Author Topic: Reed Fluorescence Correction (Improved)  (Read 5851 times)

Probeman

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    • John Donovan
Reed Fluorescence Correction (Improved)
« on: May 06, 2015, 04:27:43 pm »
I've been working on improving the Reed fluorescence correction to include fluorescence by beta lines (and also fluorescence of beta lines, if one really insists on using them as one's analytical line!), but there is not much data to use as a "test bed". 

The Pouchou data set is limited by the fact that the binary compositions selected were chosen to exclude as much as possible large fluorescence correction situations!  The idea being to test the Z and A parts of the analytical expressions.

I've run some Penfluor/Fanal simulations and created a subset of large fluorescence corrections based on that output and that helps. I will be making more rigorous simulations based on the full Penepma but that will take some additional time.

In the meantime there is improvement evident for some 1500 binary compositional situations with large fluorescence corrections.  First the original Reed fluorescence analytical correction:



and here is the same data calculated with the Reed fluorescence correction modified to include beta lines :



Significant improvement though it could be better and I will continue to improve the relative line weight calculations. And don't forget, this is for worst case fluorescence situations, not normal samples.
« Last Edit: August 03, 2015, 01:29:57 pm by John Donovan »
The only stupid question is the one not asked!

Probeman

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Re: Reed Fluorescence Correction (Improved)
« Reply #1 on: May 23, 2015, 04:31:53 pm »
Well I have to admit this hurts a little.

After all that work on improving the Reed fluorescence to include fluorescence *by* beta lines, it sure doesn't have much of an effect for monazite compositions- which I guess is just as well.

Correction Method and Mass Absorption Coefficient File:
ZAF or Phi-Rho-Z Calculations
LINEMU   Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV

Current ZAF or Phi-Rho-Z Selection:
Armstrong/Love Scott (default)

Correction Selections:
Phi(pz) Absorption of Armstrong/Packwood-Brown 1981 MAS
Stopping Power of Love-Scott
Backscatter Coefficient of Love-Scott
Backscatter of Love-Scott
Mean Ionization of Berger-Seltzer
Phi(pz) Equation of Love-Scott
Reed/JTA w/ M-Line Correction and JTA Intensity Mod.
Fluorescence by Beta Lines Included

Un   13 Montel Madagascar 6-1
TakeOff = 40.0  KiloVolt = 20.0  Beam Current = 150.  Beam Size =    5
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =        0, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00
Number of Data Lines:   3             Number of 'Good' Data Lines:   3
First/Last Date-Time: 09/10/2003 10:26:45 AM to 09/10/2003 11:00:49 AM

Average Total Oxygen:       26.248     Average Total Weight%:   99.895
Average Calculated Oxygen:  26.248     Average Atomic Number:   43.366
Average Excess Oxygen:        .000     Average Atomic Weight:   40.599
Average ZAF Iteration:        4.00     Average Quant Iterate:     4.00

Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction

Un   13 Montel Madagascar 6-1, Results in Elemental Weight Percents
 
ELEM:       Ca      Si      Al       Y      Pr      Nd      Sm      Gd      Ce      La       P       U      Pb      Th      Dy      Er       O
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    CALC
BGDS:      LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN
TIME:    40.00   40.00   40.00   40.00   40.00   40.00   40.00   40.00   20.00   20.00   20.00  240.00  240.00  240.00   80.00   80.00     ---
BEAM:   149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54     ---

ELEM:       Ca      Si      Al       Y      Pr      Nd      Sm      Gd      Ce      La       P       U      Pb      Th      Dy      Er       O   SUM 
   188    .528   1.211    .014    .053   2.440   8.014    .795    .323  24.076  11.885  11.466    .088    .260  12.347    .027   -.007  26.265  99.786
   189    .521   1.198    .007    .057   2.477   8.005    .828    .338  24.126  11.916  11.465    .095    .254  12.375    .054   -.012  26.274  99.976
   190    .518   1.214    .012    .051   2.450   8.000    .780    .285  24.248  12.029  11.384    .094    .265  12.372    .036   -.019  26.205  99.923

