What do I mean by "Non Physical EPMA"?
Well, basically any time the user is attempting to measure the same element with multiple spectrometers and/or EDS we have the potential for a non physical situation where the matrix may not be calculated with perfect rigor due to the same element being included in the matrix correction more than once.
Obviously, one should attempt to eliminate the potential for duplicate elements in the matrix correction physics by utilizing either the "disable quant" option for the duplicate elements for the unknown samples! as described here:
http://smf.probesoftware.com/index.php?topic=155.msg646#msg646
or instead simply utilize the "aggregate intensity" feature as described here:
http://smf.probesoftware.com/index.php?topic=29.msg387#msg387
With the caveat that the aggregate intensity feature can only aggregate intensities that are from the same element and x-ray, though they can have different Bragg analyzing crystals utilized.
However, there are situations where the presence of duplicate elements are necessary for improved precision, but the user wants to examine the statistics for each duplicate elements without aggregation. In these cases we might want to know what the effect of the duplicate elements in the matrix correction is exactly...
Let's start by looking at a Ti in quartz analysis where Ti was measured on all 5 spectrometers for maximum geometric efficiency as seen here for the TiO2 standard:
St 922 Set 1 TiO2 (elemental) (#22), Results in Elemental Weight Percents
ELEM: Ti Ti Ti Ti Ti Si O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN LIN LIN LIN
TIME: 100.00 100.00 100.00 100.00 100.00
BEAM: 199.60 199.60 199.60 199.60 199.60
ELEM: Ti Ti Ti Ti Ti Si O SUM
XRAY: (ka) (ka) (ka) (ka) (ka) () ()
6 57.2174 57.3757 57.3689 57.5892 57.4592 .00000 40.0000 327.010
7 57.3874 57.3667 57.3167 57.4705 57.3516 .00000 40.0000 326.893
8 57.4199 57.2974 57.3111 57.3568 57.3109 .00000 40.0000 326.696
9 57.3539 57.3642 57.3707 57.2694 57.3508 .00000 40.0000 326.709
10 57.4238 57.3985 57.4350 57.1164 57.3299 .00000 40.0000 326.704
AVER: 57.3605 57.3605 57.3605 57.3605 57.3605 .000 40.000 326.802
SDEV: .08484 .03780 .05021 .18185 .05770 .000 .000 .14250
SERR: .03794 .01690 .02246 .08133 .02581 .00000 .00000
%RSD: .14791 .06589 .08754 .31703 .10060 .00000 .00000
PUBL: 59.9900 59.9900 59.9900 59.9900 59.9900 n.a. 40.0000 99.9900
%VAR: (-4.38) (-4.38) (-4.38) (-4.38) (-4.38) --- .00
DIFF: (-2.63) (-2.63) (-2.63) (-2.63) (-2.63) --- .00000
STDS: 922 922 922 922 922 0 0
STKF: .5621 .5621 .5621 .5621 .5621 .0000 .0000
STCT: 667.34 1600.07 1901.70 531.93 828.32 .00 .00
UNKF: .5621 .5621 .5621 .5621 .5621 .0000 .0000
UNCT: 667.34 1600.07 1901.70 531.93 828.32 .00 .00
UNBG: 2.12 5.17 7.04 1.70 3.41 .00 .00
ZCOR: 1.0204 1.0204 1.0204 1.0204 1.0204 .0000 .0000
KRAW: 1.00000 1.00000 1.00000 1.00000 1.00000 .00000 .00000
So, besides the fact that the total is obviously over 100%, we do observe that the "measured" Ti concentrations are off significantly, even though the standard k-factor is calculated correctly for Ti ka in TiO2 at 20 keV (0.5621) for each duplicate Ti element. Why is this? Because the ZAFCOR (Phi-RhoZ in this case) is *incorrect* due to the incorrect ratio of Ti to O in the specified matrix (because we added in Ti 5 times and oxygen only once!).
