Questions about MAN background use

[AndrewLocock]

[If someone has a ASCII table with these Auger lines feel free to post it.  We would like to have at least the text labels, energies and nominal intensities for each emission line.

The Coghlan and Clausing 1973 reference is: Atomic Data and Nuclear Data Tables, volume 5, issue 4, pp. 317-469, and may be found at
https://doi.org/10.1016/S0092-640X(73)80005-1

More recent progress in simulation and calculation of electron spectra and Auger kinetic energies are given by:

Smekal, W., Werner, W.S. and Powell, C.J., 2005. Simulation of electron spectra for surface analysis (SESSA): a novel software tool for quantitative Auger‐electron spectroscopy and X‐ray photoelectron spectroscopy. Surface and Interface Analysis: An International Journal devoted to the development and application of techniques for the analysis of surfaces, interfaces and thin films, 37(11), pp.1059-1067.

Werner, W.S., Smekal, W. and Powell, C.J., 2011. NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA). In Version 1.3, Standard Reference Program Database 100, US Department of Commerce. National Institute of Standards and Technology Gaithersburg, MD.

Dean, J.W., Chantler, C.T. and Ganly, B., 2022. Ab initio calculations of Auger electron kinetic energies: Breadth and depth. Radiation Physics and Chemistry, 200, p.110472.

Unfortunately, the online NIST X-ray Photoelectron Spectroscopy Database is not comprehensive:
https://srdata.nist.gov/xps/Default.aspx

[John Donovan]

I also calculated data for MAN BG curve. It is a bit different topic but could you explain how I can download the calculated MAN BG to PFE.

The mean atomic number (MAN) background correction curve is not a static fit. It is a dynamic fit based on the current selection of standards available and/or selected by the user and also corrected for standard intensity drift in real time and of course the current standard compositions. Also to a very small degree, the current dead time constants and equations.

In addition it is affected by the choice of the model for the calculation of average Z.  Traditionally we have utilized a mass fraction model, but we now know (publication coming soon), that mass has nothing to do with continuum production and so one should generally select the Z Fraction model which is based on the number of atoms and their atomic numbers which scales roughly as Z^2/3.  There is a topic here that explains this:

https://smf.probesoftware.com/index.php?topic=1221.msg10187#msg10187

To answer your question though, one can only import the standard intensities utilized in the MAN fit from another Probe for EPMA probe run. This can be done at any time whenever the Load File Setup button is selected from the Acquire! window New Sample/Setup button and the user clicks Yes to the question: Do you want to load the standard intensities?  after the sample setup has been loaded.

[John Donovan]

Here is the new Z fraction average Z calculation using a fixed exponent as described in our recent paper this summer:

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



Here the Z fraction exponent is fixed at 0.7 for all MAN elements.  However, starting with v. 13.4.4 of Probe for EPMA you can now change this exponent to a zero and the program will automatically calculate the optimized exponent based on the emission line energy (as described in the paper linked above).

Here we've entered a zero for the Z fraction exponent and clicked the Update Fits button. We can can now see the calculated "optimized" Z bar exponent is 0.67 which produces a better Rel % Deviation fit to the MAN standards:

[John Donovan]

Note that if you have these two options checked in the Analytical | Analysis Options menu dialog:



you will see the MAN fit details for the optimized Z fraction exponent, "ZEXP:" parameter:

St  310 Set   2 SM Fayalite, Results in Elemental Weight Percents

ELEM:       Si      Al      Ca       K      Ti      Cr      Fe      Mn
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL
BGDS:      MAN     MAN     MAN     MAN     MAN     MAN     MAN     MAN
MAN1:  .165963 2.59049 -.08976 -.10492 -.36600 -1.2218 -.18728 .109394
MAN2:  .196322 -.22066 .068148 .119022 .255554 .312196 .102628 .039946
MAN3:  .000000 .012323 .000000 -.00014 .000000 -.00291 .000000 .001477
ABS%:   -27.70  -39.15   -3.56   -5.55   -1.30    -.28     .18     .00
ZEXP:      .64     .63     .69     .68     .70     .72     .73     .73
TIME:    40.00   40.00   40.00   20.00   20.00   40.00   25.00   25.00
BEAM:    19.97   19.97   19.97   19.97   19.97   19.97   19.97   19.97

Assuming the MAN Z Fraction exponent is set to zero...

