these simulation modes, that is stopping me. Let me think a bit more about it...
john
Hi Ben,
Ok, there is no caveat now with the latest version of PFE.
The simulation mode will now always use the composition of the last standard for subsequent unknowns or wavescans, as long as the takeoff, keV and analyzed elements do not change.
If the conditions change and a standard has not been simulated, the program will simulate a random unknown or wavescan composition until a standard has been simulated using the new conditions.
I think this makes it much more intuitive now, try it out please and let me know what you think. And thanks for your help.
john
-
Hi John,
Thanks that makes it easier.
Also I've found out what I was doing wrong. I created the standard - but did not acquire any counts on the standard. For it to work you have to create the standard and click 'start standard or unknown acquisition' to acquire counts. Before doing the wavescan.
All working & looks good thanks
Ben
-
I ran the simulation on a zircon - for a sample I already had an actual wavescan for at 17kV.
It does a very good job, shows the effect of absorption edge, and allows correct background selection - or use of Mb line. Plus when compare to xeno counter spec 4 see difference
Simulation green. Actual wavescan blue
(https://probesoftware.com/smf/gallery/453_10_08_17_7_22_12.png)
At 25kV - see simulation includes Zr La 5 order, for like wavelength tables, the reflectivity of crystals for high orders not none
(https://probesoftware.com/smf/gallery/453_10_08_17_7_24_50.png)
-
Hi Ben,
Cool.
I do add a correction in for higher orders, but I can't say I "tuned" it much.
One could spend a life time adjusting these parameters! Since it's only intended for teaching it's probably OK for now.
I hope you find the new simulation code easier to use now...
john
-
Also I've found out what I was doing wrong. I created the standard - but did not acquire any counts on the standard. For it to work you have to create the standard and click 'start standard or unknown acquisition' to acquire counts. Before doing the wavescan.
Hi Ben,
Yes, one has to let it calculate the simulated standard intensities first. That is you don't need to actually finish acquiring the standard data point, but you do need to let it run at least until it starts counting- then you could click cancel. That way the simulated standard intensities are calculated and stored for the next point or unknown or wavescan sample.
john
-
I ran the simulation on a zircon - for a sample I already had an actual wavescan for at 17kV.
It does a very good job, shows the effect of absorption edge, and allows correct background selection - or use of Mb line. Plus when compare to xeno counter spec 4 see difference
Simulation green. Actual wavescan blue
(https://probesoftware.com/smf/gallery/453_10_08_17_7_22_12.png)
At 25kV - see simulation includes Zr La 5 order, for like wavelength tables, the reflectivity of crystals for high orders not none
(https://probesoftware.com/smf/gallery/453_10_08_17_7_24_50.png)
Here is a comparison I did of higher order reflections. It does appear I could decrease their simulated intensity a bit:
http://probesoftware.com/smf/index.php?topic=837.msg5477#msg5477
john
-
I ran the simulation on a zircon - for a sample I already had an actual wavescan for at 17kV.
It does a very good job, shows the effect of absorption edge, and allows correct background selection - or use of Mb line. Plus when compare to xeno counter spec 4 see difference
Simulation green. Actual wavescan blue
(https://probesoftware.com/smf/gallery/453_10_08_17_7_24_50.png)
Hi Ben,
I worked a bit on the higher order Bragg reflection code and here is a simulated scan of U ma ROI on PET for a zircon composition (at 25 keV):
(https://probesoftware.com/smf/gallery/1_12_08_17_3_26_46.png)
I think this looks better.
By the way I also happened to also run a simulation of the Hf La region and here is a teaching opportunity to demonstrate to students why in zircon we prefer the Hf Ma line:
(https://probesoftware.com/smf/gallery/1_12_08_17_3_27_10.png)
In addition I ran a full spectrometer range simulation on the K-411 glass here (at 15 keV):
(https://probesoftware.com/smf/gallery/1_12_08_17_3_46_33.png)
and here is an experimental scan from my SX100:
(https://probesoftware.com/smf/gallery/1_12_08_17_3_27_28.png)
Not too bad I think. Good enough for teaching in the classroom I think.
The cool thing about this improved simulation mode in the latest PFE is that the students learn not only the theory and practice of EPMA without wasting time on the instrument, but also learn the actual software that they will be utilizing, for when they do get on the instrument!
I'll be uploading this improved simulation version tonight.
john
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Hi John,
Looks very good and I think in most cases could be used to select backgrounds -removing the need the timely wavescans.
Obviously the confidence will be less around high order interferences - where a real wavescan could be done if required - high order interferences cahnge from machine to machine - In the case of Fe La & Lb - have Fe 9th order - clearly visible on the cameca but not visible on the Jeol. I'm guessing (but haven't looked carefully) this is because Jeol sets Fe La to 4 volts, whereas on the Cameca Fe La will be set to 1-2 volts - so the 9th order remains in the spectra.
OOPS - I was wrong above - The difference between the Jeol and Cameca observed - was that the Jeol was running in differential mode with a fully open window (0.5-9.5volts; in which 9th order excluded) - which for some reason is not the same as running the Jeol in integral mode (in which 9th order occurs). The Cameca was in integral mode. The same may apply to Zr Ka V?
Any plans to include the distinction between L and H type?
Here are wavescans on Monazite
(https://probesoftware.com/smf/gallery/453_14_08_17_3_19_07.bmp)
Which give LIFL 9.4 eV FWHM for Ce Lb and Nd La
(https://probesoftware.com/smf/gallery/453_14_08_17_3_19_32.png)
And LIFH 17.71 ev FWHM
(https://probesoftware.com/smf/gallery/453_14_08_17_3_19_50.png)
(peak fit using Fityk)
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Hi John,
Looks very good and I think in most cases could be used to select backgrounds -removing the need the timely wavescans.