So again, we can use the disable quant or aggregate intensity feature to have the standard calculated correctly as seen here:
St 922 Set 1 TiO2 (elemental) (#22), Results in Elemental Weight Percents
ELEM: Ti Ti Ti Ti Ti Si O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC
BGDS: LIN LIN LIN LIN LIN
TIME: 100.00 .00 .00 .00 .00
BEAM: 199.60 .00 .00 .00 .00
AGGR: 5
ELEM: Ti Ti Ti Ti Ti Si O SUM
XRAY: (ka) (ka) (ka) (ka) (ka) () ()
6 60.0175 .00000 .00000 .00000 .00000 .00000 40.0000 100.018
7 59.9893 .00000 .00000 .00000 .00000 .00000 40.0000 99.9893
8 59.9532 .00000 .00000 .00000 .00000 .00000 40.0000 99.9532
9 59.9829 .00000 .00000 .00000 .00000 .00000 40.0000 99.9829
10 60.0057 .00000 .00000 .00000 .00000 .00000 40.0000 100.006
AVER: 59.9897 .00000 .00000 .00000 .00000 .000 40.000 99.9897
SDEV: .02453 .00000 .00000 .00000 .00000 .000 .000 .02453
SERR: .01097 .00000 .00000 .00000 .00000 .00000 .00000
%RSD: .04088 .00000 .00000 .00000 .00000 .00000 .00000
PUBL: 59.9900 n.a. n.a. n.a. n.a. n.a. 40.0000 99.9900
%VAR: (.00) (.00) (.00) (.00) (.00) --- .00
DIFF: (.00) .00 .00 .00 .00 --- .00000
STDS: 922 0 0 0 0 0 0
STKF: .5621 0 0 0 0 .0000 .0000
STCT: 5529.37 .00 .00 .00 .00 .00 .00
UNKF: .5621 .0000 .0000 .0000 .0000 .0000 .0000
UNCT: 5529.37 .00 .00 .00 .00 .00 .00
UNBG: 19.44 .00 .00 .00 .00 .00 .00
ZCOR: 1.0672 .0000 .0000 .0000 .0000 .0000 .0000
And now we see that the ZAFCOR matrix correction for Ti ka in TiO2 is calculated correctly (1.0672).
But what about our unknown quartz samples? How much does it matter in that situation if we don't "aggregate"? Here is the quartz blank standard (1.42 PPM Ti) without the aggregate intensity feature:
Un 31 1920 sec on SiO2, Results in Elemental Weight Percents
ELEM: Ti Ti Ti Ti Ti Si O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC CALC
BGDS: LIN LIN LIN LIN LIN
TIME: 1920.00 1920.00 1920.00 1920.00 1920.00
BEAM: 200.76 200.76 200.76 200.76 200.76
ELEM: Ti Ti Ti Ti Ti Si O SUM
XRAY: (ka) (ka) (ka) (ka) (ka) () ()
271 -.00003 .00039 .00003 -.00006 .00051 46.7430 53.2576 100.001
272 .00010 .00039 .00022 -.00036 -.00030 46.7430 53.2570 100.000
273 .00003 .00037 .00008 .00007 .00048 46.7430 53.2577 100.002
274 .00002 .00016 .00015 -.00005 .00009 46.7430 53.2572 100.001
275 -.00010 .00019 -.00002 .00016 .00009 46.7430 53.2572 100.001
AVER: .00000 .00030 .00009 -.00005 .00017 46.743 53.257 100.001
SDEV: .00007 .00011 .00010 .00020 .00034 .000 .000 .00067
SERR: .00003 .00005 .00004 .00009 .00015 .00000 .00012
%RSD: 4057.70 37.3350 103.073 -404.32 193.525 .00000 .00050
STDS: 922 922 922 922 922 0 0
STKF: .5621 .5621 .5621 .5621 .5621 .0000 .0000
STCT: 667.34 1600.07 1901.70 531.93 828.32 .00 .00
UNKF: .0000 .0000 .0000 .0000 .0000 .0000 .0000
UNCT: .00 .01 .00 .00 .00 .00 .00
UNBG: .99 2.63 3.41 .79 1.38 .00 .00
ZCOR: 1.1969 1.1969 1.1969 1.1969 1.1969 .0000 .0000
So now we see the standard k-factor is still calculated correctly, and the ZAFCOR matrix correction is also very close to the anticipated value.