AVER:     .523   1.208    .011    .054   2.456   8.006    .801    .316  24.150  11.943  11.438    .092    .260  12.364    .039   -.012  26.248  99.895
SDEV:     .005    .009    .004    .003    .019    .007    .025    .027    .088    .076    .047    .004    .006    .015    .014    .006    .038    .098
SERR:     .003    .005    .002    .002    .011    .004    .014    .016    .051    .044    .027    .002    .003    .009    .008    .003    .022
%RSD:      .98     .71   34.90    5.63     .79     .09    3.07    8.54     .37     .63     .41    4.06    2.15     .12   35.32  -48.43     .14
STDS:      305     305     305    1016    1010    1009    1011    1005    1001    1007    1001      15      17      16    1002    1003     ---

STKF:    .0862   .1608   .1136   .4598   .5438   .5479   .5533   .5555   .5348   .5383   .0783   .8994   .7907   .7095   .5625   .5656     ---
STCT:   122.89  443.60  303.18   42.38   58.63   69.20   90.67  109.30   47.53   40.77   30.38  214.22  199.42  136.30  125.91  139.67     ---

UNKF:    .0049   .0062   .0000   .0003   .0222   .0721   .0071   .0026   .2155   .1056   .0695   .0008   .0020   .1108   .0003  -.0001     ---
UNCT:     6.99   17.11     .11     .03    2.39    9.10    1.16     .51   19.16    8.00   26.95     .20     .50   21.28     .07    -.02     ---
UNBG:     2.10    2.95    1.68     .24     .55     .69     .86     .98     .49     .40     .28    1.39     .67    1.07    1.20    1.49     ---

ZCOR:   1.0648  1.9470  2.5906  1.5934  1.1067  1.1109  1.1349  1.2078  1.1205  1.1305  1.6459  1.0838  1.3131  1.1161  1.2371  1.2401     ---
KRAW:    .0569   .0386   .0004   .0007   .0408   .1315   .0128   .0047   .4030   .1962   .8870   .0009   .0025   .1562   .0006  -.0002     ---
PKBG:     4.33    6.80    1.07    1.13    5.32   14.15    2.34    1.52   40.31   21.06   95.97    1.15    1.75   20.84    1.06     .98     ---
INT%:      .00   -3.89    -.03    ----  -24.57    -.90  -18.26  -85.44    ----    -.16    ----  -60.41    -.35    ----  -59.11   62.88     ---



Correction Method and Mass Absorption Coefficient File:
ZAF or Phi-Rho-Z Calculations
LINEMU   Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV

Current ZAF or Phi-Rho-Z Selection:
Armstrong/Love Scott (default)

Correction Selections:
Phi(pz) Absorption of Armstrong/Packwood-Brown 1981 MAS
Stopping Power of Love-Scott
Backscatter Coefficient of Love-Scott
Backscatter of Love-Scott
Mean Ionization of Berger-Seltzer
Phi(pz) Equation of Love-Scott
Reed/JTA w/ M-Line Correction and JTA Intensity Mod.
Fluorescence by Beta Lines NOT Included

Un   13 Montel Madagascar 6-1
TakeOff = 40.0  KiloVolt = 20.0  Beam Current = 150.  Beam Size =    5
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =        0, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00
Number of Data Lines:   3             Number of 'Good' Data Lines:   3
First/Last Date-Time: 09/10/2003 10:26:45 AM to 09/10/2003 11:00:49 AM

Average Total Oxygen:       26.249     Average Total Weight%:   99.901
Average Calculated Oxygen:  26.249     Average Atomic Number:   43.367
Average Excess Oxygen:        .000     Average Atomic Weight:   40.600
Average ZAF Iteration:        4.00     Average Quant Iterate:     4.00

Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction

Un   13 Montel Madagascar 6-1, Results in Elemental Weight Percents
 
ELEM:       Ca      Si      Al       Y      Pr      Nd      Sm      Gd      Ce      La       P       U      Pb      Th      Dy      Er       O
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    CALC
BGDS:      LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN     LIN
TIME:    40.00   40.00   40.00   40.00   40.00   40.00   40.00   40.00   20.00   20.00   20.00  240.00  240.00  240.00   80.00   80.00     ---
BEAM:   149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54  149.54     ---

ELEM:       Ca      Si      Al       Y      Pr      Nd      Sm      Gd      Ce      La       P       U      Pb      Th      Dy      Er       O   SUM 
   188    .528   1.212    .014    .053   2.440   8.014    .795    .323  24.076  11.886  11.466    .088    .260  12.350    .027   -.007  26.266  99.792
   189    .521   1.198    .007    .057   2.477   8.005    .828    .338  24.127  11.917  11.465    .095    .254  12.378    .054   -.012  26.275  99.982
   190    .518   1.214    .012    .051   2.450   8.000    .780    .285  24.248  12.030  11.384    .094    .265  12.375    .036   -.019  26.206  99.929

AVER:     .523   1.208    .011    .054   2.456   8.007    .801    .315  24.150  11.944  11.438    .092    .260  12.368    .039   -.012  26.249  99.901
SDEV:     .005    .009    .004    .003    .019    .007    .025    .027    .088    .076    .047    .004    .006    .015    .014    .006    .038    .098
SERR:     .003    .005    .002    .002    .011    .004    .014    .016    .051    .044    .027    .002    .003    .009    .008    .003    .022
%RSD:      .98     .71   34.90    5.63     .79     .09    3.07    8.54     .37     .63     .41    4.06    2.15     .12   35.33  -48.42     .14
STDS:      305     305     305    1016    1010    1009    1011    1005    1001    1007    1001      15      17      16    1002    1003     ---

STKF:    .0862   .1608   .1135   .4592   .5438   .5479   .5533   .5555   .5348   .5383   .0783   .8994   .7907   .7095   .5625   .5656     ---
STCT:   122.89  443.60  303.18   42.38   58.63   69.20   90.67  109.30   47.53   40.77   30.38  214.22  199.42  136.30  125.91  139.67     ---

UNKF:    .0049   .0062   .0000   .0003   .0222   .0721   .0071   .0026   .2155   .1056   .0695   .0008   .0020   .1108   .0003  -.0001     ---
UNCT:     6.99   17.11     .11     .03    2.39    9.10    1.16     .51   19.16    8.00   26.95     .20     .50   21.28     .07    -.02     ---
UNBG:     2.10    2.95    1.68     .24     .55     .69     .86     .98     .49     .40     .28    1.39     .67    1.07    1.20    1.49     ---

ZCOR:   1.0652  1.9481  2.5913  1.5946  1.1068  1.1109  1.1349  1.2078  1.1205  1.1306  1.6460  1.0842  1.3133  1.1164  1.2371  1.2401     ---
KRAW:    .0569   .0386   .0004   .0007   .0408   .1315   .0128   .0047   .4030   .1962   .8870   .0009   .0025   .1562   .0006  -.0002     ---
PKBG:     4.33    6.80    1.07    1.13    5.32   14.15    2.34    1.52   40.31   21.06   95.97    1.15    1.75   20.84    1.06     .98     ---
INT%:      .00   -3.89    -.03    ----  -24.57    -.90  -18.26  -85.44    ----    -.16    ----  -60.41    -.35    ----  -59.12   62.88     ---
The only stupid question is the one not asked!

Brian Joy

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Re: Reed Fluorescence Correction (Improved)
« Reply #2 on: May 23, 2015, 04:55:36 pm »
But consideration of fluorescence by Kb lines IS important for accurate quantification in certain cases, such as analysis of Mn in fayalitic olivine, Fe in cobaltite, or Co in pentlandite or heazlewoodite.

If you're using monazite as a test case, then I assume that you are also separating fluorescence effects of La and Lb1 lines in your improved correction?
« Last Edit: May 23, 2015, 05:08:02 pm by Brian Joy »
Brian Joy
Queen's University
Kingston, Ontario
JEOL JXA-8230

Probeman

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    • John Donovan
Re: Reed Fluorescence Correction (Improved)
« Reply #3 on: May 23, 2015, 11:02:25 pm »
But consideration of fluorescence by Kb lines IS important for accurate quantification in certain cases, such as analysis of Mn in fayalitic olivine, Fe in cobaltite, or Co in pentlandite or heazlewoodite.

Hi Brian,
Yes of course.  Fe ka by Ni comes to mind!  And that is exactly why I've made this request:

http://probesoftware.com/smf/index.php?topic=47.msg2768#msg2768

If you're using monazite as a test case, then I assume that you are also separating fluorescence effects of La and Lb1 lines in your improved correction?

The monazite analysis is a just a handy composition I use for testing a large number of corrections in my software for internal accuracy.

As for L line fluorescence effects I separate all these like this:

        ' Variable fluor_type2%() is code for type of fluorescence:  0 = none
        ' 1=Ka by Ka  2=Ka by Kb  3=Ka by La  4=Ka by Lb  5=Ka by Ma  6=Ka by Mb
        ' 7=Kb by Ka  8=Kb by Kb  9=Kb by La 10=Kb by Lb 11=Kb by Ma 12=Kb by Mb
        '13=La by Ka 14=La by Kb 15=La by La 16=La by Lb 17=La by Ma 18=La by Mb
        '19=Lb by Ka 20=Lb by Kb 21=Lb by La 22=Lb by Lb 23=Lb by Ma 24=Lb by Mb
        '25=Ma by Ka 26=Ma by Kb 27=Ma by La 28=Ma by Lb 29=Ma by Ma 30=Ma by Mb
        '31=Mb by Ka 32=Mb by Kb 33=Mb by La 34=Mb by Lb 35=Mb by Ma 36=Mb by Mb


It's not completely rigorous, but it's a significant improvement over previous analytical efforts. Note I define these transition as this:

"K L3"        (Ka)
"K M3"        (Kb)
"L3 M5"       (La)
"L2 M4"       (Lb)
"M5 N7"       (Ma)
"M4 N6"       (Mb)

Of course, if one prefers full rigor, then a quantum mechanical Monte Carlo method such as Penepma is the way to go.  I'm about 1/3 of the way through the entire periodic table calculating k-ratios for binary systems which are then combined in seconds for on-line analyses. My most recent efforts in this area are described in more detail here:

http://probesoftware.com/smf/index.php?topic=47.msg2680#msg2680

And that was before I implemented the non-linear alpha fit as seen here:

http://probesoftware.com/smf/index.php?topic=239.msg2763#msg2763

which is very important for situation with extreme fluorescence (and absorption) effects. The problem for modeling fluorescence corrections is as you know, the lack of decent measurements of highly fluoresced systems to check the models. Hence my measurement request above...

But as the Penepma alpha factor topic link above shows, a 2.8% error distribution standard deviation at 0.9928 accuracy (Pouchou dataset) is pretty darn good. And this Penepma Monte Carlo parameterization performs on-line calculations in seconds.

So in another year or so I'll have the complete periodic table. After that... well we always need more precision!

For all, attached below is a chart I find helpful.
« Last Edit: May 24, 2015, 08:00:58 am by Probeman »
The only stupid question is the one not asked!

Probeman

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    • John Donovan
Re: Reed Fluorescence Correction (Improved)
« Reply #4 on: May 24, 2015, 07:55:54 am »
The point of the above post being more that even in a relatively complex composition as monazite with significant high Z element emissions going every which way, we still see only a small contribution from beta fluorescence.

As for a system more along the lines (pun intended!), which Brian mentioned here is an example of a high alloy steel, first with fluorescence *with* beta lines:

Correction Method and Mass Absorption Coefficient File:
ZAF or Phi-Rho-Z Calculations
LINEMU   Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV

Current ZAF or Phi-Rho-Z Selection:
Armstrong/Love Scott (default)

Correction Selections:
Phi(pz) Absorption of Armstrong/Packwood-Brown 1981 MAS
Stopping Power of Love-Scott
Backscatter Coefficient of Love-Scott
Backscatter of Love-Scott
Mean Ionization of Berger-Seltzer
Phi(pz) Equation of Love-Scott
Reed/JTA w/ M-Line Correction and JTA Intensity Mod.
Fluorescence by Beta Lines Included


St  651 Set   2 NIST SRM C2402 (Hastelloy C)
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 30.0  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00

High temperature alloy
Number of Data Lines:   5             Number of 'Good' Data Lines:   5
First/Last Date-Time: 03/14/2015 08:09:05 PM to 03/14/2015 08:20:58 PM
WARNING- Using Exponential Off-Peak correction for cr ka

Average Total Oxygen:         .000     Average Total Weight%:   98.011
Average Calculated Oxygen:    .000     Average Atomic Number:   31.181
Average Excess Oxygen:        .000     Average Atomic Weight:   62.245
Average ZAF Iteration:        3.00     Average Quant Iterate:     2.00

St  651 Set   2 NIST SRM C2402 (Hastelloy C), Results in Elemental Weight Percents

SPEC:       Co      Si      Mn       V      Cu
TYPE:     SPEC    SPEC    SPEC    SPEC    SPEC

AVER:    1.500    .850    .640    .220    .190
SDEV:     .000    .000    .000    .000    .000
 
ELEM:       Fe      Ni      Cr      Mo       W
BGDS:      LIN     LIN     EXP     LIN     LIN
TIME:   100.00  100.00  100.00  100.00  100.00
BEAM:    29.84   29.84   29.84   29.84   29.84

ELEM:       Fe      Ni      Cr      Mo       W   SUM 
   207   7.607  52.452  16.336  14.459   3.857  98.111
   208   7.377  51.317  16.431  15.585   3.698  97.808
   209   7.501  52.075  16.397  14.743   3.799  97.915
   210   6.505  46.098  16.133  21.935   4.225  98.296
   211   7.317  51.365  16.461  15.703   3.679  97.925

AVER:    7.261  50.662  16.352  16.485   3.852  98.011
SDEV:     .437   2.596    .131   3.093    .221    .193
SERR:     .196   1.161    .058   1.383    .099
%RSD:     6.02    5.12     .80   18.76    5.75

PUBL:    7.300  51.500  16.150  17.100   4.290  99.740
%VAR:     -.53   -1.63    1.25   -3.60  -10.22
DIFF:    -.039   -.838    .202   -.615   -.438
STDS:      526     528     524     542     574

STKF:   1.0000  1.0000   .9988   .9910   .9979
STCT:   6346.7 20768.3 15241.3  8726.4  2235.2

UNKF:    .0797   .5171   .1722   .1346   .0269
UNCT:    505.7 10739.8  2627.0  1185.5    60.4
UNBG:     19.5   118.8    71.3    14.9     4.7

ZCOR:    .9115   .9795   .9498  1.2257  1.4303
KRAW:    .0797   .5171   .1724   .1359   .0270
PKBG:    26.98   91.45   37.85   80.39   13.83


And next *without* fluorescence by beta lines:

Correction Method and Mass Absorption Coefficient File:
ZAF or Phi-Rho-Z Calculations
LINEMU   Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV

Current ZAF or Phi-Rho-Z Selection:
Armstrong/Love Scott (default)

Correction Selections:
Phi(pz) Absorption of Armstrong/Packwood-Brown 1981 MAS
Stopping Power of Love-Scott
Backscatter Coefficient of Love-Scott
Backscatter of Love-Scott
Mean Ionization of Berger-Seltzer
Phi(pz) Equation of Love-Scott
Reed/JTA w/ M-Line Correction and JTA Intensity Mod.
Fluorescence by Beta Lines NOT Included


St  651 Set   2 NIST SRM C2402 (Hastelloy C)
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 30.0  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00

High temperature alloy
Number of Data Lines:   5             Number of 'Good' Data Lines:   5
First/Last Date-Time: 03/14/2015 08:09:05 PM to 03/14/2015 08:20:58 PM
WARNING- Using Exponential Off-Peak correction for cr ka

Average Total Oxygen:         .000     Average Total Weight%:   98.158
Average Calculated Oxygen:    .000     Average Atomic Number:   31.171
Average Excess Oxygen:        .000     Average Atomic Weight:   62.230
Average ZAF Iteration:        3.00     Average Quant Iterate:     2.00

St  651 Set   2 NIST SRM C2402 (Hastelloy C), Results in Elemental Weight Percents