[AndrewLocock]

Here is the new Z fraction average Z calculation using a fixed exponent as described in our recent paper this summer:

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



Here the Z fraction exponent is fixed at 0.7 for all MAN elements.  However, starting with v. 13.4.4 of Probe for EPMA you can now change this exponent to a zero and the program will automatically calculate the optimized exponent based on the emission line energy (as described in the paper linked above).

Here we've entered a zero for the Z fraction exponent and clicked the Update Fits button. We can can now see the calculated "optimized" Z bar exponent is 0.67 which produces a better Rel % Deviation fit to the MAN standards:

A related request - can you arrange for Probe-for-EPMA to export the graphic of the MAN assignment and fit for each X-ray line used?
At present, I use the Windows Snip tool and dump the graphic into Word (see attached).
In this way, I can the reference materials used (or most of them), the Rel% Deviation, the Curvature, the Slope and Intercept, as well as the Z-bar Exponent.

Further question - what are acceptable values or ranges in the MAN fit for: the Rel% Deviation, the Curvature, the Slope and Intercept?
At present, I like to have Rel% Deviation certainly less than 3, preferably less than 2.
I like to have the Intercept close to zero (not always possible, unclear as to why).
What do others find acceptable?

Thanks,
Andrew

[John Donovan]

A related request - can you arrange for Probe-for-EPMA to export the graphic of the MAN assignment and fit for each X-ray line used?
At present, I use the Windows Snip tool and dump the graphic into Word (see attached).
In this way, I can the reference materials used (or most of them), the Rel% Deviation, the Curvature, the Slope and Intercept, as well as the Z-bar Exponent.

If you click the Print Additional MAN Fit and Correction Parameters checkbox as described here:

https://smf.probesoftware.com/index.php?topic=4.msg12053#msg12053

much if not all of this info is output to the log window.

Further question - what are acceptable values or ranges in the MAN fit for: the Rel% Deviation, the Curvature, the Slope and Intercept?
At present, I like to have Rel% Deviation certainly less than 3, preferably less than 2.
I like to have the Intercept close to zero (not always possible, unclear as to why).
What do others find acceptable?

The MAN fits in your Word document in the post above look really good to me.  I guess it just depends on the sensitivity/accuracy you require.  The 2016 MAN paper goes into this in some detail:

https://epmalab.uoregon.edu/publ/A%20new%20EPMA%20method%20for%20fast%20trace%20element%20analysis%20in%20simple%20matrices.pdf

[John Donovan]

A related request - can you arrange for Probe-for-EPMA to export the graphic of the MAN assignment and fit for each X-ray line used?
At present, I use the Windows Snip tool and dump the graphic into Word (see attached).

Note that you can also use the <alt> <Print Screen> key combo to capture just the current window to the system clipboard.

We could also add a "Clipboard" button to the MAN dialog.

[John Donovan]

The latest version of Probe for EPMA v. 13.5.9 now includes a Clipboard button in the MAN window and also outputs the MAN coefficients and relative % deviations (and exponents if utilizing the Z Fraction MAN fit option) if using the Print MAN Fit and Correction Parameters to Log Window (and Use Detailed Output) option from the Analytical | Analysis Options dialog which can be see here for mass fraction MAN Z bar calculation:

St  358 Set   2 Diopside (Chesterman), Results in Elemental Weight Percents

ELEM:       Na      Si       K      Al      Mg      Fe      Ca      Mn       O       H
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    SPEC    SPEC
BGDS:      MAN     MAN     LIN     MAN     MAN     MAN     MAN     LIN
MAN1:  8.21064 17.6972         15.1856 -23.560 3.60143 4.96464                       
MAN2:  .298724 .235361         1.31971 5.10899 .135131 2.51710                       
MAN3:  .039522 .000000         .016978 -.09491 .014340 .018263                       
REDV:     5.88   11.90             .77    3.37     .93    1.89                       
ABS%:   -45.67  -17.88          -27.57  -30.56    -.79   -2.99                           

And here for Z fraction MAN Z bar calculation (constant exponent) with the constant exponent:

