I'm opening this topic with the intent to create a place to discuss improving the Time Dependent Intensity (TDI) correction in Probe for EPMA for beam sensitive sample acquisition. If you want to ask questions or comment on the existing TDI correction please use this topic link here:
http://smf.probesoftware.com/index.php?topic=11.0
The reason for this is that although the TDI correction is PFE works well well for almost all beam sensitive samples (both "volatile" and "grow-in" artifacts as documented by many investigators, such as Stuart Kearns, http://www.geology.wisc.edu/~johnf/g777/AmMin/Humphreys_2006.pdf, and George Morgan, http://www.geology.wisc.edu/~johnf/g777/AmMin/MorganLondon2005.pdf), there are still some situations requiring an even more robust TDI correction due to the limited size of the sample (requiring a more focused beam), or element sensitivity (requiring a higher beam current).
And let's be honest, if we could run these samples at cryogenic temperatures as suggested by Stuart Kearns we could use our existing TDI methods just fine, but almost no one (not even Stuart anymore!), has an EPMA instrument with a cryogenic stage, (Electronprobe Microanalysis of Volcanic Glass at Cryogenic Temperatures (2002) S.L. Kearns,N. Steen and E. Erlund, Microscopy and Microanalysis 8 (Supple 2), 1562-1563CD), so we need a robust software solution that works even under less than ideal conditions.
Please feel free to chime in with your questions, observations and comments. This topic is for all researchers working with beam sensitive materials in EPMA.
Ok, let's start by reviewing what we can do with the Time Dependent Intensity (TDI) correction in Probe for EPMA, which I believe is the best method currently available. By the way, to give credit where credit is due, Paul Carpenter suggested we use the term Time Dependent Intensity, rightly I would say, because then we are not assuming physics we don't fully understand (sample heating, sub-surface charging, ion migration, changes in the matrix absorption due to ion migration, etc.).
Here we see a large but otherwise typical TDI correction (note most of the examples we will discuss will be from Na intensities, but the PFE TDI correction applies equally well to all elements that undergo changes in intensity as a function of beam exposure, e.g., K, Si, Al, F, P, etc.):
(https://smf.probesoftware.com/oldpics/i43.tinypic.com/2qcmaty.jpg)
The above example has a Na TDI correction percent of almost 80%. Not too bad for losing almost half one's Na intensity as seen here:
Un 17 Withers-N5, Results in Elemental Weight Percents
ELEM: Na K Cl Ba F Ti Fe Mn Ca Si Al Mg O H
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL SPEC
BGDS: MAN LIN LIN LIN LIN LOW MAN LIN MAN MAN MAN MAN EXP
TIME: 60.00 20.00 10.00 20.00 40.00 10.00 40.00 10.00 20.00 20.00 20.00 60.00 120.00
BEAM: 9.98 9.98 9.98 9.98 9.98 9.98 9.98 9.98 9.98 9.98 9.98 9.98 9.98
ELEM: Na K Cl Ba F Ti Fe Mn Ca Si Al Mg O H SUM
574 2.780 3.536 .205 .030 .086 .108 3.136 .060 .162 32.680 5.404 .012 50.078 .665 98.943
575 3.072 3.557 .207 .017 .084 .124 3.120 .079 .148 32.990 5.365 .007 49.939 .594 99.303
576 2.846 3.314 .180 .032 .100 .137 3.131 .083 .129 32.914 5.316 .000 49.919 .624 98.727
577 2.925 3.550 .258 .041 .111 .098 3.165 .058 .118 32.858 5.437 -.001 49.985 .621 99.224
578 3.011 3.502 .258 -.014 .083 .072 3.173 .081 .116 32.715 5.364 .009 49.812 .626 98.810
579 3.043 3.561 .239 -.079 .070 .124 3.191 .083 .130 32.812 5.428 .006 50.012 .623 99.244
580 2.842 3.531 .223 .016 .089 .101 3.125 .055 .132 32.799 5.335 -.001 49.969 .644 98.859
581 3.179 3.459 .248 -.019 .121 .118 3.100 .050 .152 33.024 5.362 .006 50.053 .605 99.455
582 2.924 3.505 .164 -.025 .080 .134 3.197 .051 .120 33.124 5.375 .009 49.790 .562 99.009
583 2.890 3.436 .218 -.062 .033 .147 3.165 .031 .143 32.919 5.388 .003 49.908 .609 98.830
584 2.952 3.381 .213 .004 .033 .124 3.124 .064 .133 33.068 5.325 .004 49.852 .588 98.865
585 2.699 3.608 .191 .029 .071 .121 3.150 .061 .161 33.000 5.380 .006 50.223 .641 99.341
AVER: 2.930 3.495 .217 -.003 .080 .117 3.148 .063 .137 32.909 5.373 .005 49.962 .617 99.051
SDEV: .133 .084 .030 .038 .026 .020 .030 .016 .016 .139 .038 .004 .122 .028 .248
SERR: .038 .024 .009 .011 .008 .006 .009 .005 .005 .040 .011 .001 .035 .008
%RSD: 4.54 2.40 13.87-1523.47 33.10 17.21 .97 25.48 11.67 .42 .70 80.01 .24 4.47
STDS: 336 374 285 835 835 22 395 25 358 162 336 12 12 0
STKF: .0735 .1132 .0601 .7430 .1715 .5546 .6779 .7341 .1693 .2018 .1331 .4737 .2328 .0000
STCT: 2447.9 2423.7 839.3 8520.6 2398.7 6097.6 14136.8 13590.2 2247.6 34290.6 23223.7 24410.3 8335.9 .0
UNKF: .0154 .0303 .0017 .0000 .0002 .0010 .0261 .0005 .0012 .2688 .0412 .0000 .2315 .0000
UNCT: 513.0 648.1 24.2 -.2 2.7 10.8 545.2 9.5 16.2 45673.8 7190.2 1.7 8290.2 .0
UNBG: 9.9 12.6 5.0 29.0 3.8 5.8 23.4 16.1 4.4 134.1 103.2 15.2 53.7 .0
ZCOR: 1.9017 1.1548 1.2500 1.3725 4.0763 1.1972 1.2041 1.2234 1.1196 1.2241 1.3036 1.4987 2.1582 .0000
KRAW: .2096 .2674 .0289 .0000 .0011 .0018 .0386 .0007 .0072 1.3320 .3096 .0001 .9945 .0000
PKBG: 52.69 52.56 6.39 1.00 1.77 3.03 24.32 1.61 4.71 341.58 70.64 1.11 156.16 .00
INT%: ---- ---- ---- -3.81 ---- -.02 ---- ---- ---- ---- ---- ---- ---- ----
APF: ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 1.031 ----
TDI%: 79.930 .454 ---- ---- ---- ---- ---- ---- ---- -.870 ---- ---- -3.030 ----
DEV%: 2.7 2.4 ---- ---- ---- ---- ---- ---- ---- .3 ---- ---- .3 ----
TDIF: QUADRA LINEAR ---- ---- ---- ---- ---- ---- ---- LINEAR ---- ---- LINEAR ----
TDIT: 72.58 30.67 ---- ---- ---- ---- ---- ---- ---- 31.00 ---- ---- 129.42 ----
TDII: 522. 660. ---- ---- ---- ---- ---- ---- ---- 45860. ---- ---- 8327. ----
BLNK#: ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 19 ----
BLNKL: ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 43.5580 ----
BLNKV: ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 44.9622 ----
Potassium is much less affected at 0.454 % (not even statistically significant) and silicon and oxygen are minor corrections (-0.87 and -3.03 % respectively, though both statistically significant).
By the way, the above calculation is for water by stoichiometry to measured excess oxygen as first described by Barbara Nash, http://www.geology.wisc.edu/courses/g777/AmMin/Nash.pdf.
Expressed as oxides the results are seen here for this glass made by Tony Withers and water determined by FTIR at 5.06 wt%:
Un 17 Withers-N5, Results in Oxide Weight Percents
ELEM: Na2O K2O Cl BaO F TiO2 FeO MnO CaO SiO2 Al2O3 MgO O H2O SUM
574 3.747 4.260 .205 .033 .086 .180 4.034 .078 .227 69.915 10.212 .019 .000 5.947 98.943
575 4.142 4.284 .207 .018 .084 .207 4.014 .102 .207 70.578 10.138 .011 .000 5.311 99.303
576 3.836 3.992 .180 .036 .100 .229 4.028 .108 .180 70.415 10.045 .001 .000 5.576 98.727
577 3.943 4.276 .258 .046 .111 .164 4.072 .075 .165 70.295 10.274 -.001 .000 5.548 99.224
578 4.059 4.219 .258 -.015 .083 .120 4.082 .105 .163 69.989 10.135 .015 .000 5.597 98.810
579 4.102 4.290 .239 -.088 .070 .207 4.105 .107 .182 70.196 10.257 .009 .000 5.567 99.244
580 3.831 4.253 .223 .018 .089 .169 4.020 .070 .184 70.168 10.080 -.002 .000 5.755 98.859
581 4.285 4.166 .248 -.021 .121 .196 3.988 .064 .213 70.650 10.131 .009 .000 5.405 99.455
582 3.942 4.222 .164 -.028 .080 .224 4.114 .065 .168 70.863 10.155 .014 .000 5.026 99.009
583 3.895 4.139 .218 -.069 .033 .246 4.072 .040 .200 70.426 10.181 .006 .000 5.443 98.830
584 3.980 4.073 .213 .004 .033 .207 4.020 .083 .186 70.744 10.061 .006 .000 5.256 98.865
585 3.638 4.346 .191 .033 .071 .202 4.052 .079 .225 70.599 10.165 .010 .000 5.730 99.341
AVER: 3.950 4.210 .217 -.003 .080 .196 4.050 .081 .192 70.403 10.153 .008 .000 5.513 99.051
SDEV: .179 .101 .030 .043 .026 .034 .039 .021 .022 .298 .071 .007 .000 .247 .248
SERR: .052 .029 .009 .012 .008 .010 .011 .006 .006 .086 .021 .002 .000 .071
%RSD: 4.54 2.40 13.87-1523.47 33.10 17.21 .97 25.48 11.67 .42 .70 80.01 159.54 4.47
STDS: 336 374 285 835 835 22 395 25 358 162 336 12 12 0
Full details of this method are described here:
http://epmalab.uoregon.edu/reports/Withers%20hydrous%20glass.pdf
All this is great, so what's the problem?