Un 31 1920 sec on SiO2, Results in Elemental Weight Percents
ELEM: Ti Ti Ti Ti Ti Si O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC CALC
BGDS: LIN LIN LIN LIN LIN
TIME: 1920.00 .00 .00 .00 .00
BEAM: 200.76 .00 .00 .00 .00
AGGR: 5
ELEM: Ti Ti Ti Ti Ti Si O SUM
XRAY: (ka) (ka) (ka) (ka) (ka) () ()
271 .00019 .00000 .00000 .00000 .00000 46.7430 53.2571 100.000
272 .00012 .00000 .00000 .00000 .00000 46.7430 53.2571 100.000
273 .00022 .00000 .00000 .00000 .00000 46.7430 53.2571 100.000
274 .00011 .00000 .00000 .00000 .00000 46.7430 53.2571 100.000
275 .00007 .00000 .00000 .00000 .00000 46.7430 53.2570 100.000
AVER: .00014 .00000 .00000 .00000 .00000 46.743 53.257 100.000
SDEV: .00006 .00000 .00000 .00000 .00000 .000 .000 .00011
SERR: .00003 .00000 .00000 .00000 .00000 .00000 .00002
%RSD: 43.8974 .00000 .00000 .00000 .00000 .00000 .00008
STDS: 922 0 0 0 0 0 0
STKF: .5621 0 0 0 0 .0000 .0000
STCT: 5529.37 .00 .00 .00 .00 .00 .00
UNKF: .0000 .0000 .0000 .0000 .0000 .0000 .0000
UNCT: .01 .00 .00 .00 .00 .00 .00
UNBG: 9.21 .00 .00 .00 .00 .00 .00
ZCOR: 1.1969 .0000 .0000 .0000 .0000 .0000 .0000
What if we aggregate the Ti ka and Al ka intensities? As we can see the ZAFCOR matrix correction hasn't changed because the Ti is essentially at zero concentrations. Now what about a real world sample? Here is the Audetat SiO2 standard without aggregate intensities turned on:
Un 4 Rusk sample, Results in Elemental Weight Percents
SPEC: Si O
TYPE: DIFF CALC
AVER: 46.707 53.251
SDEV: .002 .000
ELEM: Ti Ti Al Al
BGDS: LIN LIN EXP EXP
TIME: 400.00 400.00 400.00 400.00
BEAM: 100.05 100.05 100.05 100.05
ELEM: Ti Ti Al Al SUM
XRAY: (ka) (ka) (ka) (ka)
114 .00446 .00524 .01576 .01530 100.000
115 .00409 .00526 .01537 .01563 100.000
116 .00536 .00507 .01569 .01509 100.000
117 .00640 .00588 .01592 .01510 100.000
118 .00561 .00620 .01482 .01554 100.000
119 .00558 .00523 .01502 .01564 100.000
120 .00487 .00548 .01637 .01539 100.000
121 .00604 .00602 .01555 .01504 100.000
122 .00639 .00672 .01702 .01557 100.000
123 .00508 .00504 .01536 .01566 100.000
124 .00771 .00698 .01616 .01589 100.000
125 .00465 .00539 .01597 .01579 100.000
126 .00375 .00532 .01637 .01561 100.000
127 .00400 .00466 .01628 .01609 100.000
128 .00427 .00542 .01588 .01568 100.000
129 .00341 .00399 .01341 .01221 100.000
130 .00429 .00576 .01578 .01586 100.000
131 .00279 .00653 .01617 .01583 100.000
132 .00653 .00568 .01671 .01595 100.000
133 .00485 .00656 .01604 .01564 100.000
134 .00511 .00642 .01531 .01574 100.000
135 .00606 .00626 .01572 .01549 100.000
136 .00556 .00537 .01525 .01528 100.000
137 .00499 .00533 .01583 .01512 100.000
138 .00536 .00520 .01604 .01527 100.000
139 .00496 .00712 .01634 .01567 100.000
140 .00635 .00653 .01580 .01568 100.000
141 .00320 .00680 .01495 .01534 100.000
142 .00457 .00535 .01436 .01447 100.000
AVER: .00504 .00575 .01570 .01540 100.000
SDEV: .00111 .00075 .00073 .00070 .00000
SERR: .00021 .00014 .00013 .00013
%RSD: 22.0325 12.9763 4.61999 4.55493
STDS: 22 22 374 374
STKF: .5616 .5616 .0626 .0626
STCT: 103.63 374.70 147.71 503.19
UNKF: .0000 .0000 .0001 .0001
UNCT: .01 .03 .27 .91
UNBG: .07 .25 1.15 3.89
ZCOR: 1.1969 1.1969 1.3538 1.3538
And here is the same Audetat sample again with the aggregate intensity feature turned on:
Un 4 Rusk sample, Results in Elemental Weight Percents
SPEC: Si O
TYPE: DIFF CALC
AVER: 46.725 53.254
SDEV: .001 .000
ELEM: Ti Ti Al Al
BGDS: LIN LIN EXP EXP
TIME: 400.00 .00 400.00 .00
BEAM: 100.05 .00 100.05 .00
AGGR: 2 2
ELEM: Ti Ti Al Al SUM
XRAY: (ka) (ka) (ka) (ka)
114 .00507 .00000 .01540 .00000 100.000
115 .00501 .00000 .01557 .00000 100.000
116 .00513 .00000 .01523 .00000 100.000
117 .00599 .00000 .01529 .00000 100.000
118 .00607 .00000 .01538 .00000 100.000
119 .00530 .00000 .01550 .00000 100.000
120 .00535 .00000 .01562 .00000 100.000
121 .00602 .00000 .01516 .00000 100.000
122 .00665 .00000 .01590 .00000 100.000
123 .00504 .00000 .01559 .00000 100.000
124 .00714 .00000 .01595 .00000 100.000
125 .00523 .00000 .01583 .00000 100.000
126 .00497 .00000 .01578 .00000 100.000
127 .00451 .00000 .01614 .00000 100.000
128 .00517 .00000 .01572 .00000 100.000
129 .00387 .00000 .01248 .00000 100.000
130 .00544 .00000 .01584 .00000 100.000
131 .00571 .00000 .01591 .00000 100.000
132 .00586 .00000 .01612 .00000 100.000
133 .00619 .00000 .01573 .00000 100.000
134 .00613 .00000 .01564 .00000 100.000
135 .00621 .00000 .01554 .00000 100.000
136 .00541 .00000 .01527 .00000 100.000
137 .00526 .00000 .01528 .00000 100.000
138 .00523 .00000 .01544 .00000 100.000
139 .00664 .00000 .01582 .00000 100.000
140 .00649 .00000 .01571 .00000 100.000
141 .00601 .00000 .01525 .00000 100.000
142 .00518 .00000 .01444 .00000 100.000
AVER: .00560 .00000 .01547 .00000 100.000
SDEV: .00070 .00000 .00067 .00000 .00000
SERR: .00013 .00000 .00012 .00000
%RSD: 12.5764 .00000 4.33292 .00000
STDS: 22 0 374 0
STKF: .5616 0 .0626 0
STCT: 478.33 .00 650.90 .00
UNKF: .0000 .0000 .0001 .0000
UNCT: .04 .00 1.19 .00
UNBG: .32 .00 5.04 .00
ZCOR: 1.1969 .0000 1.3537 .0000
Note that the Ti ka ZAFCOR did not change with 5 digits of precision, but the Al ka ZAFCOR changed from 1.3538 to 1.3537, so no significant change there.
The bottom line: duplicate elements can introduce systematic accuracy errors if the duplicate elements are not disabled for quant or utilizing the aggregate intensity feature, but it depends on the physics details including the concentrations and absorption correction magnitudes.
This is an old topic but relevant for this post on using duplicate elements with different x-ray lines where the matrix correction will be affected by duplication of a major element quantification.
Note that in this situation, where the element is duplicated but where the x-ray lines are different, we *cannot* utilize the "aggregate mode" feature in Probe for EPMA (as described in the previous post), because the photons are not the same energy.
And as above, if both duplicate elements are enabled for quantification, and the element is present in a significant concentration (in this example Fe Ka and Fe La in olivine), the totals will be will be excessively high and the matrix correction incorrectly calculated. But if either of the Fe channels are disabled for quantification (using the Disable Quant checkbox in the Elements/Cations dialog), the software should be able to correctly calculate the matrix correction.
That also means that the standard k-factor has to be calculated appropriately and there was a small bug (as Ben Buse and Gareth Seward independently pointed out to me) preventing that, which is now fixed (Gareth had previously sent me a similar example of W La and W Ma measured at the same time).
So here are the results of an olivine analysis with both Fe Ka and Fe La acquired, first with Fe Ka enabled and Fe La disabled:
Un 14 fayalite
TakeOff = 40.0 KiloVolt = 10.0 Beam Current = 200. Beam Size = 1
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 1000, Magnification (imaging) = 100)
Image Shift (X,Y): .00, .00
Number of Data Lines: 17 Number of 'Good' Data Lines: 17
First/Last Date-Time: 10/17/2017 06:56:23 PM to 10/17/2017 07:20:40 PM
WARNING- Using Exponential Off-Peak correction for Mg kb
WARNING- Quantitation is Disabled For Fe la, Spectro 1
Average Total Oxygen: 31.370 Average Total Weight%: 100.288
Average Calculated Oxygen: 31.370 Average Atomic Number: 18.697
Average Excess Oxygen: .000 Average Atomic Weight: 29.166
Average ZAF Iteration: 2.00 Average Quant Iterate: 2.00
Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.
Un 14 fayalite, Results in Elemental Weight Percents
ELEM: Fe Ca Fe Mn Si Mg O
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL CALC
BGDS: LIN LIN LIN LIN LIN EXP
TIME: --- 10.00 10.00 10.00 10.00 10.00 ---
BEAM: --- 199.06 199.06 199.06 199.06 199.06 ---
ELEM: Fe-D Ca Fe Mn Si Mg O SUM
XRAY: (la) (ka) (ka) (ka) (ka) (kb) ()
672 --- .109 52.006 3.080 13.502 .439 31.512 100.648
673 --- .105 52.374 3.107 13.477 -.403 31.041 99.700
674 --- .104 52.017 3.033 13.573 -.005 31.289 100.010
675 --- .105 52.100 3.008 13.524 -.503 30.922 99.156
676 --- .098 52.318 2.975 13.568 .223 31.501 100.684
677 --- .107 52.144 2.993 13.796 .139 31.663 100.842
678 --- .111 51.947 3.031 13.696 .577 31.795 101.159
679 --- .106 52.395 3.008 13.576 .128 31.482 100.695
680 --- .104 52.090 3.021 13.586 .023 31.339 100.162
681 --- .102 52.088 2.963 13.390 .539 31.437 100.520
682 --- .105 52.398 3.069 13.363 -.245 31.012 99.701
683 --- .114 52.227 3.033 13.678 .648 31.902 101.603
684 --- .094 52.309 2.975 13.731 .051 31.568 100.727
685 --- .110 51.914 3.079 13.539 .450 31.535 100.627
686 --- .111 52.122 3.024 13.342 -.482 30.742 98.859
687 --- .103 52.071 2.935 13.648 .338 31.586 100.681
688 --- .113 51.739 3.014 13.446 -.156 30.964 99.120
AVER: --- .106 52.133 3.021 13.555 .104 31.370 100.288
SDEV: --- .005 .185 .045 .129 .370 .328 .759
SERR: --- .001 .045 .011 .031 .090 .080
%RSD: --- 4.88 .35 1.51 .95 357.09 1.05
STDS: --- 804 1010 818 803 803 ---
STKF: --- .3188 .4636 1.0000 .1546 .2591 ---
STCT: --- 326.01 63.05 117.44 9.34 2.50 ---
UNKF: --- .0011 .4644 .0266 .1207 .0007 ---
UNCT: --- 1.09 63.15 3.12 7.29 .01 ---
UNBG: --- 1.96 .75 .27 .15 .74 ---
ZCOR: --- .9927 1.1226 1.1365 1.1232 1.3948 ---
KRAW: --- .0033 1.0016 .0266 .7805 .0029 ---
PKBG: --- 1.56 84.95 12.74 50.06 1.01 ---
And now the same unknown sample but with Fe Ka disabled and Fe La enabled:
Un 14 fayalite
TakeOff = 40.0 KiloVolt = 10.0 Beam Current = 200. Beam Size = 1
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 1000, Magnification (imaging) = 100)
Image Shift (X,Y): .00, .00
Number of Data Lines: 17 Number of 'Good' Data Lines: 17
First/Last Date-Time: 10/17/2017 06:56:23 PM to 10/17/2017 07:20:40 PM
WARNING- Using Exponential Off-Peak correction for Mg kb
WARNING- Quantitation is Disabled For Fe ka, Spectro 4
Average Total Oxygen: 31.391 Average Total Weight%: 100.195
Average Calculated Oxygen: 31.391 Average Atomic Number: 18.679
Average Excess Oxygen: .000 Average Atomic Weight: 29.135
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.