St  358 Set   2 Diopside (Chesterman), Results in Elemental Weight Percents

ELEM:       Na      Si       K      Al      Mg      Fe      Ca      Mn       O       H
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    SPEC    SPEC
BGDS:      MAN     MAN     LIN     MAN     MAN     MAN     MAN     LIN
MAN1:  4.05116 17.6299         15.3465 -30.781 1.65561 -2.6997                       
MAN2:  .850560 .251887         1.24988 6.25317 .366658 3.66492                       
MAN3:  .028771 .000000         .025809 -.12994 .010452 -.00973                       
REDV:     7.10   11.91            1.88    1.81     .22    4.33                       
ABS%:   -45.67  -17.88          -27.57  -30.56    -.79   -2.99                       
ZEXP:      .70     .70             .70     .70     .70     .70                           

And here for Z fraction MAN Z bar calculation (variable exponent):

St  358 Set   2 Diopside (Chesterman), Results in Elemental Weight Percents

ELEM:       Na      Si       K      Al      Mg      Fe      Ca      Mn       O       H
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    SPEC    SPEC
BGDS:      MAN     MAN     LIN     MAN     MAN     MAN     MAN     LIN
MAN1:  2.00334 17.6443         14.9056 -32.456 1.84603 -3.2513                       
MAN2:  1.13292 .253212         1.30209 6.52835 .344140 3.74527                       
MAN3:  .021317 .000000         .025652 -.13876 .010783 -.01194                       
REDV:     7.63   11.92            2.34    1.50     .16    4.45                       
ABS%:   -45.67  -17.88          -27.57  -30.56    -.79   -2.99                       
ZEXP:      .62     .64             .63     .63     .73     .69                         

[John Donovan]

We also modified the Report output table format to include MAN statistics as requested by Andrew Locock:

[John Donovan]

Ben Buse found a bug in the MAN Z Fraction option that is now fixed in the latest version of Probe for EPMA v. 14.1.8. The details are worth reporting.

Apparently when we introduced the Z fraction method for calculating the Donovan and Moy (DAM) backscatter method back in 2023, we accidentally broke the Z fraction calculation for the MAN fit. The previous code was only calculating the Z fraction average atomic number for the DAM backscatter correction and no longer for the MAN Z fraction method. The new code now calculates the Z fraction atomic weight for both the DAM BSC matrix correction and the MAN Z fraction method. Thanks to Ben Buse's keen eyes, this is fixed now!

The MAN display was still working fine, just the analysis wasn't using the Z fraction average atomic number calculation.  This bug only has a significant effect for high Z materials where one was using the MAN correction for analyzing materials that contain elements with quite different A/Z ratios, e.g., ThSiO4, UO2, etc.  For example here is the MAN fit for Th Ma using mass fractions for a monazite run from Karsten Goemann:



Note that std 234 (GaAs) has a mass fraction average Z of around 32 and note also it's location in X compared to the other standards shown.  Now when we switch to the Z fraction method we get this plot:



We can see that the GaAs std hasn't moved in X (average Z), but many of the other standards have shifted in average atomic number! That's because these other standards contain elements that have different A/Z ratios. This is because the elements Ga and As have every similar A/Z ratios as seen here:



So no matter what method you use to calculate the average atomic number for GaAs you're going to get something around 32. However, for a material such as uranium oxide (UO2) the difference is much larger:



So, let's test this with the updated PFE software, starting with analyzing a UO2 std using the mass fraction average Z calculation:



If you look at the Th Ma results you can see we are getting an average of around 200 PPM, though it's not statistically significant. In any case, switching to the Z fraction method, we now get an average even closer to zero:



Ben was seeing a somewhat larger difference in his analyses, so hopefully he will chime in after he updates his software using the Help menu as usual, or downloading from our Resources page:

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

I just realized a better example is to show the shift in the GaAs std because Karsten utilized a number of standards containing elements with different A/Z ratios. Using an MAN fit with mass fractions we get this:

ELEM:       Th      Si       U      Pb      Pb       P      Al 
XRAY:     (ma)    (ka)    (mb)    (mb)    (mb)    (ka)    (ka) 
    96  .08626  .02054  .10886  .08703  .00000  .00594  .10038 
    97  .04363  .02124  .10805  .10889  .00000 -.00006  .07247 
    98  .05993  .01863  .09308  .08384  .00000  .00248  .07150 
    99  .06832  .02588  .13177  .08239  .00000  .00489  .05488 
   100  .05900  .01903  .11724  .11018  .00000 -.00170  .04452 