Well as mentioned previously, sometimes we have to focus the beam and/or increase the beam current and this can cause a number of additional artifacts. The first I will focus on is the so called "incubation time" described by Stuart Kearns which can be seen in a number of compositions, but the high Na glasses prepared for NIST provides extremely beam sensitive materials that can be useful in these investigations, as we can see here in the low time resolution TDI acquisition on K-0373 NIST glass (10 nA, 10 um):
(https://smf.probesoftware.com/oldpics/i43.tinypic.com/29c9r0l.jpg)
A higher time resolution TDI acquisition will make this artifact even more obvious:
(https://smf.probesoftware.com/oldpics/i40.tinypic.com/2vs146w.jpg)
I suspect that what we are seeing here with this "incubation time" is the warming of the sample by the electron beam. That is to say, ion migration of alkali elements towards the sub surface charge implanted by the electron probe does not start, until the sample spot is heated sufficiently. This hypothesis is further supported by a number of acquisitions where it is observed that it is the first point that almost always shows this "incubation time" effect most strongly. In the previous 10 nA, 20 um beam TDI acquisition it can be seen by displaying all the data points for the sample as seen here:
(https://smf.probesoftware.com/oldpics/i40.tinypic.com/8x8pjb.jpg)
This can also be confirmed by displaying the x and y stage positions of these analyses as seen here:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/2gt0won.jpg)
Note that with a 10 um beam, the 10 um spaced points are essentially adjacent, and therefore the previous point provides a heating time to eliminate sufficient to reduce the "incubation time". Which brings me to a partial solution for this issue.
Clearly if the "incubation time" is variable due to the proximity of previous TDI acquisitions we will have to be more careful about our selection of points for analysis. But if the "incubation time" is fairly reproducible we could utilize a delay in acquisition after the faraday cup is removed, but before the intensity acquisition begins. Interestingly enough, this feature is already built into Probe for EPMA but intended for another application. Called the "Decontamination Time" it was intended to be used for carbon analysis (Pinard and Richter) to allow time for the native hydrocarbon layer on the sample to be removed prior to the count integration as seen here:
(https://smf.probesoftware.com/oldpics/i40.tinypic.com/xn7sef.jpg)
So what's next? Let's examine some other TDI acquisition log slopes more carefully, starting with this acquisition on yet another high Na NIST glass (K-1718) at 10 nA and 10 um, which shows several slopes in exponential space as seen here:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/9vb4vb.jpg)
What's a micro analyst to do?
Oh so back to the problematic issue of slope dermination. The first order approach any salt of the earth spectroscopist would use involves displaying the 1st derivative followed by user interaction by defining the range of time over which the slope is determined.
Breaking out the slope of the earliest/first time dependency mechanism is the most (or only) critical measurement to make as it directly impacts the magnitide of the signal at t=0 unless you are studying the ongoing physics of e- beam-matter interaction itself.
For the materials I have examined such changes take place over relatively short periods of time secs. Hence the challenge is to collect data at short intervals, at the expense of statistics. Once too much time has passed you are potentially either 1)within another of damage regime, or 2) have integrated over an interval so large the slope of the natural log curve is less accurate.
Hi Ed,
I agree completely, especially on the point that we are dealing with several different physical regimes with different time scales, e.g., thermal conductivity vs. ion migration vs. sub surface charge dissapation, but here are my two points (worth one cent each).
1. It is usually better if there is less human subjectivity involved in any analytical procedure. Yes, I could add several user adjustable parameters, but I have found that humans (and I think I can include myself in that group!), have difficulty not adjusting things to the way they want it to be, as opposed to a purely statistical/mathematical decision made by the computer.
So maybe the program should alternately try different fit models until it finds the least average deviation?
What I'm getting at is maybe adding an exponential fit to the existing linear (exponential) and quadratic (hyper-exponential) models, which means in log space we now have a double exponential fit, is worth a try. Such considerations are what this topic is for.
2. The long term (40 or more seconds) TDI acquisition might not only be useful for physics modeling. Maybe it will be possible to back out water vs. hydroxyl based on the slope at different time periods. Yes, I just made that up, but we don't know what we don't know!
Basically I think that I'd like to have the most robust fit available for whatever the data looks like and I agree, it might be that we want to count short TDI intervals to capture the initial intensity at time = 0, but that doesn't mean that we should have to acquire TDI data that way- maybe we have a beam sensitive trace element?
So let's look at where we are on the most beam sensitive material that I have found, the K-1781 NIST glass. Here is an analysis, 10 nA, 10 um *without* any TDI correction:
St 171 Set 9 K-1718 NBS Glass, Results in Elemental Weight Percents
SPEC: O
TYPE: SPEC
AVER: 43.050
SDEV: .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 40.00 40.00 40.00 40.00 40.00
BEAM: 10.58 10.58 10.58 10.58 10.58
ELEM: Na Si Ca Fe P SUM
56 7.849 29.765 4.000 11.140 .008 95.813
57 7.696 30.010 3.958 11.078 -.017 95.775
58 8.004 29.527 3.969 11.224 -.029 95.746
59 7.703 29.477 3.985 11.022 .040 95.277
60 7.822 29.776 3.952 11.185 .044 95.829
AVER: 7.815 29.711 3.973 11.130 .009 95.688
SDEV: .126 .215 .020 .081 .033 .232
SERR: .056 .096 .009 .036 .015
%RSD: 1.61 .72 .50 .73 349.44
PUBL: 14.837 28.048 3.574 10.491 n.a. 100.000
%VAR: -47.33 5.93 11.17 6.09 ---
DIFF: -7.022 1.663 .399 .639 ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 76.73 79.39 602.77 66.49 40.15
UNKF: .0382 .2422 .0367 .0945 .0001
UNCT: 39.89 46.89 61.54 66.11 .02
UNBG: .31 .13 1.04 .98 .06
ZCOR: 2.0450 1.2267 1.0819 1.1776 1.4231
KRAW: .5199 .5906 .1021 .9944 .0004
PKBG: 143.98 389.44 60.42 69.66 .50
Only a -50% error! Now the same measurements with the linear (exponential) TDI fit:
St 171 Set 9 K-1718 NBS Glass, Results in Elemental Weight Percents
SPEC: O
TYPE: SPEC
AVER: 43.050
SDEV: .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 40.00 40.00 40.00 40.00 40.00
BEAM: 10.58 10.58 10.58 10.58 10.58
ELEM: Na Si Ca Fe P SUM
56 17.153 28.107 3.841 11.115 .008 103.273
57 16.928 26.992 3.739 11.054 -.017 101.746
58 17.702 27.520 3.730 11.198 -.029 103.172
59 16.806 27.754 3.718 10.997 .040 102.365
60 17.048 27.434 3.747 11.160 .044 102.484
AVER: 17.128 27.561 3.755 11.105 .009 102.608
SDEV: .346 .411 .049 .081 .033 .628
SERR: .155 .184 .022 .036 .015
%RSD: 2.02 1.49 1.31 .73 348.95
PUBL: 14.837 28.048 3.574 10.491 n.a. 100.000
%VAR: 15.44 -1.73 5.08 5.85 ---
DIFF: 2.291 -.487 .181 .614 ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 78.13 79.81 605.49 66.49 40.15
UNKF: .0875 .2181 .0348 .0945 .0001
UNCT: 93.06 42.45 58.61 66.11 .02
UNBG: .31 .13 1.04 .98 .06
ZCOR: 1.9564 1.2636 1.0786 1.1749 1.4144
KRAW: 1.1911 .5319 .0968 .9944 .0004
PKBG: 335.08 353.48 57.57 69.66 .50
TDI%: 133.257 -9.459 -4.765 ---- ----
DEV%: 7.1 2.7 2.5 ---- ----
TDIF: LINEAR QUADRA LINEAR ---- ----
TDIT: 94.00 94.00 92.80 ---- ----
TDII: 84.3 42.4 59.5 ---- ----
Now only a +15% error. Next we use the quadratic (hyper-exponential) fit:
St 171 Set 9 K-1718 NBS Glass, Results in Elemental Weight Percents
SPEC: O
TYPE: SPEC
AVER: 43.050
SDEV: .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 40.00 40.00 40.00 40.00 40.00
BEAM: 10.58 10.58 10.58 10.58 10.58
ELEM: Na Si Ca Fe P SUM
56 16.267 28.049 3.841 11.117 .008 102.332
57 15.369 26.894 3.739 11.058 -.017 100.093
58 15.942 27.409 3.731 11.203 -.029 101.305
59 15.072 27.641 3.719 11.002 .040 100.523
60 15.408 27.329 3.748 11.164 .044 100.744
AVER: 15.611 27.464 3.756 11.109 .009 100.999
SDEV: .482 .424 .049 .081 .033 .864
SERR: .216 .190 .022 .036 .015
%RSD: 3.09 1.55 1.30 .73 348.95
PUBL: 14.837 28.048 3.574 10.491 n.a. 100.000
%VAR: 5.22 -2.08 5.10 5.89 ---
DIFF: .774 -.584 .182 .618 ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 78.13 79.81 605.49 66.49 40.15
UNKF: .0791 .2181 .0348 .0945 .0001
UNCT: 84.09 42.45 58.61 66.11 .02
UNBG: .31 .13 1.04 .98 .06
ZCOR: 1.9735 1.2591 1.0788 1.1754 1.4140
KRAW: 1.0763 .5319 .0968 .9944 .0004
PKBG: 302.73 353.48 57.57 69.66 .50
TDI%: 110.768 -9.459 -4.765 ---- ----
DEV%: 3.8 2.7 2.5 ---- ----
TDIF: QUADRA QUADRA LINEAR ---- ----
TDIT: 94.00 94.00 92.80 ---- ----
TDII: 84.1 42.4 59.5 ---- ----
Now we have "only" a +5% relative error on Na and this is with a 110% correction to the intensity. Is it perfect? No. Is it better than a poke in the eye with a sharp stick? Yes, and then some.
John,
I understand your point about designing the software with the least fraction of user bias. SO one option would be to compute the instantaneous slope at time steps. E.g. the first 3-4 slopes computed are similar to within X%, you are done and can analyze the material. If however, the values are not simlilar to within that tolerance, expand the number of slopes by some amount to increase the population, if the new SD "converges", you are done. If that value becomes larger then I am not smart enough to recommend an unbiased method for automated analysis and recommend the user intervene as a post collection Analyze! step.
Wow, that is a good idea, though I'm not sure I'm smart enough to code it!