Un 14 fayalite, Results in Elemental Weight Percents
ELEM: Fe Ca Fe Mn Si Mg O
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL CALC
BGDS: LIN LIN LIN LIN LIN EXP
TIME: 10.00 10.00 --- 10.00 10.00 10.00 ---
BEAM: 199.06 199.06 --- 199.06 199.06 199.06 ---
ELEM: Fe Ca Fe-D Mn Si Mg O SUM
XRAY: (la) (ka) (ka) (ka) (ka) (kb) ()
672 51.705 .109 --- 3.081 13.565 .431 31.494 100.386
673 50.470 .105 --- 3.111 13.536 -.396 30.569 97.395
674 52.043 .104 --- 3.033 13.638 -.005 31.370 100.184
675 51.706 .105 --- 3.009 13.588 -.494 30.888 98.802
676 52.860 .098 --- 2.975 13.634 .220 31.729 101.515
677 51.718 .107 --- 2.994 13.861 .137 31.614 100.430
678 53.218 .111 --- 3.029 13.764 .568 32.230 102.921
679 51.936 .106 --- 3.010 13.640 .126 31.422 100.239
680 51.064 .104 --- 3.024 13.648 .022 31.116 98.978
681 51.495 .102 --- 2.965 13.452 .529 31.333 99.877
682 50.468 .105 --- 3.073 13.422 -.240 30.531 97.359
683 52.069 .114 --- 3.034 13.742 .637 31.923 101.519
684 52.480 .094 --- 2.975 13.797 .050 31.692 101.088
685 50.881 .110 --- 3.082 13.601 .442 31.305 99.421
686 52.649 .111 --- 3.023 13.407 -.474 30.973 99.691
687 52.236 .103 --- 2.935 13.714 .332 31.705 101.024
688 54.239 .113 --- 3.010 13.517 -.153 31.761 102.487
AVER: 51.955 .106 --- 3.021 13.619 .102 31.391 100.195
SDEV: .976 .005 --- .046 .130 .364 .462 1.542
SERR: .237 .001 --- .011 .032 .088 .112
%RSD: 1.88 4.87 --- 1.54 .95 356.91 1.47
STDS: 9994 804 --- 818 803 803 ---
STKF: .2674 .3190 --- 1.0000 .1554 .2546 ---
STCT: 1.68 326.01 --- 117.44 9.34 2.50 ---
UNKF: .3147 .0011 --- .0266 .1213 .0007 ---
UNCT: 1.98 1.09 --- 3.12 7.29 .01 ---
UNBG: .24 1.96 --- .27 .15 .74 ---
ZCOR: 1.6508 .9930 --- 1.1368 1.1231 1.3943 ---
KRAW: 1.1772 .0033 --- .0266 .7805 .0029 ---
PKBG: 9.39 1.56 --- 12.74 50.06 1.01 ---
Even though the statistics on the Fe La channel are significantly lower than the Fe Ka channel, I am impressed with how well the two Fe measurements agree with each other. And even more impressive is the deadtime correction on Ben's instrument, because he ran these quite "hot" at 200 nA (and 10 keV)...
Thank-you Ben (and Gareth) for sharing your data with us.
john
Quote from: John Donovan on October 22, 2017, 09:51:28 AM
Even though the statistics on the Fe La channel are significantly lower than the Fe Ka channel, I am impressed with how well the two Fe measurements agree with each other.
Ben Buse tells me that I should not be too impressed with his Fe La data because the unknown sample is the Fe std that was assigned to it. Doh!
But it would be interesting if someone did such a measurement comparing Fe Ln or Ll with Fe Ka on olivines and "toggled" Fe channels on/off to see how well the quantification performs. As Ben reminded me, Xavier Llovet has done some nice work on Fe alloys showing the problem with using Fe La lines for quantification.
john
We recently released an update to Probe for EPMA (and CalcImage and CalcZAF) that contains extensive modifications to the calculation of std k-factors when duplicate elements are being acquired and analyzed. This is version 12.0.3.
http://smf.probesoftware.com/index.php?topic=40.msg6422#msg6422
This is in regards to the "non-physical situation" of a major element being acquired and analyzed on more than one spectrometer. In these situations, the matrix correction will be incorrect due to the totals being significantly over 100% (unless the duplicate elements all utilize the same x-ray line and the Probe for EPMA "aggregate" feature is turned on). However, sometimes it is useful for research purposes to acquire duplicate elements with different x-rays lines for comparisons. In this case, one simply needs to utilize the "disable quant" feature for those duplicate elements that cannot be aggregated because they utilize different x-ray lines (or keVs).