AVER:   .06343  .02106  .11180  .09447  .00000  .00231  .06875 
SDEV:   .01556  .00290  .01416  .01386  .00000  .00322  .02122 
SERR:   .00696  .00130  .00633  .00620  .00000  .00144  .00949 
%RSD:  24.5352 13.7528 12.6614 14.6758   .0000 139.514 30.8629 

And using Z fraction we get this:

ELEM:       Th      Si       U      Pb      Pb       P      Al 
XRAY:     (ma)    (ka)    (mb)    (mb)    (mb)    (ka)    (ka) 
    96  .02118  .00367  .00850  .01625  .00000  .00185  .09159 
    97 -.02151  .00435  .00731  .03811  .00000 -.00415  .06356 
    98 -.00519  .00174 -.00748  .01314  .00000 -.00161  .06259 
    99  .00319  .00900  .03126  .01177  .00000  .00080  .04590 
   100 -.00609  .00215  .01672  .03954  .00000 -.00579  .03550 

AVER:  -.00168  .00418  .01126  .02376  .00000 -.00178  .05983 
SDEV:   .01558  .00290  .01418  .01385  .00000  .00322  .02131 
SERR:   .00697  .00130  .00634  .00620  .00000  .00144  .00953 
%RSD:  -925.38 69.2505 125.898 58.3062   .0000 -181.09 35.6179 

So you can see that almost all the analytical elements improved their zero accuracy even at high Z.

[Ben Buse]

Just to add it's impressive how well the z-frac works for high MAN materials, shifting the z considerably.

Here's showing a range of oxides and metals without z-frac - black line highlighting the oxide standards


Here's just metals without z-frac


And here's with the z-frac, which does a very good job for the oxide and metals together

[John Donovan]

One of our colleagues was using MAN background corrected elements, but he was adding and removing elements changing spectrometers, adding standards, what have you...  after having run some standards for some elements and assigned the MAN fits.  He wrote me his rough sequence of events:

Create routine including 6 elements with MAN backgrounds and 6 elements with off-peak backgrounds. PHA and peak each individually.
    Run a manual version of quick standards, where I enable acquisition of only the primary element for that standard and the 6 MAN elements. Run these one at a time. All off-peak elements are now calibrated.
    After running the first set of standards with mixed MAN and off-peak, user decides they want to re-arrange some elements (remove one of the off-peak elements (O) and switch spec 4 from PC0 crystal to PET, to move two of the MAN elements to PET (K and Ca)).
    After switching these two elements, I adjust PHA and peaked both of them individually. Then ran a large batch of MAN standards, this time with all of the off-peak elements disabled.
    After running the MAN standards, I assign MAN fits, which all look normal.
    When I run a test measurement, I get an error that there is no data for one of the MAN elements (Na). This error only seems to affect some of the MAN elements and not others, and not necessarily the ones that switched spectrometers. I ran several tests with just one element enabled at a time to confirm that the error appears for some MAN elements and not others. For example, I get the error for the first element on spec 1 (Na) but not the second element (Mg)

So, yeah, a bit complicated.

Anyway, after doing all this he wanted to go back into the MAN assignments menu dialog and check everything, but he got this warning message:



Note that I highlighted the Update Fit button suggestion. One can continue and see each standard that is missing for each MAN element as seen here:



But, the best procedure is as follows:

1. Cancel back to the main Probe for EPMA dialog.

2. Click the Clear All MAN Assignments menu. This will force the program to search for all MAN elements in all the standards.

3. Again click the Assign MAN Fits menu and skip the warnings and open the dialog as seen here:



I've highlighted the Update Fit button because that mostly takes care of these issues, when a standard used in the MAN fits wasn't run with all the elements. That is, the software will only select the standards that it found MAN data for that element.  But it won't update the MAN assignments until you click the Update Fit button.

4. So click on each element in the list, check the MAN intensities for high outliers (e.g., interferences or trace contamination), and unselect any standards that are problematic.

5. Click the Update Fit button and repeat for each element in the list

6. Click OK and exit the dialog.

You should be good to go now.  You might also want to check our YouTube videos on using MAN backgrounds corrections:

https://www.youtube.com/@ProbeSoftware

[John Donovan]

We've improved the warning message when someone has not acquired all the standards for an element using MAN backgrounds:



Note that you don't have to acquire these missing standards for that element if you don't want to (though you certainly can).  But you will need to confirm the MAN assignments by clicking the Update Fit button for ALL elements that are missing MAN standards: