Author Topic: New Features In Probe for EPMA  (Read 51023 times)

John Donovan

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Re: New Features In Probe for EPMA
« Reply #135 on: May 08, 2020, 12:06:39 pm »
Along with the distribution, we've also updated the distribution to include these Li, Be and B emissions. This is to allow Probe for EPMA to simulate WDS spectra containing these elements in "demo" mode for teaching EPMA and other "off-line" WDS modeling needs.

To perform these WDS simulations in Probe for EPMA, you should update Probe for EPMA using the Help menu as usual, to v. 12.8.6. After Probe for EPMA is updated, use the same update dialog again, but this time check the box "Update Penepma Monte Carlo Files Only", and download the update again.  The updated Penepma files will be automatically unzipped.

Once that is done you can create WDS spectra simulations such as this for pure Be metal (after properly peaking the "simulated" spectrometer of course!):

Note that on this PC2.5 LDE the Be Ka emission line is quite close to the spectrometer limit, but it might be doable though I don't have any experimental data to compare it with. And this for Beryl (Be3Al2Si6O18) which has about 5 wt% Be:

Note that in the beryl simulation you can see the approach of higher order oxygen lines to the left of the Be Ka emission.

As a slight aside, the discerning eye may notice that sometimes the red line showing the peak center does not line up exactly with the KLM markers line (in brown). This is more easily seen in this scan of boron Ka in boron nitride (BN) which also contains some carbon and oxygen:

One will also notice that the carbon Ka and O Ka II KLM markers are also off from their peak positions. Why is this you may ask?

Well it's simply due to the fact that we utilize the Armstrong x-ray database from Cal Tech for the actual peak positions (and quantification), but we utilize the NIST x-ray database for the KLM markers, and unfortunately they don't always agree exactly.  In fact the Cal Tech table has B Ka at 0.1834 keV, while the NIST table has it at 0.185 keV. This plot in keV space makes this offset quite clear:

These database discrepancies are usually seen for the light element emission lines, and since these line positions are very subject to chemical state shifts, we don't think one should worry too much about it.  However, if it really bothers anyone, you can edit the emission (and edge) energies that Probe for EPMA (and CalcZAF) utilize by following these instructions:
John J. Donovan, Pres. 
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