Latest version changes for Probe for EPMA (and CalcImage) v. 14.3.8

[John Donovan]

The latest v. 14.3.6 of Probe for EPMA now includes a pdf document accessed from the Help menu, which explains our very unintuitive method for PHA tuning for high accuracy microanalysis.  Even when extrapolating from pure metals or pure oxides to alloys/sulfides or oxides/silicates, respectively.



Of course this also requires that one has properly calibrated their dead time constants (and using the logarithmic dead time equation in Probe for EPMA), because we are no longer "count rate matching" our standard to our unknown.

And of course for large atomic number extrapolations, we require the Donovan and Moy Z based backscatter correction as described here by Andrew Locock:

https://smf.probesoftware.com/index.php?topic=40.msg13051#msg13051

See also here for many examples of ~1% or better relative accuracy in most of these "Xtreme" extrapolations:

https://smf.probesoftware.com/index.php?topic=1831.0

All of this assumes that your WDS spectrometers are mechanically aligned, which can be chcked using the Bragg order k-ratio test:

https://smf.probesoftware.com/index.php?topic=1739.0

[John Donovan]

Here's something new.

We added a new field in the manual PHA tuning window as seen here:



By default it loads the current sample (as displayed in the list), but you can edit this field to change the text to maybe the sample you're actually on, or perhaps to other comments. This material name and/or comments are now displayed in the Run | Display, Fit and Export Spectrometer and PHA scans menu dialog as seen here:



This field was previously only utilized when performing peaking/PHA acquisitions from the Automate! window, but now one can add comments to this field when manually tuning the PHAs.

Update Probe for EPMA from the Help menu as usual.

[John Donovan]

Here's a new feature in the Output | Output Standard and Unknown XY Plots menu:



If you have the Standards option selected for the sample list there are now three new entries for each analyzed element: published values, percent variances and algebraic differences. These are the same parameters seen in the log window output:

St  162 Set  12 NBS K-411 mineral glass, Results in Elemental Weight Percents
 
ELEM:       Ti      Fe      Sr      Rb      Mn      Cr      Si      Mg      Ca      Al       O
TYPE:     ANAL    ANAL    SPEC    SPEC    SPEC    SPEC    SPEC    SPEC    SPEC    SPEC    SPEC
BGDS:      LIN     LIN
TIME:    60.00   60.00     ---     ---     ---     ---     ---     ---     ---     ---     ---
BEAM:    19.94   19.94     ---     ---     ---     ---     ---     ---     ---     ---     ---

ELEM:       Ti      Fe      Sr      Rb      Mn      Cr      Si      Mg      Ca      Al       O   SUM  
  1175    .003  11.156    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.133
  1176    .003  11.146    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.123
  1177    .005  11.160    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.139
  1178    .002  11.177    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.153
  1179    .001  11.157    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.131
  1180   -.002  11.122    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.094

AVER:     .002  11.153    .000    .000    .077    .000  25.382   8.847  11.057    .053  43.558 100.129
SDEV:     .002    .018    .000    .000    .000    .000    .000    .000    .000    .000    .000    .020
SERR:     .001    .007    .000    .000    .000    .000    .000    .000    .000    .000    .000
%RSD:   108.44     .16     .00     .00     .00     .00     .00     .00     .00     .00     .00

PUBL:     n.a.  11.209    n.a.    n.a.    .077    n.a.  25.382   8.847  11.057    .053  43.558 100.183
%VAR:      ---    -.50     ---     ---     ---     ---     ---     ---     ---     ---     ---
DIFF:      ---   -.056     ---     ---     ---     ---     ---     ---     ---     ---     ---
STDS:       22     395     ---     ---     ---     ---     ---     ---     ---     ---     ---

STKF:    .5626   .6867     ---     ---     ---     ---     ---     ---     ---     ---     ---
STCT:  1833.94 1035.28     ---     ---     ---     ---     ---     ---     ---     ---     ---

UNKF:    .0000   .0965     ---     ---     ---     ---     ---     ---     ---     ---     ---
UNCT:      .05  145.51     ---     ---     ---     ---     ---     ---     ---     ---     ---
UNBG:     2.68    1.50     ---     ---     ---     ---     ---     ---     ---     ---     ---