In the meantime, while I think about how your idea might be implemented, here's an option that many might not know about, that I find useful for the very reason we've been discussing (that the first TDI points are the most valuable points for extrapolating to zero time).
Let's start with a normal obsidian glass analysis, this was acquired with Combined Conditions, so the major elements are acquired as a lower beam current (10 nA) than the traces (50 nA) as seen here:
(https://smf.probesoftware.com/oldpics/i43.tinypic.com/ibm3ux.jpg)
Using *no* TDI correction we get these results for quantification:
Un 6 Obsidian trav1
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 2524, Magnification (imaging) = 736)
Image Shift (X,Y): .00, .00
Number of Data Lines: 50 Number of 'Good' Data Lines: 18
First/Last Date-Time: 11/19/2013 05:52:20 PM to 11/20/2013 12:08:21 AM
WARNING- Using Exponential Off-Peak correction for p ka
WARNING- Using Exponential Off-Peak correction for zr la
Average Total Oxygen: 48.564 Average Total Weight%: 97.796
Average Calculated Oxygen: 48.564 Average Atomic Number: 11.176
Average Excess Oxygen: .000 Average Atomic Weight: 20.541
Oxygen Equiv. from Halogen: .008 Halogen Corrected Oxygen: 48.555
Average ZAF Iteration: 3.00 Average Quant Iterate: 4.00
Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction
Oxygen Equivalent from Halogens (F/Cl/Br/I), Not Subtracted in the Matrix Correction
Combined Analytical Condition Arrays:
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr
TAKE: 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0
KILO: 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0
CURR: 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 50.0 50.0 50.0 50.0 50.0
SIZE: 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0
Un 6 Obsidian trav1, Results in Elemental Weight Percents
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL CALC SPEC
BGDS: MAN MAN LIN MAN MAN MAN MAN LIN LIN LIN LIN LIN EXP EXP
TIME: 90.00 60.00 20.00 80.00 60.00 160.00 80.00 40.00 30.00 100.00 100.00 100.00 100.00 100.00
BEAM: 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 50.29 50.29 50.29 50.29 50.29
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H SUM
178 1.770 35.590 3.816 7.044 .024 .511 .356 .060 .071 .002 .044 .036 .001 -.010 48.570 .000 97.884
179 1.762 35.561 3.809 7.033 .016 .501 .351 .007 .048 .003 .046 .046 -.004 -.011 48.496 .000 97.663
180 1.775 35.653 3.788 7.074 .017 .443 .364 .016 .046 .003 .042 .028 -.004 .006 48.622 .000 97.872
181 1.815 35.576 3.802 6.993 .017 .471 .362 .032 .055 -.001 .039 .050 -.003 -.009 48.503 .000 97.703
182 1.809 35.728 3.724 7.057 .021 .496 .369 -.021 .053 -.001 .041 .027 .000 -.008 48.706 .000 98.001
183 1.829 35.621 3.802 7.019 .022 .465 .371 -.003 .058 -.001 .040 .037 -.003 -.006 48.573 .000 97.824
184 1.855 35.658 3.775 7.054 .019 .516 .358 -.006 .064 .002 .035 .038 -.003 .001 48.662 .000 98.028
185 1.861 35.641 3.807 6.993 .023 .493 .365 -.009 .040 .002 .036 .020 -.001 -.020 48.573 .000 97.825
186 1.826 35.627 3.804 7.037 .024 .466 .363 -.017 .039 .001 .033 .037 .000 .000 48.594 .000 97.836
187 1.831 35.592 3.831 6.959 .023 .462 .354 .040 .033 .000 .036 .042 -.005 -.010 48.487 .000 97.674
188 1.829 35.573 3.765 7.059 .016 .403 .351 .031 .040 .001 .034 .023 .000 -.002 48.514 .000 97.637
189 1.855 35.602 3.849 7.017 .019 .386 .355 .007 .029 .001 .033 .030 .003 -.006 48.534 .000 97.715
190 1.861 35.704 3.837 7.054 .016 .426 .343 .032 .042 .002 .033 .027 -.006 -.015 48.680 .000 98.037
191 1.832 35.588 3.759 7.006 .019 .439 .352 .001 .047 -.002 .034 .039 -.002 -.020 48.494 .000 97.586
192 1.842 35.558 3.805 7.003 .018 .460 .361 .037 .064 -.001 .034 .034 -.001 -.006 48.494 .000 97.703
193 1.876 35.672 3.773 6.995 .019 .476 .366 .032 .051 .000 .034 .031 .000 -.012 48.623 .000 97.937
194 1.789 35.682 3.836 7.001 .019 .465 .351 -.013 .055 -.001 .035 .020 -.002 -.008 48.596 .000 97.825
195 1.865 35.482 3.772 7.013 .016 .471 .352 .065 .040 .000 .035 .049 .004 -.018 48.427 .000 97.573
AVER: 1.827 35.617 3.797 7.023 .019 .464 .358 .016 .049 .001 .037 .034 -.001 -.009 48.564 .000 97.796
SDEV: .035 .060 .032 .030 .003 .035 .008 .026 .011 .002 .004 .009 .003 .007 .076 .000 .147
SERR: .008 .014 .008 .007 .001 .008 .002 .006 .003 .000 .001 .002 .001 .002 .018 .000
%RSD: 1.89 .17 .84 .43 14.75 7.53 2.11 161.28 23.09 265.87 10.91 26.42 -199.09 -82.48 .16 .00
STDS: 336 14 374 160 162 162 162 251 25 730 285 22 285 257 0 0
STKF: .0735 .4101 .1132 .0334 .0568 .0950 .1027 .4268 .7341 .5061 .0601 .5547 .1599 .4201 .0000 .0000
STCT: 71.42 566.01 224.55 62.55 81.21 18.31 161.20 292.31 2053.05 449.51 79.86 58.15 227.12 213.15 .00 .00
UNKF: .0100 .2943 .0329 .0559 .0001 .0039 .0032 .0001 .0004 .0000 .0003 .0003 .0000 -.0001 .0000 .0000
UNCT: 9.75 406.17 65.30 104.57 .19 .75 5.02 .09 1.12 .00 .39 .03 -.01 -.03 .00 .00
UNBG: .32 .22 .94 .89 .52 .23 1.01 .94 4.78 .16 .33 .05 .81 .88 .00 .00
ZCOR: 1.8208 1.2103 1.1537 1.2567 1.4293 1.1985 1.1194 1.2284 1.2180 1.2872 1.2540 1.1978 1.4649 1.4613 .0000 .0000
KRAW: .1365 .7176 .2908 1.6717 .0024 .0407 .0312 .0003 .0005 .0000 .0049 .0005 -.0001 -.0001 .0000 .0000
PKBG: 31.48 1852.73 70.81 118.92 1.37 4.30 5.97 1.11 1.24 1.03 2.20 1.65 .98 .97 .00 .00
INT%: ---- ---- ---- ---- ---- -.01 ---- -94.80 ---- ---- ---- ---- ---- ---- ---- ----
Obviously the totals are low, so we might suspect a TDI situation (even though we used a 10 um beam for all the points). If we examine the TDI data (I almost always just leave this acquisition option turned on because it uses very little overhead, and if you do run into a TDI situation you already have the intensity interval data to perform a TDI correction), you'll see a significant decrease in the Na intensities over time as seen here:
(https://smf.probesoftware.com/oldpics/i41.tinypic.com/msf0g7.jpg)
For Si ka the situation is less dire (and is barely statistically significant), but worth a correction:
(https://smf.probesoftware.com/oldpics/i41.tinypic.com/5vu4up.jpg)
Al ka is somewhat more statistically significant as seen here:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/2wrhpbb.jpg)
The results for these linear (exponential) extrapolations are seen here:
Un 6 Obsidian trav1, Results in Elemental Weight Percents
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL CALC SPEC
BGDS: MAN MAN LIN MAN MAN MAN MAN LIN LIN LIN LIN LIN EXP EXP
TIME: 90.00 60.00 20.00 80.00 60.00 160.00 80.00 40.00 30.00 100.00 100.00 100.00 100.00 100.00
BEAM: 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 50.29 50.29 50.29 50.29 50.29
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H SUM
178 3.458 35.730 3.773 7.123 .025 .509 .356 .061 .071 .002 .044 .036 .001 -.010 49.379 .000 100.556
179 3.582 35.538 3.941 6.956 .017 .467 .351 .008 .048 .003 .046 .045 -.004 -.011 49.052 .000 100.038
180 3.500 35.492 3.746 6.986 .019 .428 .364 .018 .046 .003 .042 .028 -.004 .006 48.949 .000 99.621
181 3.414 35.456 3.844 6.899 .018 .454 .362 .034 .055 -.001 .039 .050 -.003 -.009 48.843 .000 99.455
182 3.611 35.556 3.657 7.047 .022 .476 .369 -.018 .053 -.001 .041 .027 .000 -.008 49.110 .000 99.943
183 3.451 35.456 3.873 7.107 .023 .487 .371 .000 .058 -.001 .040 .037 -.003 -.006 49.050 .000 99.944
184 3.550 35.447 3.738 6.971 .020 .501 .358 -.003 .064 .002 .035 .038 -.003 .001 48.927 .000 99.646
185 3.516 35.604 3.797 6.893 .024 .414 .365 -.008 .040 .002 .036 .020 -.001 -.020 48.993 .000 99.676
186 3.600 35.384 3.810 7.045 .026 .428 .363 -.014 .039 .001 .033 .037 .000 .000 48.933 .000 99.685
187 3.442 35.291 3.888 6.912 .024 .454 .354 .044 .033 .000 .036 .042 -.005 -.010 48.673 .000 99.178
188 3.502 35.386 3.720 7.048 .017 .406 .351 .033 .040 .001 .034 .023 .000 -.002 48.865 .000 99.424
189 3.609 35.398 3.754 7.058 .020 .376 .355 .010 .029 .001 .033 .030 .003 -.006 48.927 .000 99.596