Obviously the confidence will be less around high order interferences - where a real wavescan could be done if required - high order interferences change from machine to machine - In the case of Fe La & Lb - have Fe 9th order - clearly visible on the Cameca but not visible on the Jeol. I'm guessing (but haven't looked carefully) this is because Jeol sets Fe La to 4 volts, whereas on the Cameca Fe La will be set to 1-2 volts - so the 9th order remains in the spectra.
Any plans to include the distinction between L and H type?
Hi Ben,
The difference in PHA voltage range between JEOL and Cameca is just a difference in gain (multiplication) convention so far as I know (that is, multiply a Cameca PHA scan by a factor of two and one should have a JEOL PHA scan). I also haven't looked at any differences between the higher order sensitivities between JEOL and Cameca either, but since you have both instruments, you are in an ideal position to do so!
What aspect of L and H type crystals(?) are you thinking of?
john
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Hi John,
Here are wavescans on Monazite
(https://probesoftware.com/smf/gallery/453_14_08_17_3_19_07.bmp)
What are these two scans being compared?
-
Sorry did I forget to say. Its REE in Monazite. LIFL in pink, LIFH in blue
Ben
-
What aspect of L and H type crystals(?) are you thinking of?
john
Hi John
So the H crystals have poorer resolution compared to the L crystals - due to the smaller rowland circle. Therefore they ideally would be given different energy resolutions
Ben
-
What aspect of L and H type crystals(?) are you thinking of?
john
Hi John
So the H crystals have poorer resolution compared to the L crystals - due to the smaller rowland circle. Therefore they ideally would be given different energy resolutions
Ben
Hi Ben,
Yeah, that could be done, but I suspect there are many other aspects where the wavescan simulation could be also be improved.
For example, currently I synthesize the wavescan by combining pure element Penepma spectra for pure elements at 1 eV resolution. Then I convolve the summed scans using the Convolg.exe FORTRAN app that comes with Penepma for each crystal type. At the time I tweaked the convolution resolution to get approximately WDS type peaks using the following equations:
C **** Example of FWHM(E) function for a WDS LIF spectrometer (~10 eV at 5898 eV)
FWHM=0.0000003D0*E**2.
C **** Example of FWHM(E) function for a WDS PET spectrometer (~14 eV at 3690 eV)
FWHM=0.0000008D0*E**2
C **** Example of FWHM(E) function for a WDS TAP spectrometer (~4 eV at 1500 eV)
FWHM=0.000000000005D0*E**3.9
C **** Example of FWHM(E) function for a WDS LDE spectrometer (~10 eV at 512 eV)
FWHM=0.000000001D0*E**3.7
I'm not saying these are correct, but they give reasonable looking results. The problem is that WDS resolution is extremely non-linear as a function of energy, and in fact has very high resolution at low energies and very low resolution at high energies, which is of course the opposite of EDS spectra! See an example of a WDS spectra plotted in eV space:
https://probesoftware.com/smf/index.php?topic=837.msg5476#msg5476
Then there is the question of peak shape. The Convolg.exe FORTRAN app assumes only a Gaussian peak, but in fact the WDS peak is a Gaussian-Lorentenzian, with greatly extended tails due to polygonization effects from the crystal produced during manufacturing as described here:
https://probesoftware.com/smf/index.php?topic=837.msg5592#msg5592
So, there is a lot that can be improved.
john
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Hi Ben,
Ok, there is no caveat now with the latest version of PFE.
The simulation mode will now always use the composition of the last standard for subsequent unknowns or wavescans, as long as the takeoff, keV and analyzed elements do not change.
If the conditions change and a standard has not been simulated, the program will simulate a random unknown or wavescan composition until a standard has been simulated using the new conditions.
I think this makes it much more intuitive now, try it out please and let me know what you think. And thanks for your help.
john
Hi John,
This works really well - you can even simulate analysis of samples for elements not present in the sample.
Ben
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The previous WDS Penepma simulation code I implemented a few months ago utilizes the last standard composition for simulation of wavescans or unknowns. But when running a bunch of wavescan simulations with different compositions, that method doesn't work very well, as it just utilizes the last standard composition that was run. So I've modified the Penepma WDS simulation code, so that if the unknown or wavescan has the same *name* as one of the standards in the run, the program will now automatically load that standard composition for simulation.
To facilitate this, I use the Positions window (from the Automate!, then Digitize window), as seen here:
(https://probesoftware.com/smf/gallery/1_30_12_17_5_38_19.png)
Using the buttons outlined in red, one merely selects the standard positions from the position database and then duplicates them to either unknown or wavescan position samples. Now one can automate realistic simulations of unknowns and wavescans based on specific standard compositions as seen here:
(https://probesoftware.com/smf/gallery/1_30_12_17_5_43_36.png)
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We've made another small improvement in addition to the above simulation of unknowns and wavescans based on the standard composition if the sample name matches that of a standard already in the run. This latest improvement automatically adds in oxygen by stoichiometry if the Calculate with Stoichiometric Oxygen option is selected in the Analyze! | Calculation Options dialog.