SPEC:       Co      Si      Mn       V      Cu
TYPE:     SPEC    SPEC    SPEC    SPEC    SPEC

AVER:    1.500    .850    .640    .220    .190
SDEV:     .000    .000    .000    .000    .000
 
ELEM:       Fe      Ni      Cr      Mo       W
BGDS:      LIN     LIN     EXP     LIN     LIN
TIME:   100.00  100.00  100.00  100.00  100.00
BEAM:    29.84   29.84   29.84   29.84   29.84

ELEM:       Fe      Ni      Cr      Mo       W   SUM 
   207   7.673  52.461  16.419  14.459   3.856  98.267
   208   7.439  51.326  16.511  15.586   3.697  97.959
   209   7.566  52.084  16.479  14.743   3.798  98.070
   210   6.553  46.106  16.200  21.936   4.225  98.419
   211   7.379  51.374  16.541  15.703   3.678  98.075

AVER:    7.322  50.670  16.430  16.485   3.851  98.158
SDEV:     .445   2.596    .136   3.093    .221    .183
SERR:     .199   1.161    .061   1.383    .099
%RSD:     6.07    5.12     .83   18.76    5.75

PUBL:    7.300  51.500  16.150  17.100   4.290  99.740
%VAR:      .30   -1.61    1.73   -3.59  -10.24
DIFF:     .022   -.830    .280   -.615   -.439
STDS:      526     528     524     542     574

STKF:   1.0000  1.0000   .9988   .9910   .9976
STCT:   6346.7 20768.3 15241.3  8726.4  2235.2

UNKF:    .0797   .5171   .1722   .1346   .0269
UNCT:    505.7 10739.8  2627.0  1185.5    60.4
UNBG:     19.5   118.8    71.3    14.9     4.7

ZCOR:    .9191   .9797   .9544  1.2257  1.4304
KRAW:    .0797   .5171   .1724   .1359   .0270
PKBG:    26.98   91.45   37.85   80.39   13.83


The largest effects as expected for Fe ka and Cr Ka, both highly fluoresced by beta lines.
The only stupid question is the one not asked!

Brian Joy

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Re: Reed Fluorescence Correction (Improved)
« Reply #5 on: May 24, 2015, 09:29:41 am »
But consideration of fluorescence by Kb lines IS important for accurate quantification in certain cases, such as analysis of Mn in fayalitic olivine, Fe in cobaltite, or Co in pentlandite or heazlewoodite.

Just to clarify, I was trying to point out some cases in which the measured X-ray (respectively Mn Ka, Fe Ka, or Co Ka) is fluoresced by a Kb line of a matrix element, but NOT by the Ka line.  For instance, for the last case, the energy of the Co K edge falls between that of Ni Ka and Ni Kb.  The problem is exacerbated by the fact that the measured element is present in relatively low concentration relative to the fluorescing element.  For instance, heazlewoodite (nominally Ni3S2) might contain ~71 wt% Ni and ~2 wt% Co.  When analyzed using a 20 kV potential, the intensity of Co Ka produced by secondary fluorescence (due entirely to Ni Kb) is about 3.4% of the primary Co Ka intensity.

Also, when considering measurement of transition metal K lines (or virtually any X-ray that can be diffracted by LiF), the continuum fluorescence correction can also be significant.  Do you have any plans to add this correction to CalcZAF?
Brian Joy
Queen's University
Kingston, Ontario
JEOL JXA-8230

Probeman

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    • John Donovan
Re: Reed Fluorescence Correction (Improved)
« Reply #6 on: May 24, 2015, 11:47:46 am »
But consideration of fluorescence by Kb lines IS important for accurate quantification in certain cases, such as analysis of Mn in fayalitic olivine, Fe in cobaltite, or Co in pentlandite or heazlewoodite.

Just to clarify, I was trying to point out some cases in which the measured X-ray (respectively Mn Ka, Fe Ka, or Co Ka) is fluoresced by a Kb line of a matrix element, but NOT by the Ka line.  For instance, for the last case, the energy of the Co K edge falls between that of Ni Ka and Ni Kb.  The problem is exacerbated by the fact that the measured element is present in relatively low concentration relative to the fluorescing element.  For instance, heazlewoodite (nominally Ni3S2) might contain ~71 wt% Ni and ~2 wt% Co.  When analyzed using a 20 kV potential, the intensity of Co Ka produced by secondary fluorescence (due entirely to Ni Kb) is about 3.4% of the primary Co Ka intensity.