I'm planning on acquiring some real sample data next week on some actual standards, but in the meantime I decided to create a simulation run and check that the calculated std-kfactors (and matrix corrections) on some standards look appropriate. Yes, it's a "circular" test, but if I compare the results from the Standard app (which uses the new "normal sample " std kfac calculation code- since there are no duplicate elements in the Standard database), with the k-factors and matrix corrections from Probe for EPMA (which is using the new duplicate element std kfac calculation code), I can see if the two codes produce the same results and at least know we are internally consistent. ;D
So the simulation run has the following setup:
sp1 PET Au Ma
sp2 LIF Au La
sp3 PET Ag La
sp4 PET Ag La
sp5 LIF Cu ka
But first here are the calculated std kfacs and matrix corrections for one of the NIST Au-Cu-Ag standards at 15 keV and using Au La using the Standard app:
St 680 Au80-Cu20 alloy
TakeOff = 40.0 KiloVolt = 15.0 Density = 15.450 Type = alloy
ELEM: Au Cu
XRAY: la ka
ELWT: 80.150 19.830
KFAC: .7375 .2514
ZCOR: 1.0868 .7889
AT% : 56.597 43.403
Now here is the simulation run in the same standard using the above spectrometer setup when all elements are enabled (the Ag channels are being aggregated because they are using the same x-ray line):
St 680 Set 1 Au80-Cu20 alloy
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 30.0 Beam Size = 0
St 680 Set 1 Au80-Cu20 alloy, Results in Elemental Weight Percents
ELEM: Au Au Ag Ag Cu SUM
XRAY: (ma) (la) (la) (la) (ka)
10 78.179 77.070 .000 .000 19.374 174.622
11 78.203 76.902 -.070 .000 19.490 174.525
12 78.292 76.904 .009 .000 19.528 174.732
AVER: 78.225 76.959 -.021 .000 19.464 174.627
SDEV: .059 .096 .043 .000 .080 .104
SERR: .034 .056 .025 .000 .046
%RSD: .08 .13 -208.64 .0000 .41
PUBL: 80.150 80.150 n.a. n.a. 19.830 99.980
%VAR: -2.40 -3.98 --- --- -1.85
DIFF: -1.925 -3.191 --- --- -.366
STDS: 579 579 547 0 529
STKF: 1.0000 1.0000 .9911 .0000 .9974
UNKF: .7568 .7340 -.0001 .0000 .2537
ZCOR: 1.0336 1.0485 1.4029 .0000 .7671
KRAW: .7568 .7340 -.0001 .0000 .2544
As we can see, the totals are very high because we've added in the Au measurement twice. The matrix correction (ZCOR) is also quite wrong for the same reason). Now let's disable the Au Ma line and look at the Au La line:
St 680 Set 1 Au80-Cu20 alloy
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 30.0 Beam Size = 0
St 680 Set 1 Au80-Cu20 alloy, Results in Elemental Weight Percents
ELEM: Au-D Au Ag Ag Cu SUM
XRAY: (ma) (la) (la) (la) (ka)
10 --- 79.938 .000 .000 19.933 99.870
11 --- 79.781 -.069 .000 20.055 99.768
12 --- 79.790 .008 .000 20.097 99.895
AVER: --- 79.836 -.020 .000 20.028 99.845
SDEV: --- .088 .042 .000 .085 .068
SERR: --- .051 .024 .000 .049
%RSD: --- .11 -208.64 .0000 .42
PUBL: n.a. 80.150 n.a. n.a. 19.830 99.980
%VAR: --- -.39 --- --- 1.00
DIFF: --- -.314 --- --- .198
STDS: --- 579 547 0 529
STKF: --- 1.0000 .9911 .0000 .9974
STCT: --- 330.79 664.67 .00 333.53
UNKF: --- .7340 -.0001 .0000 .2537
ZCOR: --- 1.0877 1.3686 .0000 .7894
KRAW: --- .7340 -.0001 .0000 .2544
As one can see the Au La matrix corrections (ZCOR) in both Standard and PFE, now agree with each other. We can now disable quant for Au La and enable Au Ma, but first the results from the Standard app for the Au Ma line at 15 keV:
St 680 Au80-Cu20 alloy
TakeOff = 40.0 KiloVolt = 15.0 Density = 15.450 Type = alloy
ELEM: Au Cu
XRAY: ma ka
ELWT: 80.150 19.830
KFAC: .7550 .2514
ZCOR: 1.0616 .7889
Now for the results from Probe for EPMA using the Au Ma line:
St 680 Set 1 Au80-Cu20 alloy
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 30.0 Beam Size = 0
St 680 Set 1 Au80-Cu20 alloy, Results in Elemental Weight Percents
ELEM: Au Au-D Ag Ag Cu SUM
XRAY: (ma) (la) (la) (la) (ka)
10 80.314 --- .000 .000 19.928 100.242
11 80.344 --- -.069 .000 20.048 100.324
12 80.435 --- .008 .000 20.088 100.532
AVER: 80.364 --- -.020 .000 20.022 100.366
SDEV: .063 --- .042 .000 .083 .150
SERR: .037 --- .024 .000 .048
%RSD: .08 --- -208.64 .0000 .42
PUBL: 80.150 n.a. n.a. n.a. 19.830 99.980
%VAR: .27 --- --- --- .97