If this flag is in the default Calculate As Elemental option, and the unknown (or wavescan) sample is *not* using a sample name that is the same as a standard already in the run, the program will generate a random composition based on the currently analyzed elements as seen here:
Un 4 test as elemental, Results in Elemental Weight Percents
ELEM: Si Fe
BGDS: LIN LIN
TIME: 20.00 20.00
BEAM: 30.01 30.01
ELEM: Si Fe SUM
8 23.709 76.564 100.273
AVER: 23.709 76.564 100.273
SDEV: .000 .000 .000
SERR: .000 .000
%RSD: .00 .00
STDS: 14 26
However, with the latest code in version 12.1.3, if the Calculate with Stoichiometric Oxygen option is selected as seen here:
(https://probesoftware.com/smf/gallery/1_31_12_17_1_52_38.png)
the software will now correctly calculate a random *oxide* composition based on the current cation stoichiometry as seen here:
Un 11 test oxide, Results in Elemental Weight Percents
ELEM: Si Fe O
TYPE: ANAL ANAL CALC
BGDS: LIN LIN
TIME: 20.00 20.00 ---
BEAM: 30.03 30.03 ---
ELEM: Si Fe O SUM
18 14.537 53.817 31.981 100.334
AVER: 14.537 53.817 31.981 100.334
SDEV: .000 .000 .000 .000
SERR: .000 .000 .000
%RSD: .00 .00 .00
STDS: 14 26 ---
STKF: .4101 .6548 ---
STCT: 144.18 151.28 ---
UNKF: .1089 .4903 ---
UNCT: 38.27 113.29 ---
UNBG: .09 .40 ---
ZCOR: 1.3353 1.0975 ---
KRAW: .2655 .7489 ---
PKBG: 415.00 283.06 ---
And if the Display as Oxides checkbox is displayed, these results will also be displayed:
Un 11 test oxide, Results in Oxide Weight Percents
ELEM: SiO2 FeO O SUM
18 31.099 69.235 .000 100.334
AVER: 31.099 69.235 .000 100.334
SDEV: .000 .000 .000 .000
SERR: .000 .000 .000
%RSD: .00 .00 .00
STDS: 14 26 ---
Of course most of the time you'll probably want to enter an unknown (or wavescan) sample name that is the same as a standard already in the run (as described in the previous post), so that one will obtain a specific composition for teaching purposes. But the random composition code is there just in case one acquires an unknown (or wavescan) simulation and either the sample name doesn't match an existing standard or there are no standards in the run.
Either way, you'll get a reasonable composition with simulated statistics applied, also suitable for teaching! :)
-
As many of you know, Probe for EPMA has a very realistic demo or simulation mode which can be utilized for educational purposes.
Probe for EPMA utilizes spectral intensities generated from the Penepma Monte Carlo software in two different ways. First, for WDS simulation it utilizes previously calculated pure element spectra from Penepma calculated using 1 eV resolution in 5 keV steps from 5 to 25 keV. For compounds it simply sums the spectra based on the weight fraction of the element (Yes, we should also be performing an absorption correction on each energy bin, but it's on the to-do list. In the meantime it's good enough...) to produce the final WDS spectrum.
Of course the spectrum is subsequently modified for higher Bragg orders, WDS exponential effects and absorption edges. See the folder C:\UserData\Penepma12\Penepma\pure for these pure element intensity files. If you don't have these files, or you don't have a complete set of these files, you should update your Penepma data files using the Help | Update menu with the Update Penepma Monte Carlo Files Only checkbox checked.
For EDS, Probe for EPMA utilizes the Penepma in "real time", that is the EDS spectra is generated as the Penepma Monte Carlo program runs in the background and displayed in Probe for EPMA. The photon rate depends on a number of factors but is roughly equivalent to having a beam current of a few nA or so.
In a recent post Donovan showed an example demonstrating some new flags for EDS quantification and data was shown where the Fe concentration was not very accurate compared to the other elements as seen here:
ELEM: Si Ca Fe Mg Al Mn O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN EDS EDS EDS
TIME: 20.00 20.00 24.00 24.00 24.00 --- ---
BEAM: 30.02 30.02 30.02 30.02 30.02 --- ---
ELEM: Si Ca Fe Mg Al Mn O SUM
5 21.416 11.062 6.624 11.571 4.886 .077 43.597 99.234
AVER: 21.416 11.062 6.624 11.571 4.886 .077 43.597 99.234
SDEV: .000 .000 .000 .000 .000 .000 .000 .000
SERR: .000 .000 .000 .000 .000 .000 .000
%RSD: .00 .00 .00 .00 .00 .00 .00
PUBL: 21.199 10.899 7.742 11.657 4.906 .077 43.597 100.077
%VAR: 1.02 1.50 -14.44 (-.73) (-.41) .00 .00
DIFF: .217 .163 -1.118 (-.09) (-.02) .000 .000
STDS: 162 162 162 160 160 --- ---
This is primarily because of the poor counting statistics resulting from a relatively high energy emission line at 15 keV, only running the Penepma simulation for 12 seconds (it assumed an EDS count time of 12 seconds because of the assumed 50% EDS deadtime), and only a single "measurement". Here one can see the low count rate from the Fe Ka emission line from Penepma:
On-Peak (off-peak corrected) or EDS (bgd corrected) or MAN On-Peak X-ray Counts (cps/1nA) (and Faraday/Absorbed Currents):
ELEM: si ka ca ka fe ka mg ka al ka BEAM1 BEAM2
BGD: OFF OFF EDS EDS EDS
SPEC: 1 2 0 0 0
CRYST: PET LPET EDS EDS EDS
ORDER: 1 1 1 1 1
5G 56.93 33.28 2.82 22.62 9.75 30.016 29.974
AVER: 56.93 33.28 2.82 22.62 9.75 30.016 29.974
SDEV: .00 .00 .00 .00 .00 .000 .000
1SIG: .31 .24 .06 .18 .12
SIGR: .00 .00 .00 .00 .00
SERR: .00 .00 .00 .00 .00
%RSD: .00 .00 .00 .00 .00
However, if we increase the WDS counting time to 64 seconds we see a much better result as seen here:
ELEM: Si Ca Fe Mg Al Mn O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN EDS EDS EDS
TIME: 24.00 24.00 64.00 64.00 64.00 --- ---
BEAM: 30.03 30.03 30.03 30.03 30.03 --- ---
ELEM: Si Ca Fe Mg Al Mn O SUM
37 21.533 10.589 7.691 11.640 4.903 .077 43.597 100.030
AVER: 21.533 10.589 7.691 11.640 4.903 .077 43.597 100.030
SDEV: .000 .000 .000 .000 .000 .000 .000 .000
SERR: .000 .000 .000 .000 .000 .000 .000
%RSD: .00 .00 .00 .00 .00 .00 .00
PUBL: 21.199 10.899 7.742 11.657 4.906 .077 43.597 100.077
%VAR: 1.57 -2.85 -.66 (-.15) (-.05) .00 .00
DIFF: .334 -.310 -.051 (-.02) (.00) .000 .000
STDS: 162 162 162 160 160 --- ---
In fact, here we got lucky! Spurious accuracy as they say!