190 3.459 35.330 3.871 7.052 .018 .453 .343 .036 .042 .002 .033 .027 -.006 -.015 48.824 .000 99.469
191 3.454 35.410 3.676 6.966 .020 .477 .351 .004 .047 -.002 .034 .039 -.002 -.020 48.815 .000 99.269
192 3.526 35.369 3.813 6.985 .020 .488 .360 .040 .063 -.001 .034 .034 -.001 -.006 48.860 .000 99.586
193 3.650 35.608 3.663 7.046 .021 .452 .366 .034 .051 .000 .034 .031 .000 -.012 49.184 .000 100.128
194 3.528 35.638 3.694 7.110 .020 .512 .351 -.011 .055 -.001 .035 .020 -.002 -.008 49.234 .000 100.175
195 3.533 35.369 3.739 7.109 .017 .472 .352 .067 .040 .000 .035 .049 .004 -.018 48.959 .000 99.728
AVER: 3.521 35.470 3.778 7.017 .021 .459 .358 .018 .049 .001 .037 .034 -.001 -.009 48.977 .000 99.729
SDEV: .068 .119 .083 .074 .003 .037 .008 .026 .011 .002 .004 .009 .003 .007 .170 .000 .347
SERR: .016 .028 .020 .017 .001 .009 .002 .006 .003 .000 .001 .002 .001 .002 .040 .000
%RSD: 1.94 .34 2.19 1.06 14.11 8.09 2.12 140.65 23.09 265.87 10.91 26.43 -199.11 -82.49 .35 .00
STDS: 336 14 374 160 162 162 162 251 25 730 285 22 285 257 0 0
STKF: .0735 .4101 .1132 .0334 .0568 .0950 .1027 .4268 .7341 .5061 .0601 .5547 .1599 .4201 .0000 .0000
STCT: 70.51 567.11 225.51 62.06 81.21 18.46 161.20 292.31 2053.05 449.51 79.86 58.15 227.12 213.15 .00 .00
UNKF: .0195 .2914 .0328 .0552 .0001 .0038 .0032 .0001 .0004 .0000 .0003 .0003 .0000 -.0001 .0000 .0000
UNCT: 18.68 403.03 65.30 102.52 .20 .74 5.02 .10 1.12 .00 .39 .03 -.01 -.03 .00 .00
UNBG: .32 .22 .94 .88 .51 .23 1.01 .94 4.78 .16 .33 .05 .81 .88 .00 .00
ZCOR: 1.8086 1.2170 1.1526 1.2706 1.4508 1.1979 1.1182 1.2346 1.2173 1.2854 1.2525 1.1969 1.4626 1.4590 .0000 .0000
KRAW: .2649 .7107 .2896 1.6521 .0025 .0403 .0312 .0004 .0005 .0000 .0049 .0005 -.0001 -.0001 .0000 .0000
PKBG: 59.19 1852.27 70.83 117.93 1.40 4.30 5.98 1.12 1.24 1.03 2.20 1.65 .98 .97 .00 .00
INT%: ---- ---- ---- ---- ---- -.02 ---- -93.93 ---- ---- ---- ---- ---- ---- ---- ----
TDI%: 88.751 -.772 -.008 -1.945 ---- -.173 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
DEV%: 5.8 .7 2.8 1.2 ---- 8.4 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDIF: LINEAR LINEAR LINEAR LINEAR ---- LINEAR ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDIT: 125.56 97.78 61.11 117.28 ---- 198.17 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDII: 18.5 403. 66.2 103. ---- .963 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
The totals look good, but are we done? Well if we look more closely at the Na TDI plot above, we see that there seems to be a slight curvature in the linear (exponential) fit, so maybe we should utilize the quadratic fit in log space or "hyper-exponential" fit as seen here:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/29dxq38.jpg)
How does this tiny change affect our results? Not that much, but a little. Note the difference in the average deviation in the linear and quadratic fits for Na. The linear (conventional exponential fit) has a DEV% of 5.8, while the "hyper-exponential" (quadratic exponential fit) has a DEV% of 3.4, so the hyper-exponential is definitetely a better fit to the data as seen here:
Un 6 Obsidian trav1, Results in Elemental Weight Percents
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL CALC SPEC
BGDS: MAN MAN LIN MAN MAN MAN MAN LIN LIN LIN LIN LIN EXP EXP
TIME: 90.00 60.00 20.00 80.00 60.00 160.00 80.00 40.00 30.00 100.00 100.00 100.00 100.00 100.00
BEAM: 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 50.29 50.29 50.29 50.29 50.29
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H SUM
178 3.348 35.718 3.773 7.118 .025 .509 .356 .061 .071 .002 .044 .036 .001 -.010 49.322 .000 100.373
179 3.491 35.527 3.941 6.952 .017 .467 .351 .008 .048 .003 .046 .045 -.004 -.011 49.004 .000 99.885
180 3.286 35.467 3.747 6.976 .018 .428 .364 .018 .046 .003 .042 .028 -.004 .006 48.838 .000 99.264
181 3.284 35.442 3.844 6.893 .018 .454 .362 .034 .055 -.001 .039 .050 -.003 -.009 48.776 .000 99.238
182 3.335 35.524 3.658 7.035 .022 .476 .369 -.018 .053 -.001 .041 .027 .000 -.008 48.967 .000 99.481
183 3.360 35.446 3.873 7.103 .023 .487 .371 .000 .058 -.001 .040 .037 -.003 -.006 49.003 .000 99.790
184 3.379 35.427 3.739 6.964 .020 .501 .358 -.003 .064 .002 .035 .038 -.003 .001 48.839 .000 99.361
185 3.540 35.606 3.797 6.895 .024 .414 .365 -.008 .040 .002 .036 .020 -.001 -.020 49.006 .000 99.717
186 3.517 35.375 3.810 7.041 .026 .428 .363 -.014 .039 .001 .033 .037 .000 .000 48.890 .000 99.545
187 3.432 35.290 3.888 6.912 .024 .454 .354 .044 .033 .000 .036 .042 -.005 -.010 48.668 .000 99.161
188 3.320 35.365 3.720 7.040 .017 .406 .351 .033 .040 .001 .034 .023 .000 -.002 48.771 .000 99.118
189 3.309 35.364 3.754 7.044 .020 .376 .355 .010 .029 .001 .033 .030 .003 -.006 48.772 .000 99.094
190 3.479 35.332 3.871 7.053 .018 .453 .343 .036 .042 .002 .033 .027 -.006 -.015 48.834 .000 99.501
191 3.412 35.405 3.676 6.964 .020 .477 .351 .004 .047 -.002 .034 .039 -.002 -.020 48.793 .000 99.198
192 3.431 35.358 3.813 6.981 .019 .488 .360 .040 .063 -.001 .034 .034 -.001 -.006 48.811 .000 99.427
193 3.423 35.582 3.663 7.036 .020 .452 .366 .034 .051 .000 .034 .031 .000 -.012 49.066 .000 99.747
194 3.390 35.623 3.695 7.104 .020 .512 .351 -.011 .055 -.001 .035 .020 -.002 -.008 49.163 .000 99.944
195 3.324 35.346 3.740 7.099 .017 .472 .352 .067 .040 .000 .035 .049 .004 -.018 48.851 .000 99.379
AVER: 3.392 35.455 3.778 7.012 .020 .459 .358 .019 .049 .001 .037 .034 -.001 -.009 48.910 .000 99.512
SDEV: .079 .118 .083 .073 .003 .037 .008 .026 .011 .002 .004 .009 .003 .007 .162 .000 .341
SERR: .019 .028 .019 .017 .001 .009 .002 .006 .003 .000 .001 .002 .001 .002 .038 .000
%RSD: 2.32 .33 2.19 1.03 14.25 8.09 2.12 140.57 23.09 265.88 10.91 26.43 -199.12 -82.46 .33 .00
STDS: 336 14 374 160 162 162 162 251 25 730 285 22 285 257 0 0
STKF: .0735 .4101 .1132 .0334 .0568 .0950 .1027 .4268 .7341 .5061 .0601 .5547 .1599 .4201 .0000 .0000
STCT: 70.51 567.11 225.51 62.06 81.21 18.46 161.20 292.31 2053.05 449.51 79.86 58.15 227.12 213.15 .00 .00
UNKF: .0187 .2914 .0328 .0552 .0001 .0038 .0032 .0001 .0004 .0000 .0003 .0003 .0000 -.0001 .0000 .0000
UNCT: 17.98 403.03 65.30 102.52 .20 .74 5.02 .10 1.12 .00 .39 .03 -.01 -.03 .00 .00
UNBG: .32 .22 .94 .88 .51 .23 1.01 .94 4.78 .16 .33 .05 .81 .88 .00 .00
ZCOR: 1.8095 1.2165 1.1527 1.2696 1.4493 1.1979 1.1183 1.2342 1.2174 1.2855 1.2526 1.1969 1.4627 1.4597 .0000 .0000
KRAW: .2550 .7107 .2896 1.6521 .0025 .0403 .0312 .0004 .0005 .0000 .0049 .0005 -.0001 -.0001 .0000 .0000
PKBG: 57.04 1851.22 70.83 117.83 1.39 4.30 5.97 1.12 1.24 1.03 2.20 1.65 .98 .97 .00 .00
INT%: ---- ---- ---- ---- ---- -.02 ---- -93.93 ---- ---- ---- ---- ---- ---- ---- ----
TDI%: 81.846 -.772 -.008 -1.945 ---- -.173 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
DEV%: 3.4 .7 2.8 1.2 ---- 8.4 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDIF: QUADRA LINEAR LINEAR LINEAR ---- LINEAR ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDIT: 125.56 97.78 61.11 117.28 ---- 198.17 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDII: 18.3 403. 66.2 103. ---- .963 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
And our Na value went from 3.5 wt% to just under 3.4 wt%. Not much, remember the fit is better, so it should be a better extrapolation.
Now what about Ed's point about the early TDI intervals being more important for the extrapolation?
If we pull up the Analytical | Analysis Options menu dialog, in addition to a global flag for toggling all TDI corrections in the run, we also see the Use Time Weighted data for TFI Fit option. Let's turn that on and use the default 8 weighting factor which means that the first TDI point will be duplicated 8 times, the 2nd TDI point 7 times, the 3rd TDI point 6 times, etc., etc., before being fit!
(https://smf.probesoftware.com/oldpics/i43.tinypic.com/2pt3pk1.jpg)
Now what does our Na data look like?
Un 6 Obsidian trav1, Results in Elemental Weight Percents
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL CALC SPEC
BGDS: MAN MAN LIN MAN MAN MAN MAN LIN LIN LIN LIN LIN EXP EXP
TIME: 90.00 60.00 20.00 80.00 60.00 160.00 80.00 40.00 30.00 100.00 100.00 100.00 100.00 100.00
BEAM: 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 9.99 50.29 50.29 50.29 50.29 50.29
ELEM: Na Si K Al Mg Fe Ca Sr Mn S Cl Ti P Zr O H SUM
178 3.086 35.654 3.801 7.090 .025 .497 .356 .061 .071 .002 .044 .036 .001 -.010 49.135 .000 99.848
179 3.321 35.488 3.953 6.886 .017 .483 .351 .008 .048 .003 .046 .045 -.004 -.011 48.849 .000 99.483
180 3.273 35.258 3.674 7.076 .018 .417 .364 .020 .046 .003 .042 .028 -.004 .006 48.666 .000 98.887
181 3.121 35.403 3.897 6.847 .018 .480 .362 .034 .055 -.001 .039 .050 -.003 -.009 48.652 .000 98.946
182 3.300 35.628 3.621 6.982 .022 .534 .369 -.019 .053 -.001 .041 .027 .000 -.008 49.035 .000 99.584
183 3.354 35.546 3.822 7.081 .023 .494 .371 -.001 .058 -.001 .040 .037 -.003 -.006 49.088 .000 99.904
184 3.277 35.309 3.695 6.935 .020 .471 .358 -.003 .064 .002 .035 .038 -.003 .001 48.626 .000 98.824
185 3.450 35.538 3.764 6.835 .024 .418 .365 -.008 .040 .002 .036 .020 -.001 -.020 48.838 .000 99.302
186 3.465 35.431 3.717 7.048 .026 .441 .363 -.015 .039 .001 .033 .037 .000 .000 48.925 .000 99.510
187 3.366 35.184 3.895 6.827 .024 .475 .354 .044 .033 .000 .036 .042 -.005 -.010 48.456 .000 98.721
188 3.155 35.356 3.740 6.979 .016 .392 .351 .033 .040 .001 .034 .023 .000 -.002 48.649 .000 98.768
189 3.186 35.214 3.775 7.030 .020 .372 .355 .011 .029 .001 .033 .030 .003 -.006 48.549 .000 98.601
190 3.365 35.294 3.854 7.085 .017 .473 .343 .036 .042 .002 .033 .027 -.006 -.015 48.783 .000 99.335
191 3.305 35.340 3.648 6.952 .020 .475 .351 .004 .047 -.002 .034 .039 -.002 -.020 48.664 .000 98.854
192 3.403 35.474 3.750 6.899 .019 .460 .360 .039 .063 -.001 .034 .034 -.001 -.006 48.840 .000 99.371
193 3.304 35.654 3.683 7.005 .020 .446 .366 .033 .051 .000 .034 .031 .000 -.012 49.082 .000 99.699
194 3.209 35.320 3.662 7.111 .020 .539 .351 -.009 .055 -.001 .035 .020 -.002 -.008 48.762 .000 99.064
195 3.181 35.328 3.741 7.089 .017 .476 .352 .067 .040 .000 .035 .049 .004 -.018 48.774 .000 99.136
AVER: 3.284 35.412 3.761 6.987 .020 .464 .358 .019 .049 .001 .037 .034 -.001 -.009 48.798 .000 99.213
SDEV: .110 .148 .094 .097 .003 .044 .008 .026 .011 .002 .004 .009 .003 .007 .195 .000 .403
SERR: .026 .035 .022 .023 .001 .010 .002 .006 .003 .000 .001 .002 .001 .002 .046 .000
%RSD: 3.33 .42 2.50 1.38 14.35 9.44 2.12 138.43 23.09 265.87 10.91 26.43 -199.12 -82.49 .40 .00
STDS: 336 14 374 160 162 162 162 251 25 730 285 22 285 257 0 0
STKF: .0735 .4101 .1132 .0334 .0568 .0950 .1027 .4268 .7341 .5061 .0601 .5547 .1599 .4201 .0000 .0000
STCT: 71.55 568.51 226.21 62.09 81.21 18.33 161.20 292.31 2053.05 449.51 79.86 58.15 227.12 213.15 .00 .00
UNKF: .0181 .2912 .0326 .0551 .0001 .0039 .0032 .0002 .0004 .0000 .0003 .0003 .0000 -.0001 .0000 .0000
UNCT: 17.66 403.69 65.20 102.27 .20 .75 5.02 .10 1.12 .00 .39 .03 -.01 -.03 .00 .00
UNBG: .32 .22 .94 .88 .51 .23 1.01 .94 4.78 .16 .33 .05 .81 .88 .00 .00
ZCOR: 1.8103 1.2161 1.1528 1.2688 1.4481 1.1980 1.1184 1.2337 1.2174 1.2857 1.2528 1.1970 1.4629 1.4594 .0000 .0000
KRAW: .2468 .7101 .2882 1.6472 .0025 .0407 .0312 .0004 .0005 .0000 .0049 .0005 -.0001 -.0001 .0000 .0000
PKBG: 56.05 1853.28 70.71 117.47 1.39 4.31 5.97 1.12 1.24 1.03 2.20 1.65 .98 .97 .00 .00
INT%: ---- ---- ---- ---- ---- -.02 ---- -93.84 ---- ---- ---- ---- ---- ---- ---- ----
TDI%: 78.615 -.609 -.162 -2.187 ---- .092 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
DEV%: 2.5 .7 2.5 1.2 ---- 7.6 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDIF: QUADRA LINEAR LINEAR LINEAR ---- LINEAR ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDIT: 125.56 97.78 61.11 117.28 ---- 198.17 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
TDII: 18.0 404. 66.1 103. ---- .965 ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
I have to say I was surprised. The time weighted data option had more effect on the data that the hyper-exponential fit (on this dataset anyway), because Na went from 3.4 wt% to 3.28 wt% *and* the overall DEV% improved to 2.5.
So, yes, Ed is correct, we should give our first TDI intervals more "weight" one way or another.
And now for something completely different! ;D
A student recently analyzed a fiber optic as a class project and it was interesting to see the TDI effects for pure SiO2 crystal versus glass. For example, if we use SiO2 as a standard and acquire the standard also as an unknown, we get reasonable results because the TDI effects on the Si Ka and O ka are almost normalized out as seen here:
Un 7 SiO2 synthetic
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 50.0 Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 11/27/2013 04:57:01 PM to 11/27/2013 05:21:02 PM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for o ka
Average Total Oxygen: .000 Average Total Weight%: 99.708
Average Calculated Oxygen: .000 Average Atomic Number: 10.798
Average Excess Oxygen: .000 Average Atomic Weight: 20.020
Oxygen Equiv. from Halogen: .000 Halogen Corrected Oxygen: .000
Average ZAF Iteration: 7.00 Average Quant Iterate: 2.00
Un 7 SiO2 synthetic, Results in Elemental Weight Percents
ELEM: Si O Er Cl
BGDS: EXP EXP LIN LIN
TIME: 40.00 40.00 160.00 160.00
BEAM: 50.09 50.09 50.09 50.09
ELEM: Si O Er Cl SUM
169 46.586 53.121 -.001 -.001 99.705
170 46.491 53.288 -.002 .001 99.777
171 46.521 53.079 .008 .000 99.607
172 46.599 53.152 -.009 .002 99.745
173 46.459 53.260 -.013 .000 99.706
AVER: 46.531 53.180 -.003 .000 99.708
SDEV: .060 .090 .008 .001 .064
SERR: .027 .040 .004 .001
%RSD: .13 .17 -235.67 745.15
STDS: 14 14 1003 285
STKF: .4101 .2664 .5350 .0601
STCT: 693.09 267.64 184.31 43.90
UNKF: .4082 .2661 .0000 .0000
UNCT: 689.96 267.40 -.01 .00
UNBG: 1.00 1.44 .82 .22
ZCOR: 1.1398 1.9985 1.5611 1.2798
KRAW: .9955 .9991 .0000 .0000
PKBG: 692.47 186.37 .99 1.01
In addition to the TDI effects being similar (because we are analyzing the same material for both standard and unknown), they are also fairly minor in magnitude as seen here for Si Ka in SiO2 crystal:
(https://smf.probesoftware.com/oldpics/i43.tinypic.com/5ww4kn.jpg)
One could even argue we are "over fitting" the Si Ka TDI correction because it is such a small correction. Which is *not* the case for O Ka in SiO2 crystal:
(https://smf.probesoftware.com/oldpics/i40.tinypic.com/28cegid.jpg)
As has been observed by many, the oxygen intensity changes dramatically over time even with a 10 um diameter beam. In fact the TDI effect for O Ka is very dependent on subtle surface conditions such as the carbon coat. Because of this, with the TDI correction turned on for both the standard SiO2 and the same standard acquired as an unknown, we get these somewhat improved results for SiO2 analyzed as an unknown:
Un 7 SiO2 synthetic
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 50.0 Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 11/27/2013 04:57:01 PM to 11/27/2013 05:21:02 PM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for o ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
Average Total Oxygen: .000 Average Total Weight%: 99.846
Average Calculated Oxygen: .000 Average Atomic Number: 10.800
Average Excess Oxygen: .000 Average Atomic Weight: 20.024
Oxygen Equiv. from Halogen: .000 Halogen Corrected Oxygen: .000
Average ZAF Iteration: 7.00 Average Quant Iterate: 2.00
Un 7 SiO2 synthetic, Results in Elemental Weight Percents
ELEM: Si O Er Cl
BGDS: EXP EXP LIN LIN
TIME: 40.00 40.00 160.00 160.00
BEAM: 50.09 50.09 50.09 50.09
ELEM: Si O Er Cl SUM
169 46.629 53.392 -.001 -.001 100.019
170 46.641 53.254 -.002 .001 99.893
171 46.414 53.376 .007 .000 99.797
172 46.619 52.784 -.009 .002 99.397
173 46.856 53.279 -.013 .000 100.122
AVER: 46.632 53.217 -.003 .000 99.846
SDEV: .157 .249 .008 .001 .280
SERR: .070 .111 .004 .001
%RSD: .34 .47 -230.82 747.92
STDS: 14 14 1003 285
STKF: .4101 .2664 .5350 .0601
STCT: 699.38 249.93 184.41 50.55
UNKF: .4092 .2662 .0000 .0000
UNCT: 697.79 249.77 -.01 .00
UNBG: 1.00 1.44 .82 .22
ZCOR: 1.1397 1.9993 1.5466 1.2799
KRAW: .9977 .9993 .0000 .0000
PKBG: 700.33 174.14 .99 1.01
TDI%: 1.135 -6.591 -.632 -.248
DEV%: .1 .2 .2 1.3
TDIF: QUADRA QUADRA LINEAR LINEAR
TDIT: 51.40 51.80 170.20 170.20
TDII: 698. 250. .823 .220
From this we might conclude that even when analyzing the *same* material, it is sometimes necessary to run *both* the standard and unknown not only at similar beam conditions, but also utilizing the TDI acquisition and correction for both standard and unknown because of subtle variations in coating, adsorbed water, beam focus and thermal conductivity (etc.?).
Ok, so I was able to do a quick run of SiO2 crystal versus SiO2 glass and here are the results. Conditions (using the Analyze! "Report" button) were:
Compositional analyses were acquired on an electron microprobe (Cameca SX100 (TCP/IP Socket)) equipped with 5 tunable wavelength dispersive spectrometers. Operating conditions were 40 degrees takeoff angle, and a beam energy of 15 keV. The beam current was 50 nA, and the beam diameter was 10 microns.
Elements were acquired using analyzing crystals LPET for Cl ka, LTAP for Al ka, TAP for Si ka, and PC1 for O ka.
The standards were Ca10(PO4)6Cl2 (halogen corrected) for Cl ka, Nepheline (partial anal.) for Al ka, and SiO2 (elemental) (#14) for Si ka, O ka.
The counting time was 60 seconds for all elements. The intensity data was corrected for Time Dependent Intensity (TDI) loss (or gain) using a self calibrated correction for Si ka, O ka, Al ka, Cl ka. The off peak counting time was 20 seconds for all elements. Off Peak correction method was Linear for Cl ka, and Exponential for O ka, Al ka, Si ka.
Unknown and standard intensities were corrected for deadtime. Standard intensities were corrected for standard drift over time.
The exponential or polynomial background fit was utilized. See John J. Donovan, Heather A. Lowers and Brian G. Rusk, Improved electron probe microanalysis of trace elements in quartz, American Mineralogist, 96, 2011
The SiO2 crystal acquisition for Si Ka looks like this:
(https://smf.probesoftware.com/oldpics/i44.tinypic.com/win2wm.jpg)
The SiO2 crystal acquisition for O Ka looks like this:
(https://smf.probesoftware.com/oldpics/i41.tinypic.com/2zrnrrn.jpg)
The SiO2 glass acquisition for Si Ka looks like this:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/2w74pp3.jpg)
The SiO2 glass acquisition for O Ka looks like this:
(https://smf.probesoftware.com/oldpics/i40.tinypic.com/2ah76dh.jpg)
The quant results running both materials as unknowns (using SiO2 crystal as the primary standard) is here w/o the TDI correction:
Un 2 SiO2 xtal
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 50.0 Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 12/03/2013 02:48:14 PM to 12/03/2013 02:57:40 PM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for o ka
WARNING- Using Exponential Off-Peak correction for al ka
Average Total Oxygen: .000 Average Total Weight%: 100.309
Average Calculated Oxygen: .000 Average Atomic Number: 10.799
Average Excess Oxygen: .000 Average Atomic Weight: 20.019
Oxygen Equiv. from Halogen: .000 Halogen Corrected Oxygen: .000
Average ZAF Iteration: 7.00 Average Quant Iterate: 2.00
Un 2 SiO2 xtal, Results in Elemental Weight Percents
ELEM: Si O Al Cl
BGDS: EXP EXP EXP LIN
TIME: 60.00 60.00 60.00 60.00
BEAM: 49.82 49.82 49.82 49.82
ELEM: Si O Al Cl SUM
117 46.791 53.450 .005 .001 100.247
118 46.767 53.493 .000 .000 100.259
119 46.849 53.574 .001 .000 100.425
120 46.774 53.489 .000 .003 100.266
121 46.785 53.559 .005 .001 100.350
AVER: 46.793 53.513 .002 .001 100.309
SDEV: .033 .052 .003 .001 .076
SERR: .015 .023 .001 .001
%RSD: .07 .10 121.62 104.43
STDS: 914 914 336 285
STKF: .4101 .2664 .1331 .0601
STCT: 687.69 250.10 724.87 78.57
UNKF: .4105 .2678 .0000 .0000
UNCT: 688.37 251.44 .10 .01
UNBG: .98 1.38 3.19 .32
ZCOR: 1.1399 1.9982 1.2289 1.2798
KRAW: 1.0010 1.0053 .0001 .0002
PKBG: 704.90 183.81 1.03 1.04
Un 3 SiO2 glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 50.0 Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 12/03/2013 03:00:25 PM to 12/03/2013 03:09:47 PM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for o ka
WARNING- Using Exponential Off-Peak correction for al ka
Average Total Oxygen: .000 Average Total Weight%: 99.375
Average Calculated Oxygen: .000 Average Atomic Number: 10.811
Average Excess Oxygen: .000 Average Atomic Weight: 20.040
Average ZAF Iteration: 7.00 Average Quant Iterate: 2.00
Un 3 SiO2 glass, Results in Elemental Weight Percents
ELEM: Si O Al Cl
BGDS: EXP EXP EXP LIN
TIME: 60.00 60.00 60.00 60.00
BEAM: 49.82 49.82 49.82 49.82
ELEM: Si O Al Cl SUM
122 46.514 52.881 .004 .004 99.403
123 46.538 52.747 .004 -.003 99.285
124 46.572 52.861 .006 -.003 99.436
125 46.540 52.787 .005 -.003 99.329
126 46.586 52.829 .006 .002 99.423
AVER: 46.550 52.821 .005 .000 99.375
SDEV: .029 .055 .001 .003 .065
SERR: .013 .024 .000 .001
%RSD: .06 .10 23.08 -815.86
STDS: 914 914 336 285
STKF: .4101 .2664 .1331 .0601
STCT: 687.97 250.02 725.07 78.20
UNKF: .4086 .2637 .0000 .0000
UNCT: 685.39 247.54 .21 .00
UNBG: .97 1.28 3.17 .32
ZCOR: 1.1394 2.0028 1.2278 1.2803
KRAW: .9962 .9901 .0003 -.0001
PKBG: 705.66 194.79 1.07 1.00
The SiO2 crystal looks fine because it was run at the exact same conditions as the SiO2 (crystal) standard, but the SiO2 glass is a little low in oxygen due to the different TDI effects for glass.
The quant results running both materials as unknowns (using SiO2 crystal as the primary standard) is here with the TDI correction:
Un 2 SiO2 xtal
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 50.0 Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 12/03/2013 02:48:14 PM to 12/03/2013 02:57:40 PM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for o ka
WARNING- Using Exponential Off-Peak correction for al ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
Average Total Oxygen: .000 Average Total Weight%: 100.335
Average Calculated Oxygen: .000 Average Atomic Number: 10.802
Average Excess Oxygen: .000 Average Atomic Weight: 20.024
Oxygen Equiv. from Halogen: .000 Halogen Corrected Oxygen: .000
Average ZAF Iteration: 7.00 Average Quant Iterate: 2.00
Un 2 SiO2 xtal, Results in Elemental Weight Percents
ELEM: Si O Al Cl
BGDS: EXP EXP EXP LIN
TIME: 60.00 60.00 60.00 60.00
BEAM: 49.82 49.82 49.82 49.82
ELEM: Si O Al Cl SUM
117 46.871 53.523 .005 .001 100.400
118 46.788 53.315 .000 .000 100.102
119 46.907 53.558 .001 .000 100.466
120 46.786 53.323 .000 .003 100.113
121 46.931 53.658 .005 .001 100.595
AVER: 46.857 53.475 .002 .001 100.335
SDEV: .067 .151 .003 .001 .219
SERR: .030 .068 .001 .001
%RSD: .14 .28 121.49 112.65
STDS: 914 914 336 285
STKF: .4101 .2664 .1331 .0601
STCT: 689.39 243.24 724.48 83.43
UNKF: .4111 .2675 .0000 .0000
UNCT: 691.10 244.22 .10 .01
UNBG: .98 1.38 3.19 .32
ZCOR: 1.1397 1.9994 1.2286 1.2799
KRAW: 1.0025 1.0040 .0001 .0001
PKBG: 707.67 178.58 1.03 1.04
TDI%: .396 -2.869 -.408 -.238
DEV%: .3 .4 2.5 9.2
TDIF: LINEAR QUADRA LINEAR LINEAR
TDIT: 84.20 84.60 83.60 84.20
TDII: 692. 244. 3.27 .331
Un 3 SiO2 glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 50.0 Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 12/03/2013 03:00:25 PM to 12/03/2013 03:09:47 PM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for o ka
WARNING- Using Exponential Off-Peak correction for al ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
Average Total Oxygen: .000 Average Total Weight%: 100.645
Average Calculated Oxygen: .000 Average Atomic Number: 10.773
Average Excess Oxygen: .000 Average Atomic Weight: 19.971
Average ZAF Iteration: 7.00 Average Quant Iterate: 2.00
Un 3 SiO2 glass, Results in Elemental Weight Percents
ELEM: Si O Al Cl
BGDS: EXP EXP EXP LIN
TIME: 60.00 60.00 60.00 60.00
BEAM: 49.82 49.82 49.82 49.82
ELEM: Si O Al Cl SUM
122 46.507 54.165 .004 .004 100.681
123 46.353 54.176 .004 -.003 100.530
124 46.612 54.116 .006 -.002 100.731
125 46.438 54.070 .005 -.002 100.510
126 46.611 54.154 .006 .002 100.773
AVER: 46.504 54.136 .005 .000 100.645
SDEV: .112 .043 .001 .003 .119
SERR: .050 .019 .001 .001
%RSD: .24 .08 22.98 -944.62
STDS: 914 914 336 285
STKF: .4101 .2664 .1331 .0601
STCT: 689.83 243.44 724.69 83.31
UNKF: .4075 .2724 .0000 .0000
UNCT: 685.50 248.91 .22 .00
UNBG: .97 1.28 3.17 .32
ZCOR: 1.1411 1.9876 1.2313 1.2786
KRAW: .9937 1.0225 .0003 .0000
PKBG: 705.77 195.85 1.07 1.00
TDI%: .016 .554 .656 2.221
DEV%: .3 .4 2.9 3.8
TDIF: LINEAR LINEAR LINEAR LINEAR
TDIT: 83.20 84.00 83.20 83.40
TDII: 686. 250. 3.41 .323
One thing here is that it would be nice to have the button (in std assignments) that now says "remove TDI correction" to default to "add TDI correction", so that it would be done for all TDI-specified elements, sor even better, to invoke the TDI correction by default if it has been checked to use it in Special Options (then you can default the button in std assignments to "remove TDI", but if you do click it, then the button should change to "use TDI".