DIFF: .214 --- --- --- .192
STDS: 579 --- 547 0 529
STKF: 1.0000 --- .9911 .0000 .9974
UNKF: .7568 --- -.0001 .0000 .2537
ZCOR: 1.0619 --- 1.3690 .0000 .7891
KRAW: .7568 --- -.0001 .0000 .2544
Again, nice agreement between to two different std kfac codes. Of course we don't have to utilize the pure elements as the primary standards, so here is the same sample but using another NIST alloy (Au60Ag40) as the primary standard for Au:
St 680 Set 1 Au80-Cu20 alloy
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 30.0 Beam Size = 0
St 680 Set 1 Au80-Cu20 alloy, Results in Elemental Weight Percents
ELEM: Au Au-D Ag Ag Cu SUM
XRAY: (ma) (la) (la) (la) (ka)
10 80.324 --- .000 .000 19.928 100.252
11 80.355 --- -.069 .000 20.048 100.334
12 80.446 --- .008 .000 20.088 100.542
AVER: 80.375 --- -.020 .000 20.021 100.376
SDEV: .063 --- .042 .000 .083 .150
SERR: .037 --- .024 .000 .048
%RSD: .08 --- -208.64 .0000 .42
PUBL: 80.150 n.a. n.a. n.a. 19.830 99.980
%VAR: .28 --- --- --- .97
DIFF: .225 --- --- --- .191
STDS: 681 --- 547 0 529
STKF: .5344 --- .9911 .0000 .9974
UNKF: .7569 --- -.0001 .0000 .2537
ZCOR: 1.0619 --- 1.3690 .0000 .7891
KRAW: 1.4162 --- -.0001 .0000 .2544
All this shows of course is that the two std kfac codes agree with each other, but using completely different methods... but internal consistency is a good starting point. I hope to have some real data next week to share.
john
PS I've attached the MDB file below if anyone wants to try some calculations of their own.
Just as a brief follow up to the above post. I wanted to mention that I fixed a minor display issue last night that is related to the situation where one has duplicate elements with different x-ray lines and/or different keVs. But it was an interesting bug because it didn't affect any quantitative results, just the Assign MAN Standards dialog plot. So...
In the case where we have duplicate elements with different x-ray lines or keVs, because we are loading in the concentration of each element one at a time for the std kfactor calculation, if the standard does not contain the element in question, the simply code skipped that std kfactor calculation. After all, why would one ever want to calculate the standard k-factor for an element that is not in the standard? It would be zero or very close to zero. So can you guess?
That's right! It's when that standard is utilized as a standard for the MAN background correction. Remember, a primary standard needs to have a known (major) concentration of the element in question, but an MAN standard needs to have a *zero* concentration of the element in question! After all, it's determining the *background* at the on-peak position, so the element in question must *not* be present in the standards utilized for the MAN bgd calibration for that emission line.
However, the MAN background intensity still needs to be corrected for continuum absorption for each emission line for each MAN standard. And even if the element concentration is zero in an MAN standard (and it had better be!), one still needs to calculate the absorption correction for that emission line in that standard! For samples with no duplicate elements or samples with duplicate elements that have the same x-ray (or keVs), the "normal" std kfactor code worked just fine as all elements are calculated at once. But for the one element at a time calculation (for samples with duplicate elements and different x-ray lines or keVs), we now calculate standard k-factors for all elements in the standard even if the element concentration is zero.
This bug didn't affect any quant analyses because when the MAN bgd calculation is actually applied to a sample analysis, the code utilizes the absorption correction term for the sample (unknown or standard), that is currently being analyzed. It only affected the MAN plot display in the Assign MAN Standards, and only if the sample contained duplicate elements with different x-rays lines and/or keVs.
I thought this was actually a very funny but cute illustration of the difference between normal (primary) standards and MAN standards. Or maybe I'm just a little bit weird with my sense of humor! :D
john