However, instead of increasing the EDS count time, we could simply acquire more data points per standard. Note that because PFE "re-seeds" the random number generator in Penepma for each spectrum "acquisition", the average will usually be more accurate than a single point. Of course, even better is to acquire multiple data points and a longer counting time as seen here:
ELEM: Si Ca Fe Mg Al Mn O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN EDS EDS EDS
TIME: 24.00 24.00 64.00 64.00 64.00 --- ---
BEAM: 30.01 30.01 30.01 30.01 30.01 --- ---
ELEM: Si Ca Fe Mg Al Mn O SUM
37 21.540 10.588 7.696 11.396 5.202 .077 43.597 100.098
38 21.430 10.739 7.906 11.129 4.779 .077 43.597 99.657
39 21.481 10.701 6.680 11.716 5.343 .077 43.597 99.595
40 21.296 10.845 7.757 11.773 4.451 .077 43.597 99.796
41 21.675 10.843 7.908 11.969 4.561 .077 43.597 100.630
AVER: 21.485 10.743 7.589 11.597 4.867 .077 43.597 99.955
SDEV: .140 .107 .517 .333 .392 .000 .000 .424
SERR: .062 .048 .231 .149 .175 .000 .000
%RSD: .65 1.00 6.81 2.87 8.05 .00 .00
PUBL: 21.199 10.899 7.742 11.657 4.906 .077 43.597 100.077
%VAR: 1.35 -1.43 -1.97 (-.52) (-.79) .00 .00
DIFF: .286 -.156 -.153 (-.06) (-.04) .000 .000
STDS: 162 162 162 160 160 --- ---
So the Fe is off about 2% which is typical EPMA accuracy. The value here for education is that the students can actually see the effects of increasing count time and/or replicate measurements on their own laptop computers. With a bit of "luck" of course! ;)
-
But what about unknown acquisitions when PFE is in demo or simulation mode?
So if one acquires an unknown sample the software will create a random composition as described previously. However, if the unknown sample is the *same name* as a standard already added to the probe run, it will base the physics on that standard composition, as seen here for the NIST K-412 mineral glass:
ELEM: Si Ca Fe Mg Al
TYPE: ANAL ANAL ANAL ANAL ANAL
BGDS: LIN LIN EDS EDS EDS
TIME: 60.00 60.00 64.00 64.00 64.00
BEAM: 30.00 30.00 30.00 30.00 30.00
ELEM: Si Ca Fe Mg Al SUM
21 21.376 10.788 8.220 10.257 5.251 55.893
22 21.171 10.703 7.830 9.829 4.200 53.734
23 21.220 10.716 9.168 9.776 4.973 55.853
AVER: 21.256 10.736 8.406 9.954 4.808 55.160
SDEV: .107 .046 .688 .264 .544 1.235
SERR: .062 .026 .397 .152 .314
%RSD: .50 .43 8.18 2.65 11.32
STDS: 162 162 162 160 160
But now you may ask: why is the total only 55%? Well since this is an unknown sample, the software does not know that there is oxygen present. Because of course because oxygen was not an analyzed element!
So if we then specify oxygen calculated by stoichiometry in the Calculation Options dialog we now get this result:
ELEM: Si Ca Fe Mg Al O
TYPE: ANAL ANAL ANAL ANAL ANAL CALC
BGDS: LIN LIN EDS EDS EDS
TIME: 60.00 60.00 64.00 64.00 64.00 ---
BEAM: 30.00 30.00 30.00 30.00 30.00 ---
ELEM: Si Ca Fe Mg Al O SUM
21 21.216 10.896 8.503 11.568 5.392 43.370 100.946
22 21.100 10.810 8.100 11.076 4.318 41.808 97.212
23 21.073 10.834 9.488 10.939 5.103 42.794 100.232
AVER: 21.129 10.847 8.697 11.194 4.938 42.657 99.463
SDEV: .076 .045 .714 .331 .556 .790 1.982
SERR: .044 .026 .412 .191 .321 .456
%RSD: .36 .41 8.21 2.96 11.26 1.85
STDS: 162 162 162 160 160 ---
Note that the iron statistics are still not wonderful, but the other elements are fine.
-
Ok, so this is a little silly but it could help students learning to do EPMA in simulation mode from their laptops in class before they get on the actual instrument (as we do in our internship program at UofO). First it was noticed that the code wasn't displaying an escape peak when the emission line energy is high enough to cause one, so that is fixed:
(https://probesoftware.com/smf/gallery/395_10_11_18_5_19_41.png)
Next the code was modified to respect the PHA gain value, as the user adjusts it, so here:
(https://probesoftware.com/smf/gallery/395_10_11_18_5_18_25.png)
now gain adjusted down:
(https://probesoftware.com/smf/gallery/395_10_11_18_5_18_44.png)
and now gain adjusted up (too high in fact!):
(https://probesoftware.com/smf/gallery/395_10_11_18_5_19_01.png)
as suggested by a couple of students in Julie's class this quarter.
-
I've been playing around a bit recently with the simulation/teaching mode and I was wondering - as this is a simulation, do we have to run this in real time? Is there a way I could get PfE to simulate wavescans (for example) as fast as the computer will go (whilst still maintaining the counting statistics for example 6s/point)?
I tried having a look around the forums for whether this has been asked before, but I couldn't find an answer.