Also, when considering measurement of transition metal K lines (or virtually any X-ray that can be diffracted by LiF), the continuum fluorescence correction can also be significant.  Do you have any plans to add this correction to CalcZAF?

Hi Brian,
Yup, those are cases of significant fluorescence by beta lines.

The continuum fluorescence correction is fully implemented in the Penepma alpha factor matrix correction.  The continuum fluorescence cannot be included in the normal Phi-rho-z calculations because historically it was "inadvertently incorporated" into the absorption analytical models!  So adding it in now just makes things worse!

A good test is to run such a suspected case of large continuum fluorescence using both analytical and Penepma Monte Carlo alpha factor models and note the differences in the matrix corrections.

Easy to do in CalcZAF!
The only stupid question is the one not asked!

Brian Joy

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Re: Reed Fluorescence Correction (Improved)
« Reply #7 on: May 24, 2015, 03:24:48 pm »
The continuum fluorescence cannot be included in the normal Phi-rho-z calculations because historically it was "inadvertently incorporated" into the absorption analytical models!  So adding it in now just makes things worse!

Can you elaborate on this?
Brian Joy
Queen's University
Kingston, Ontario
JEOL JXA-8230

Probeman

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    • John Donovan
Re: Reed Fluorescence Correction (Improved)
« Reply #8 on: May 24, 2015, 04:34:13 pm »
The continuum fluorescence cannot be included in the normal Phi-rho-z calculations because historically it was "inadvertently incorporated" into the absorption analytical models!  So adding it in now just makes things worse!

Can you elaborate on this?

Just that I've been told this by John Armstrong a while back. Apparently because earlier work on analytical expressions didn't treat the continuum fluorescence separately, it got (very poorly) accounted for in the absorption corrections which were tuned to various data sets.
john
The only stupid question is the one not asked!

Probeman

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    • John Donovan
Re: Reed Fluorescence Correction (Improved)
« Reply #9 on: July 20, 2015, 04:06:38 pm »
After a couple of minor tweaks to the Ka by Ma/Mb relative line weights in the (improved) Reed fluorescence correction, the Pouchou database error distribution now looks like this:



This can be compared to the error distribution using the previous code as seen in the first screen snap in this post:

http://probesoftware.com/smf/index.php?topic=47.msg3060#msg3060

So a small improvement in the average and variance.  If I run the large flu correction "database" from Penepma12 calculations we now get this:



This should be compared to the previous calculation (2nd screen snap) in this post:

http://probesoftware.com/smf/index.php?topic=490.msg2710#msg2710

and again we see a small but significant improvement in the "further improved" Reed fluorescence correction.
The only stupid question is the one not asked!

Probeman

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    • John Donovan
Re: Reed Fluorescence Correction (Improved)
« Reply #10 on: July 23, 2015, 01:27:31 pm »
Ok, after further "tuning" of the Reed relative line weights to Penepma k-ratios I now get this for the Pouchou database:



This is a slightly better (smaller) variance than the previous attempt (see first plot in this post):

http://probesoftware.com/smf/index.php?topic=490.msg3085#msg3085

Now all this is a little silly as the Pouchou database was selected to *minimize* fluorescence effects, so what if we use a better MAC table such as FFAST?  Here you go:



Now that's a bit better!  Actually slightly better (smaller) variance than the Penepma alpha method shown here:

http://probesoftware.com/smf/index.php?topic=47.msg3105#msg3105

but with a worse average error than the Penepma alpha method.  So this is looking promising if one is using the best MACs.

I'll also speculate about the high average error (greater than 1.000) compared to Penepma, and have to wonder that if because they were using a fairly primitive fluorescence correction when they were "tuning" the phi-rho-z analytical models, they didn't inadvertently compensate for some fluorescence problems with the ZA correction?
« Last Edit: July 23, 2015, 01:55:21 pm by Probeman »
The only stupid question is the one not asked!