Right now we still have to click on each element and specify the use of TDI even though we have said to acquire using TDI in Special Options in Acquire. Every time we run an analysis, we have to do this, even though the stored setup had TDI invoked. If we do point by point acquisition and do the TDI specification on the first point of the file, it will turn it off again on the next point, so if we want to look at the numbers as we go, we have to redo the TDI on this file (in std. assignments) after each point.
Quote from: Mike Jercinovic on February 18, 2014, 06:57:30 AM
One thing here is that it would be nice to have the button (in std assignments) that now says "remove TDI correction" to default to "add TDI correction", so that it would be done for all TDI-specified elements, sor even better, to invoke the TDI correction by default if it has been checked to use it in Special Options (then you can default the button in std assignments to "remove TDI", but if you do click it, then the button should change to "use TDI".
Hi Mike,
Let me make sure I understand what you are asking here...
Are you merely saying you want to be able to "toggle" the TDI correction on and off so one can see the analysis with and without TDI correction? If so, you can do that from the Analytical | Analysis Options menu dialog as seen here:
(https://smf.probesoftware.com/oldpics/i57.tinypic.com/xnd7hx.jpg)
In fact, every correction Probe for EPMA performs on your data can be "toggled" on and off globally for the entire run from this dialog above.
The Remove TDI Correction button in the Standard Assignments dialog actually removes the TDI assignments from the specified samples, so reversing that is problematic (maybe not so much for the *self* TDI correction, but for the *assigned* TDI correction certainly).
Quote from: Mike Jercinovic
Right now we still have to click on each element and specify the use of TDI even though we have said to acquire using TDI in Special Options in Acquire. Every time we run an analysis, we have to do this, even though the stored setup had TDI invoked. If we do point by point acquisition and do the TDI specification on the first point of the file, it will turn it off again on the next point, so if we want to look at the numbers as we go, we have to redo the TDI on this file (in std. assignments) after each point.
If you want to have the TDI assignments used throughout the run simply turn them on in the first sample (even if there's no data) and all subsequent samples should automatically utilize those assignments.
On the other hand, if you're using sample setups to create new samples, make sure the specified sample setup has the TDI assignments are turned on and they should be brought forward.
The program is designed to automatically turn on the TDI assignments automatically when the sample is acquired as seen here:
(https://smf.probesoftware.com/oldpics/i60.tinypic.com/rumwqs.jpg)
Of course one can also select all samples and turn on the TDI assignments that way also. I'm probably missing something, so please let me know if I have...
Well, we are not so much interested in toggling TDI off and on...we just would like TDI to be defaulted to actively being used once we have specified for it to do so. Maybe it's just our system, but once we have a unknown sample setup, and have specified to use TDI in special options, and specified to use TDI in analysis options (quantitative analysis options), then go and click on the standard assignments (in analyze), click on each element we want to use TDI (U, Th, and Pb) and click the button to "use TDI self calibration correction", click OK, then store this unknown sample as a setup (add to setup), then digitize something and specify to use that setup, TDI is NOT used. It acquires as a TDI acquisition, but does not calculate the result using TDI until I go back into standard assignments and tell it to use TDI for those elements again. I just did this with a monazite setup, activating TDI for these elements, then storing that as a setup, then digitizing an analysis using that setup. When I look at the newly acquired data in analyze, going into standard assignments and clicking on U, then Th, then Pb, all of them now have the buttons selected to NOT use TDI. So, we dutifully click each one and re-calculate. There is nothing we seem to be able to do to get it to do this properly, so every time we acquire a new unknown sample, we have to activate TDI use for each of these elements.
Hi Mike,
OK, this is interesting. When I tried it from the Acquire! window this morning with a new run and a new sample it acquired the TDI data and when I went in to look at the intensities, the TDI assignment was already specified as I showed above. Maybe you're not "holding your tongue just right"? ;)
Seriously, let's get to the bottom of this. Try a new test run and new sample from scratch and see if you can reproduce the problem there.
Note: There is a "feature" that uses the existing TDI assignments for new samples (e.g., some turned off/some turned on), so maybe what you're seeing is based on that feature's behavior?
By the way if you select multiple samples, the default assignments that you see in the dialog are based on the *last* sample selected in the Analyze! sample list.
Edit: are the TDI assignments already made to the sample setup used for the acquisition?
It's probably just us. Here is the first example...
1) start new database
2) new unknown sample (in Acquire), call it monazite setup
3) select new sample from file, navigate to the last database where monazite was run, and pick up an unknown that used, and specified TDI
4) in Acquire, go to special options and make sure that the use TDI button is activated
5) go to analysis options and make sure the use TDI option is checked
6) go to Analyze and then into standard assignments, check whether TDI is activated for U, Th, Pb...it is not, so we activate TDI for each of these elements, click OK with each, then click OK for the main standard assignments window.
7) with this new unknown still highlighted, click to store it as a setup (in Analyze)
8) go to the Automate window and digitize a new unknown
9) digitize a 6-pt grid
10) specify for this unknown to use the just-stored setup (monazite setup)
11) run the newly digitized sample, making sure that the use specified setups button is active
12) the analysis completes, click OK
13) now go to standard assignments for the newly acquired unknown,
14) for U, Th, and Pb, it shows now that DO NOT USE TDI is active, so we have to then activate TDI (self cal) for each of these elements.
Just to be sure it did not actually do the calculated intensities with TDI even though the TDI buttons are not apparently active, you can run analyze before going back to check the standard assignments to see the results, then go into standard assignments and check the use TDI (self) buttons and re-run analyze. Sure enough, the results change as they should (in this case to very slightly lower the intensities, as counts for these three elements are all slightly increasing with time).
I we now store this new unknown as a setup and use it for digitized samples, the manifestation is the same, TDI will not be active for U, Th, and Pb until we go back into standard assignments and re-specify TDI again.
Example 2...
1) in Acquire, start a new unknown sample
2) select to specify that you are choosing to base this sample on an existing setup, this setup is an unknown we have just run, and specified for U, Th and Pb to use TDI, then stored that as a setup.
3) make sure in special options that use TDI is selected, it is, and that use TDI in analysis options is also still checked (it is)
4) run one point with start acquisition in the Acquire window
5) once this point has completed (motion ready), go to the Analyze window and to standard assignments, Look at U, Th and Pb, now they have "use TDI (self cal)" selected automatically and we don't have to change anything - it's working great, but...
6) now run a second point from start acquisition in the Acquire window
7) once this point is finished, go to standard assignments in Analyze
8) look at the TDI assignments for U, Th, Pb...now they are all shut OFF (that is, DO NOT USE TDI is now selected), so now for this point, and all subsequent points for this file, we have to always go back into Analyze-standard assignments, and specify for each element (U, Th, Pb) to use TDI.
That's just the way it works for us.
Hi Mike,
Hmmm.... well I tried using a sample setup from the Automate! window and it seems to work just fine. I did find a small display issue which is now fixed in v. 10.2.7 so go ahead and update and try tis new version.
It might be necessary for your to create a small test run with just a couple of elements that shows the behavior you are seeing for me to see it also. If you send that to me I will take a closer look...
By the way, you can easily see what the TDI flags are for each sample simply by double-clicking the sample in the Analyze! window (or use the Data button) and in the log window, you will note the line highlighted in red here:
Last (Current) On and Off Peak Count Times:
ELEM: na ka si ka ti ka
BGD: OFF OFF OFF
BGDS: LIN LIN LIN
SPEC: 1 2 3
CRYST: TAP LPET LLIF
ORDER: 1 1 1
ONTIM: 20.00 20.00 20.00
HITIM: 5.00 5.00 5.00
LOTIM: 5.00 5.00 5.00
Miscellaneous Sample Acquisition/Calculation Parameters:
KILO: 15.00 15.00 15.00
ENERGY 1.041 1.740 4.509
EDGE: 1.073 1.839 4.967
Eo/Ec: 13.98 8.16 3.02
STDS: 301 301 22
TDI#: -1 -1 0
Just FYI: the TDI assignments shown above do not actually occur until the first data point has been acquired (in case the user changes their mind at the last minute!).
We are running automated TDI acquisitions right now (just using the last unknown sample as the setup basis) and each new sample (combined conditions using both 10 and 50 nA elements) has the TDI assignments properly specified as I watch it running.
So, have you tried acquiring TDI without sample setups, just to see if the TDI assignments are carried forward?
The TDI assignments should also be carried forward with sample setups but we're not using them at the moment so I can't confirm, though it did work in demo mode over the weekend.
I have implemented a new TDI model for ultra beam sensitive samples. It is based on the Log(intensities) as before, but now also includes a log function of time (X axis) in order to perform a full double exponential fit. For certain very beam sensitive samples, this may be a useful addition to our tool kit.
Let's start with a very beam sensitive material, K-375 NIST glass. This material has 10.42 wt% Na, 31.8 wt% Si and some Zn, U and the balance oxygen...
Here is an "analysis" of this quite nasty material *without* any TDI correction:
St 173 Set 24 K-0375 NBS glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 100. Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
from John Rutledge
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 05/10/2012 02:30:56 AM to 05/10/2012 02:38:17 AM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for p ka
Average Total Oxygen: .000 Average Total Weight%: 92.534
Average Calculated Oxygen: .000 Average Atomic Number: 16.903
Average Excess Oxygen: .000 Average Atomic Weight: 22.922
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
SPEC: Zn Ba U O
TYPE: SPEC SPEC SPEC SPEC
AVER: 4.940 10.370 .110 42.320
SDEV: .000 .000 .000 .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P SUM
371 .207 34.826 .002 .007 .004 92.786
372 .192 34.695 .005 -.008 .012 92.635
373 .235 34.488 .008 -.014 .014 92.471
374 .175 34.505 .001 -.029 .008 92.400
375 .146 34.501 .001 .013 -.021 92.379
AVER: .191 34.603 .003 -.006 .003 92.534
SDEV: .034 .151 .003 .017 .014 .173
SERR: .015 .068 .001 .008 .006
%RSD: 17.56 .44 86.81 -273.01 412.85
PUBL: 10.420 31.830 n.a. n.a. n.a. 99.990
%VAR: -98.17 8.71 --- --- ---
DIFF: -10.229 2.773 --- --- ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 76.73 79.39 602.77 66.49 40.15
UNKF: .0009 .2806 .0000 -.0001 .0000
UNCT: .92 54.33 .05 -.04 .01
UNBG: 3.34 .16 1.23 .99 .05
ZCOR: 2.1585 1.2330 1.0674 1.1528 1.4789
KRAW: .0120 .6843 .0001 -.0006 .0001
You will note that the concentration error for Na is around 98 % relative accuracy, when this material treated as a "normal sample"... Si isn't too great either, but is off 9% relative accuracy or so. So clearly we need some kind of a Time Dependent Intensity (TDI) correction method.