-
I've been playing around a bit recently with the simulation/teaching mode and I was wondering - as this is a simulation, do we have to run this in real time? Is there a way I could get PfE to simulate wavescans (for example) as fast as the computer will go (whilst still maintaining the counting statistics for example 6s/point)?
I tried having a look around the forums for whether this has been asked before, but I couldn't find an answer.
Hi Jon,
It's an interesting idea but we cannot think of an easy way to do it. But it's worth thinking about some more.
The simulation mode was actually meant to run as realistically as possible for several reasons, one being to teach students how the various options affect acquisition time. This means keeping the photon rate "real" if you know what I mean. One thing you might try is a very high beam current. That might help with the WDS statistics in simulation mode, but the EDS simulation is already constrained by the Monte Carlo electron trajectory rate- which is somewhere around a few nA of beam current for most computers.
For a bit of history, the simulation mode in Probe for EPMA was originally designed for one purpose only and that was so we could develop the acquisition software without having a microprobe available. That is also why there is separate simulation code for the places where the JEOL and Cameca instruments behave differently!
But maybe Sandrin's "method development" application is what you are looking for?
https://probesoftware.com/smf/index.php?topic=743.0
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Hi John,
Sandrin's method development tool is good, but I've been using the simulation mode in Probe for EPMA to 'sense check' some of the crazier ideas and setups I've been having regarding unusual samples (i.e. things that arent available in that database). Also helps to avoid glaring errors in background positioning etc - all things to minimise setup time actually on the probe.
I'd been ramping up the (simulated) beam current and decreasing the count time, but after your suggestion I decided to take it to an extreme and fiddle with the aperture settings in the probewin.ini file to create a new aperture with a high beam current condition: 5kV, >1000nA, focused beam and a 0.1s dwell time over 1000 points results in full simulated WDS of a simulated materials in a couple of minutes - that'll do for me (I'll use the time to grab a coffee ;-) ).
To go with this, I've created a simulated standard database that I have been inputting ideal compositions of materials, digitize the position of the material in PfE and then convert the position to a wavescan and its the closest software that I know of (only?) to realistically simulate WDS. There's plenty of EDS simulation packages, so this fills a gap for me at least.
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I thought I would share some screen snaps of WDS spectrum simulation in PFE for teaching and/or modeling new compositions and analytical situations.
As you may know PFE synthesizes WDS spectra from previously calculated pure element spectra from Penepma 2012 calculations (EDS spectra are simulated "on-the-fly" during the acquisition). These simulated WDS spectra are summed based on the elemental concentrations, with a crude background simulation, and a rough spectrometer efficiency and absorption edge effects thrown in. Not research grade maybe, but good enough for teaching and/or "what-if" situations.
Starting off with a scan of ZnO at the oxygen emission line position (simulated at 15 keV, 30 nA, 6 sec per point and 300 points):
(https://probesoftware.com/smf/gallery/1_04_05_20_12_50_17.png)
Note that you can see a little of several Zn La 2nd order reflections. Here is another scan of the same region but on pure Zn:
(https://probesoftware.com/smf/gallery/1_04_05_20_12_50_37.png)
Now one can see the 2nd order Bragg reflections better. Here's another scan also at the oxygen emission position but on Al2O3:
(https://probesoftware.com/smf/gallery/1_04_05_20_12_50_56.png)
Note the 3rd order Al reflections. And again on Al metal with about 1% oxygen:
(https://probesoftware.com/smf/gallery/1_04_05_20_12_51_14.png)
Now let's switch to the nitrogen emission line position scanning first on TiN:
(https://probesoftware.com/smf/gallery/1_04_05_20_12_51_34.png)
This is why quantifying nitrogen in the presence of titanium is so difficult...
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I'm bumping this topic forward again, because with everything going on nowadays, the idea of running the Probe for EPMA software in "simulation" mode for teaching EPMA is maybe not such a bad idea. Here's what I recently mentioned to a colleague at a small university that doesn't have their own microprobe, but still wants her students to learn EPMA:
"We have found that using the Probe for EPMA software in "simulation" mode gives the students a quite realistic sense of running samples on the instrument. In simulation (or demo) mode one can set up elements, peak spectrometers, run PHAs, check backgrounds using wavescans, acquire standards, analyze them as secondary standards and also acquire standards "as unknowns" by using an unknown sample name that matches a standard currently in the run (otherwise it generates a random composition that totals close to 100%!). WDS and EDS spectra are realistic and contain typical artifacts such as higher order lines, etc.
It's what Julie does for her probe class in the classroom. Of course, once the students are comfortable with the physics theory and software practice, then they normally do get some hours on the instrument. But teaching in the classroom in simulation mode works quite well. After Julie's class, I've seen students come in the lab, and once samples are in the instrument, they just fire up the software and are basically comfortable on their own."
So if you already have the Probe for EPMA software, you might want to consider the idea of running PFE in this "simulation" mode, at least for part of your EPMA classes. Basically every student simply downloads a copy of CalcZAF and Probe for EPMA on their laptop and they can choose JEOL or Cameca simulation mode and then you walk them through the various procedures in the (socially distanced) classroom (or remotely using Zoom or some other social/meeting app).
The simulation mode is not perfect (no satellite peak emissions from double ionized atoms!), but it does a number of interesting stuff, also including interference corrections, MAN, multi-point backgrounds, automation, etc., etc.
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Hi all,
Hope you're all coping with the present "situation".
I was recently chatting with my lab manager Julie Chouinard, and we were discussing the Fall Industrial Internship program:
https://internship.uoregon.edu/
at the UofO CAMCOR facility:
https://camcor.uoregon.edu/
and how student teaching and lab practicals will be handled with regards to the present social distancing rules. We usually have 10-15 students per class, so with the present restrictions on the number of people in classrooms and labs (see attached below), this needs to be re-considered somewhat.
Now, in past years Julie has taken advantage of the simulation mode in Probe for EPMA, to teach the physical theory of EPMA and microanalysis as the students are guided through the software on their laptop computers in class. As the previous posts in this topic show, it is a quite realistic simulation for acquisition, automation and quantification of both WDS and EDS on JEOL and Cameca simulated instruments. Following these 6 to 8 weeks in the classroom, they would normally schedule a session on the actual instrument with myself or Julie for "hands on" learning in the lab.
Now with the social distancing guidelines in place, she has decided to again proceed with classroom instruction, again using the simulation mode of Probe for EPMA, but now with the students logging in using Zoom and running Probe for EPMA also on their own laptops. The only difference is that everyone will be remote except Julie.
For actual instrument time with the students, she will utilize our screen sharing capabilities already present on our EPMA/SEM instruments, which we have utilized in the past for checking on our instrument when we are away from the lab, by initially letting the student into the lab, then watching from her office using these screen sharing apps, including a PTZ camera for "looking over their shoulder" as needed.
If something unforeseen happens she'll be just down the hall in her office and can walk over to help, but at least for most of the time, it can probably all be handled remotely using screen sharing. This seems like a very reasonable plan to me. What's the plan in your lab for student teaching?
For those labs that already have purchased Probe for EPMA, remember that all your students can download a free copy for running in simulation mode, or for re-processing previously acquired data from your instrument.
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We made some small changes to the simulation or "demo" mode of Probe for EPMA. This simulation mode can be utilized for teaching students as discussed in this topic above.
In fact our company has also been utilizing this simulation mode of PFE for remote training sessions when, for national or corporate security reasons, we cannot make a direct network connection to the instrument computer:
https://probesoftware.com/smf/index.php?topic=1297.0
However, one WDS artifact that we never simulated properly are the long tails of emission lines in WDS spectra, which are due to the "polygonization" effects produced during the manufacturing of Bragg crystals:
https://probesoftware.com/smf/index.php?topic=79.msg7818#msg7818
However it is worth the effort to simulate these polygonization tails for teaching/training purposes because these tails produce most of the spectral interferences that are observed in WDS analyses. Here is an example of a *simulated* Si Ka emission line without these polygonization tails:
(https://probesoftware.com/smf/gallery/1_10_08_21_4_05_41.png)
Note that we are missing the typical extended tails as seen here in an empirical measurement, again in the region of the Si Ka emission lines using a TAP crystal:
(https://probesoftware.com/smf/gallery/1_10_08_21_3_45_08.png)
In addition to the main Ka peak, we also see the minor Si Kb peak. But if we zoom in a little on the background we can more easily see these extended tails around the peaks:
(https://probesoftware.com/smf/gallery/1_10_08_21_3_45_31.png)
We also note some satellite emission lines due to doubly ionized Si atoms.
How to simulate these long tails? Well, one idea is to convolve the WDS spectra at a very low resolution (for example, EDS resolution of ~125 eV), then rescale the spectra to a few percent of the original spectra and sum them. If we do that we obtain a simulated spectrum as seen here, again for Si Ka:
(https://probesoftware.com/smf/gallery/1_10_08_21_3_44_25.png)
and zooming in on the simulated spectrum we see this:
(https://probesoftware.com/smf/gallery/1_10_08_21_4_20_01.png)
It's not perfect, but pretty good. Now all we are missing are the satellite emission lines as noted here:
(https://probesoftware.com/smf/gallery/1_10_08_21_4_09_17.png)
Unfortunately the Penepma software which generates these spectra assumes only neutral atoms, so we are out of luck there. But at least now we can better simulate WDS spectral interferences! :)
IMPORTANT: If you would like to be able to simulate these extended WDS tails in PFE demo mode, you should update *both* your Penepma files *and* your Probe for EPMA files, using the Help | Update Probe for EPMA menu in Probe for EPMA. For updating the Penepma files, check the Update Penema Files Only checkbox.
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The purpose of simulating WDS polygonization tail artifacts is simply to create a more realistic looking spectrum with WDS spectral overlaps from the long tails we observe in our instruments. So yesterday I decided to test how well these simulated tails could used to demonstrate the quantitative spectral interference corrections in Probe for EPMA simulations.
But first let me mention that the simulated WDS spectra generated in Probe for EPMA are synthesized by summing pre-calculated Penepma spectra for *pure elements* at various electron beam energies:
https://probesoftware.com/smf/index.php?topic=202.msg9589#msg9589
This is in contrast to the EDS simulated spectra generated in Probe for EPMA which are created by running Penepma in real time based on the actual compositions. My impression is that running Penepma in real time is roughly equivalent to an actual beam current of a few nano-amps. These simulated EDS spectra can then be quantified (when run long enough for sufficient statistics) for any elements in the spectrum.
Unfortunately we cannot do the same for WDS scans because the scan would vary in statistical significance during the simulated scan "acquisition". So we resort to pre-calculated pure element simulations performed at 1 eV intervals for WDS resolution. In addition these WDS spectra for each analyzed element are re-normalized for the element in question to generate a quantitative intensity for that element, but other secondary emission lines in the spectra from other elements cannot be considered quantitative since currently, no absorption correction is applied to the spectra when they are summed. In other words the pure element spectra are quantitative, but not necessarily the compound spectra.
Anywho, I decided to perform a simulation for Ti, V and Cr using pure element standards and a secondary standard of a Ti, Al, V, Cr alloy (SRM 654b) to see just how bad the interference correction is when performed on these simulated spectra with the newly added polygonization artifacts. For reference the composition of SRM 654b is shown here:
St 654 NBS SRM-654b
TakeOff = 40.0 KiloVolt = 15.0 Density = 5.000 Type = alloy
NBS (NIST), Ti base alloy
Elemental Composition
Average Total Oxygen: .000 Average Total Weight%: 100.000
Average Calculated Oxygen: .000 Average Atomic Number: 21.491
Average Excess Oxygen: .000 Average Atomic Weight: 45.783
ELEM: Ti Al V Fe Sn Cu Ni Cr Si Mo Zr
XRAY: ka ka ka ka la ka ka ka ka la la
ELWT: 88.974 6.340 4.310 .230 .023 .004 .028 .025 .045 .013 .008
KFAC: .8825 .0449 .0420 .0021 .0002 .0000 .0003 .0002 .0004 .0001 .0001
ZCOR: 1.0082 1.4110 1.0270 1.0837 .9563 1.0886 1.0434 1.1243 1.2290 1.0746 1.1283
AT% : 85.041 10.758 3.873 .189 .009 .003 .022 .022 .073 .006 .004
First here is the simulated WDS spectra for V Ka (interfered by Ti Kb):
(https://probesoftware.com/smf/gallery/1_13_08_21_2_46_30.png)
Note that the 4 wt% V emission is quite interfered by the 89 wt%Ti (Kb) emission. The Cr Ka emission is also somewhat interfered by the vanadium Kb emission as seen here:
(https://probesoftware.com/smf/gallery/1_13_08_21_2_46_44.png)
An example of what I call a "cascade" interference, where A interferes with B, and B interferes with C, which requires an iterative solution for quantitative results (the situation where two primary analytical emission lines *both* interfere with each other (e.g., Ba La and Ti Ka), I call "self-interfering" or "pathological" interferences, which also requires an iterative solution).
Using instrumental measurements on this same alloy produces excellent results as shown many years ago in this paper (see last line in table 1 on page 26):
https://epmalab.uoregon.edu/publ/Improved%20Interference%20(Micro.%20Anal,%201993).pdf
OK, so first is the simulated "analysis" of the alloy *without* an interference correction:
St 654 Set 1 NBS SRM-654b
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 30.0 Beam Size = 0
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 600, Magnification (imaging) = 200)
Image Shift (X,Y): .00, .00
NBS (NIST), Ti base alloy
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 08/11/2021 09:32:18 AM to 08/11/2021 09:35:22 AM
Average Total Oxygen: .000 Average Total Weight%: 100.360
Average Calculated Oxygen: .000 Average Atomic Number: 21.492
Average Excess Oxygen: .000 Average Atomic Weight: 45.810
Average ZAF Iteration: 2.00 Average Quant Iterate: 2.00
St 654 Set 1 NBS SRM-654b, Results in Elemental Weight Percents
ELEM: Ti V Cr Al Fe
TYPE: ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN LIN
TIME: 20.00 20.00 20.00 --- ---
BEAM: 30.01 30.01 30.01 --- ---
ELEM: Ti V Cr Al Fe SUM
116 89.094 4.914 .089 6.340 .230 100.666
117 88.600 5.037 .108 6.340 .230 100.315
118 88.645 4.936 .100 6.340 .230 100.251
119 88.728 5.012 .076 6.340 .230 100.386
120 88.608 4.952 .052 6.340 .230 100.182
AVER: 88.735 4.970 .085 6.340 .230 100.360
SDEV: .207 .052 .022 .000 .000 .187
SERR: .093 .023 .010 .000 .000
%RSD: .23 1.05 25.80 .00 .00
PUBL: 88.974 4.310 .025 6.340 .230 99.879
%VAR: -.27 15.32 239.36 .00 .00
DIFF: -.239 .660 .060 .000 .000
STDS: 522 523 524 --- ---
STKF: .9940 1.0000 .9988 --- ---
STCT: 344.27 340.70 339.74 --- ---
UNKF: .8805 .0484 .0008 --- ---
UNCT: 304.95 16.49 .26 --- ---
UNBG: .49 .53 .94 --- ---
ZCOR: 1.0078 1.0268 1.1233 --- ---
KRAW: .8858 .0484 .0008 --- ---
PKBG: 627.81 31.97 1.28 --- ---
Note that the V concentration is high by about 0.5 wt% and the Cr is high by about 160 PPM. Now the same analysis but *with* an interference correction applied:
St 654 Set 1 NBS SRM-654b
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 30.0 Beam Size = 0
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 600, Magnification (imaging) = 200)
Image Shift (X,Y): .00, .00
NBS (NIST), Ti base alloy
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 08/11/2021 09:32:18 AM to 08/11/2021 09:35:22 AM
Average Total Oxygen: .000 Average Total Weight%: 99.749
Average Calculated Oxygen: .000 Average Atomic Number: 21.482
Average Excess Oxygen: .000 Average Atomic Weight: 45.781
Average ZAF Iteration: 2.00 Average Quant Iterate: 4.00
St 654 Set 1 NBS SRM-654b, Results in Elemental Weight Percents
ELEM: Ti V Cr Al Fe
TYPE: ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN LIN
TIME: 20.00 20.00 20.00 --- ---
BEAM: 30.01 30.01 30.01 --- ---
ELEM: Ti V Cr Al Fe SUM
116 89.113 4.287 .084 6.340 .230 100.053
117 88.619 4.413 .103 6.340 .230 99.705
118 88.664 4.312 .095 6.340 .230 99.641
119 88.747 4.387 .072 6.340 .230 99.775
120 88.627 4.328 .047 6.340 .230 99.573
AVER: 88.754 4.345 .080 6.340 .230 99.749
SDEV: .207 .053 .022 .000 .000 .186
SERR: .093 .024 .010 .000 .000
%RSD: .23 1.22 27.23 .00 .00
PUBL: 88.974 4.310 .025 6.340 .230 99.879
%VAR: -.25 .82 221.58 .00 .00
DIFF: -.220 .035 .055 .000 .000
STDS: 522 523 524 --- ---
STKF: .9940 1.0000 .9988 --- ---
STCT: 344.27 340.70 339.74 --- ---
UNKF: .8805 .0423 .0007 --- ---
UNCT: 304.95 14.42 .24 --- ---
UNBG: .49 .53 .94 --- ---
ZCOR: 1.0080 1.0270 1.1242 --- ---
KRAW: .8858 .0423 .0007 --- ---
PKBG: 627.81 28.07 1.26 --- ---
INT%: ---- -12.59 -5.68 --- ---
Now with the interference applied the V concentration is quite good, but the Cr concentration is under corrected and still a bit high. I'm going to say that this first attempt at adding WDS polygonization artifacts in these simulated WDS spectra is pretty good, but not quite quantitative enough at the 1000 PPM level and below. I will continue to evaluate and let you all know what else I find.