ZCOR:   1.1794  1.1556     ---     ---     ---     ---     ---     ---     ---     ---     ---
KRAW:    .0000   .1405     ---     ---     ---     ---     ---     ---     ---     ---     ---
PKBG:     1.02   98.03     ---     ---     ---     ---     ---     ---     ---     ---     ---

Now we can make plots like this:



Note the chromite is a natural sample of uncertain composition.  And also this with a different x axis:

[John Donovan]

Last week Paul Carpenter had another great idea. He requested an extended version of an existing feature, where one can specify the oxygen by stoichiometry and formula basis for ones standard materials in the Standard compositional database. Then these optional parameters can be utilized in Probe for EPMA whenever a new standard sample is created.

This was accomplished using these keywords in the Probewin.ini file:



and first posted about to the forum back in 2018:

https://smf.probesoftware.com/index.php?topic=40.msg7004#msg7004

Now Paul requested that the same feature be implemented for mineral end member assignments. So here is the new standard database dialog for specify the mineral end member for standards in the standard database:



This is now available in v. 14.3.7 of Probe for EPMA. Update as usual from the Help menu or the Probe Software Resource web page.

Note that you must first specify a formula basis for this feature, just as you do in Probe for EPMA. Once you've done that, select the mineral end member option and you will obtain an end member output:



To utilize these end member options when creating new standard samples in Probe for EPMA, use this new keyword in the [standards] section of the probewin.ini file:



Once this keyword is set, every time you create a new sample (manually or automated), Probe for EPMA will automatically load the end member option for that standard:

[John Donovan]

Some of you may know that since its earliest days, Probe for EPMA has offered the MAN background correction method as an alternative to the off-peak background method:

https://smf.probesoftware.com/index.php?topic=1378.0
https://smf.probesoftware.com/index.php?topic=4.0
https://smf.probesoftware.com/index.php?topic=307.0
https://smf.probesoftware.com/index.php?topic=684.0

The original paper on the MAN method from 1996 is here:

https://epmalab.uoregon.edu/publ/Improved%20MAN%20(Jour.%20Micros.%20Microa.,%201996).pdf

And a more recent (2016) paper looking at the statistics of the MAN method for trace element analysis is here:

https://www.probesoftware.com/wp-content/uploads/2024/08/a-new-epma-method-for-fast-trace-element-analysis-in-simple-matrices_opt.pdf

Anyway, geologists seem to like this method, though it can be used with success on many materials. In any case one obtains the same or better precision in half the time! Especially nice for quantitative mapping. And when combined with the blank correction, one can attain trace accuracy equal to ones precision.

One improvement in recent years is the use of the Z Fraction method for calculating average atomic number (Zbar), which is the heart of the MAN method:



Because it turns out that mass fraction is only a proxy for continuum production in compounds:

https://smf.probesoftware.com/index.php?topic=4.msg13411#msg13411

This new Zbar calculation method for continuum (and backscatter) production is published here:

https://academic.oup.com/mam/article-abstract/29/4/1436/7224307

Now, because the Z fraction method is so much more accurate than mass fraction, it has been requested that we therefore make the Z fraction the default method in Probe for EPMA for the MAN correction and we have done this.  Please note this change will not affect data calculated in previous runs (though it would improve accuracy!). However, new probe runs will automatically utilize the Z Fraction method for MAN fits through these new parameters in the Probewin.ini file:



This will occur when you update to the latest Probe for EPMA using the Help menu or Probe Software resources web page...

But if you want to stay with the mass fraction Zbar for MAN calculations (why?), you can edit these parameters in your Probewin.ini.  Just set the UseZFractionZbarCalculationsFlag keyword to 0 in the [software] section of your Probewin.ini file.

While making this change we also improved the output of additional MAN parameters, through this already existing option in the Analytical | Analysis Option menu dialog:



For example, when this box is checked the MAN calculated Zbar is now output as seen here:



And if one utilizes the Z fraction zero exponent which optimizes the MAN fit based on continuum energy, one now obtains this additional output:



Enjoy!