In summary I would say these polygonization simulations are good enough for teaching and training, which of course is the whole purpose of the simulation mode in Probe for EPMA. Please feel free to try some WDS simulations of your own, and share your results here in this topic.
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It is worth mentioning that one can simulate time dependent intensity (TDI) effects in Probe for EPMA for teaching microprobe techniques. However, there are a few caveats:
1. First one needs to turn off the Penepma simulation mode for the TDI simulation using the checkbox as shown here:
(https://probesoftware.com/smf/gallery/1_21_08_21_9_31_51.png)
Note also the "tooltip" pop up help that mentions this. The only downside of turning off the Penepma simulation is that wavescans will only contain a single peak for the specified emission line, but since the Penepma simulation can be turned off for (TDI) unknowns and/or standards and turned on for wavescans, this shouldn't be a problem.
2. So once the Penepma simulation is turned off and the TDI acquisition is turned on in the Special Options dialog, the first element in the acquisition will always utilize a "Na" type log-linear intensity decay, while the second element will always utilize a "Si" smaller log-linear increase in intensity as one would normally observe in an alkali glass specimen.
Therefore to simulate TDI effects when teaching EPMA please realize that these TDI effects will only be generated when Penepma simulations are turned off in the Acquisition Options dialog and "self" TDI acquisitions are selected in the Special Options dialog, both accessed from the Acquire! window.
Then you will be able to display simulated TDI intensities as shown here for the first element "Na":
(https://probesoftware.com/smf/gallery/1_21_08_21_9_32_12.png)
And perform quantitative analyses of these "beam sensitive" materials for teaching in simulation or demonstration mode:
Un 6 Obsidian CAMM 112, Results in Elemental Weight Percents
ELEM: Na Si Ti Al Fe Mg Mn P Ca K H O
TYPE: ANAL ANAL SPEC SPEC SPEC SPEC SPEC SPEC SPEC SPEC SPEC SPEC
BGDS: LIN LIN
TIME: 10.00 10.00 --- --- --- --- --- --- --- --- --- ---
BEAM: 30.01 30.01 --- --- --- --- --- --- --- --- --- ---
ELEM: Na Si Ti Al Fe Mg Mn P Ca K H O SUM
34 3.044 33.456 .060 6.563 .909 .018 .015 .003 .322 3.761 .086 49.326 97.563
35 2.837 33.586 .060 6.563 .909 .018 .015 .003 .322 3.761 .086 49.326 97.486
36 3.127 33.961 .060 6.563 .909 .018 .015 .003 .322 3.761 .086 49.326 98.151
37 3.151 33.766 .060 6.563 .909 .018 .015 .003 .322 3.761 .086 49.326 97.980
AVER: 3.040 33.692 .060 6.563 .909 .018 .015 .003 .322 3.761 .086 49.326 97.795
SDEV: .143 .220 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .322
SERR: .071 .110 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
%RSD: 4.70 .65 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
STDS: 336 14 --- --- --- --- --- --- --- --- --- ---
STKF: .0735 .4101 --- --- --- --- --- --- --- --- --- ---
STCT: 26.25 144.09 --- --- --- --- --- --- --- --- --- ---
UNKF: .0165 .2764 --- --- --- --- --- --- --- --- --- ---
UNCT: 5.90 97.12 --- --- --- --- --- --- --- --- --- ---
UNBG: .42 .86 --- --- --- --- --- --- --- --- --- ---
ZCOR: 1.8380 1.2188 --- --- --- --- --- --- --- --- --- ---
KRAW: .2249 .6741 --- --- --- --- --- --- --- --- --- ---
PKBG: 15.05 114.76 --- --- --- --- --- --- --- --- --- ---
TDI%: 10.394 -2.482 --- --- --- --- --- --- --- --- --- ---
DEV%: 1.5 .2 --- --- --- --- --- --- --- --- --- ---
TDIF: LOG-LIN LOG-LIN --- --- --- --- --- --- --- --- --- ---
TDIT: 13.00 13.00 --- --- --- --- --- --- --- --- --- ---
TDII: 6.36 97.9 --- --- --- --- --- --- --- --- --- ---
TDIL: 1.85 4.58 --- --- --- --- --- --- --- --- --- ---
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And finally another "tweak" to improve the simulation mode in Probe for EPMA: we modified the background curvature model to produce background intensities (as a function of sin theta) for LDE/PC Bragg multi-layer crystals that more closely resemble what we actually observe on the actual instrument:
(https://probesoftware.com/smf/gallery/1_22_08_21_9_23_47.png)
This allows one to model curved backgrounds more easily in simulation mode. Update PFE as usual to obtain this improved wavescan simulation for teaching and training off-line.
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Just in case anyone didn't know, one can perform WDS simulations in Probe for EPMA using 30 keV beam energies. Basically we finally finished modeling all the elements up to 30 keV using 1 eV energy bins using Penepma.
(https://probesoftware.com/smf/gallery/1_09_11_21_10_20_25.png)
To update your Penepma pure element databases, use the Help | Update button as described here:
https://probesoftware.com/smf/index.php?topic=202.msg9589#msg9589
Being sure to check the Update Penepma Monte-Carlo Files Only checkbox.