So, next we will turn on the "traditional" Lin-Log TDI extrapolation which fits a straight line to a plot of the Log(Na) intensities and applies the slope to obtain these results: for Na and Si:
St 173 Set 24 K-0375 NBS glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 100. Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
from John Rutledge
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 05/10/2012 02:30:56 AM to 05/10/2012 02:38:17 AM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for p ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
Average Total Oxygen: .000 Average Total Weight%: 92.158
Average Calculated Oxygen: .000 Average Atomic Number: 16.907
Average Excess Oxygen: .000 Average Atomic Weight: 22.894
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
SPEC: Zn Ba U O
TYPE: SPEC SPEC SPEC SPEC
AVER: 4.940 10.370 .110 42.320
SDEV: .000 .000 .000 .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P SUM
371 .467 34.359 .001 .007 .004 92.577
372 .427 33.997 .005 -.008 .012 92.173
373 .522 33.827 .008 -.014 .014 92.097
374 .375 34.025 .001 -.029 .008 92.121
375 .314 33.775 .001 .013 -.021 91.822
AVER: .421 33.997 .003 -.006 .003 92.158
SDEV: .081 .229 .003 .017 .014 .271
SERR: .036 .102 .001 .008 .006
%RSD: 19.19 .67 87.96 -273.01 412.65
PUBL: 10.420 31.830 n.a. n.a. n.a. 99.990
%VAR: -95.96 6.81 --- --- ---
DIFF: -9.999 2.167 --- --- ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 77.91 79.30 603.55 66.49 40.15
UNKF: .0019 .2752 .0000 -.0001 .0000
UNCT: 2.06 53.21 .05 -.04 .01
UNBG: 3.34 .16 1.23 .99 .05
ZCOR: 2.1621 1.2355 1.0669 1.1527 1.4764
KRAW: .0265 .6710 .0001 -.0006 .0001
TDI%: 123.003 -2.060 .962 ---- ----
DEV%: 26.0 .5 33.2 ---- ----
TDIF: LOG-LIN LOG-LIN LOG-LIN ---- ----
TDIT: 74.20 74.40 71.80 ---- ----
TDII: 7.71 53.3 1.28 ---- ----
Well, that wasn't too much of a help, was it? The Na average came up considerably from 0.191 to 0.421 (though far short of the expected published value of 10.42 wt%!), but the Si dropped by even more (34.6 to 33.9 wt% absolute), so the total actually decreased slightly! Even though, the TDI% correction was over 100% for Na! Why is this?
Lets start by looking at these "traditional" TDI log intensity plots for Na and Si on this K-375 NIST glass...
(https://smf.probesoftware.com/oldpics/i60.tinypic.com/15cgak5.jpg)
(https://smf.probesoftware.com/oldpics/i59.tinypic.com/295u70y.jpg)
Well clearly the Na extrapolation back to zero time is not a good fit at all, while the Si is not quite as bad, we can still see that we have not properly modeled the initial intensity changes in the first few seconds for either element, but particularly Na. Remember, these are Log(intensity) plots and should therefore plot any exponential process as a straight line, but obviously not with this particular sample under 100 nA conditions!
So now we will try the next tool in our arsenal, the hyper-exponential TDI fit, which assumes that the change in Log(intensity) is modeled by a 2nd order polynomial in lin-log space as seen here in the plots for Na and Si again:
(https://smf.probesoftware.com/oldpics/i60.tinypic.com/ifnz2c.jpg)
(https://smf.probesoftware.com/oldpics/i62.tinypic.com/125mmp1.jpg)
Much improved fits it would appear, though Na is still not modeled well in the first seconds of the TDI acquisition, though Si is less poorly modeled. What about the quant results?
St 173 Set 24 K-0375 NBS glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 100. Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
from John Rutledge
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 05/10/2012 02:30:56 AM to 05/10/2012 02:38:17 AM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for p ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
Average Total Oxygen: .000 Average Total Weight%: 91.991
Average Calculated Oxygen: .000 Average Atomic Number: 16.892
Average Excess Oxygen: .000 Average Atomic Weight: 22.858
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
SPEC: Zn Ba U O
TYPE: SPEC SPEC SPEC SPEC
AVER: 4.940 10.370 .110 42.320
SDEV: .000 .000 .000 .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P SUM
371 1.266 33.478 .001 .007 .004 92.496
372 1.012 33.272 .005 -.008 .012 92.034
373 1.331 33.076 .008 -.014 .014 92.155
374 .902 32.973 .001 -.029 .008 91.596
375 .744 33.197 .001 .013 -.021 91.675
AVER: 1.051 33.199 .003 -.006 .003 91.991
SDEV: .246 .193 .003 .017 .014 .367
SERR: .110 .086 .001 .008 .006
%RSD: 23.41 .58 87.97 -273.02 413.22
PUBL: 10.420 31.830 n.a. n.a. n.a. 99.990
%VAR: -89.91 4.30 --- --- ---
DIFF: -9.369 1.369 --- --- ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 77.91 79.30 603.55 66.49 40.15
UNKF: .0049 .2677 .0000 -.0001 .0000
UNCT: 5.15 51.77 .05 -.04 .01
UNBG: 3.34 .16 1.23 .99 .05
ZCOR: 2.1621 1.2400 1.0660 1.1524 1.4730
KRAW: .0662 .6529 .0001 -.0006 .0001
PKBG: 2.54 320.00 1.04 .97 1.26
TDI%: 454.003 -4.704 .962 ---- ----
DEV%: 15.8 .4 33.2 ---- ----
TDIF: HYP-EXP HYP-EXP LOG-LIN ---- ----
TDIT: 74.20 74.40 71.80 ---- ----
TDII: 14.5 52.3 1.28 ---- ----
Now our Na TDI% correction is over 450%, but we are still off by 90% in relative accuracy as we've only gone from 0.42 wt% Na in the traditional extrapolation to around 1 wt% with this "hyper-exponential" TDI fit, and we are therefore still under correcting this extremely beam sensitive material...
So, here is where I would like to introduce a new TDI extrapolation model, the Logarithmic extrapolation or log-log fit or "double-exponential" model. The previously existing linear and hyper-exponential TDI methods are summarized in the previous post. Let's take a look first at the TDI plots using this new double exponential fit:
(https://smf.probesoftware.com/oldpics/i59.tinypic.com/2v2ve4z.jpg)
(https://smf.probesoftware.com/oldpics/i60.tinypic.com/2q8t742.jpg)
The extrapolations are much improved, at least to the eye, so now let's look at the quant results again:
St 173 Set 24 K-0375 NBS glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 100. Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
from John Rutledge
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 05/10/2012 02:30:56 AM to 05/10/2012 02:38:17 AM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for p ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
Average Total Oxygen: .000 Average Total Weight%: 97.309
Average Calculated Oxygen: .000 Average Atomic Number: 16.572
Average Excess Oxygen: .000 Average Atomic Weight: 22.868
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
SPEC: Zn Ba U O
TYPE: SPEC SPEC SPEC SPEC
AVER: 4.940 10.370 .110 42.320
SDEV: .000 .000 .000 .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P SUM
371 7.358 33.896 .001 .007 .004 99.006
372 5.900 33.248 .005 -.008 .012 96.897
373 6.969 32.999 .008 -.014 .014 97.717
374 5.572 33.286 .001 -.029 .008 96.579
375 5.781 32.830 .001 .013 -.021 96.344
AVER: 6.316 33.252 .003 -.006 .003 97.309
SDEV: .795 .406 .003 .017 .014 1.082
SERR: .355 .181 .001 .008 .006
%RSD: 12.58 1.22 87.96 -272.99 412.40
PUBL: 10.420 31.830 n.a. n.a. n.a. 99.990
%VAR: -39.39 4.47 --- --- ---
DIFF: -4.104 1.422 --- --- ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 77.91 79.30 603.55 66.49 40.15
UNKF: .0302 .2643 .0000 -.0001 .0000
UNCT: 32.04 51.11 .05 -.04 .01
UNBG: 3.34 .16 1.23 .99 .05
ZCOR: 2.0906 1.2580 1.0656 1.1519 1.4697
KRAW: .4113 .6446 .0001 -.0006 .0001
PKBG: 10.59 315.92 1.04 .97 1.26
TDI%: 3412.187 -5.918 .962 ---- ----
DEV%: 11.8 .4 33.2 ---- ----
TDIF: LOG-LOG LOG-LOG LOG-LIN ---- ----
TDIT: 74.20 74.40 71.80 ---- ----
TDII: 31.8 51.1 1.28 ---- ----
Ok, so that is better and now we are "only" off in accuracy for Na by around 40% relative (6.3 wt% compared to the published value of 10.4 wt%). Interestingly our Si value is very slightly worse than the "hyper-exponential" fit. The total averages 97% which is not good, but much better than before.
Are we done, well maybe... if we look again at the log-log plots it does appear that we are still slightly under estimating the TDI correction in the first few seconds. What can we do?
Well let's try "weighting" the first few data points in the acquisition, since these measurements should obviously be the closer to the zero time intensity, by utilizing this option in the Analytical | Analysis Options dialog as seen here:
(https://smf.probesoftware.com/oldpics/i57.tinypic.com/9ps1af.jpg)
By entering a value to "2", we weight the first point times 2, if we enter say "3" we weight the first point times 3 and the second point times 2, if we enter a "4" we weight the first point 4 times, second point 3 times, third point 2 times, etc., etc. Here is what we obtain quantitatively with just weighting the first point times 2:
St 173 Set 24 K-0375 NBS glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 100. Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
from John Rutledge
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 05/10/2012 02:30:56 AM to 05/10/2012 02:38:17 AM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for p ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
WARNING- Using Time Dependent Intensity (TDI) Weighting Factor of 2
Average Total Oxygen: .000 Average Total Weight%: 98.071
Average Calculated Oxygen: .000 Average Atomic Number: 16.519
Average Excess Oxygen: .000 Average Atomic Weight: 22.855
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
SPEC: Zn Ba U O
TYPE: SPEC SPEC SPEC SPEC
AVER: 4.940 10.370 .110 42.320
SDEV: .000 .000 .000 .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P SUM
371 8.221 33.420 .001 .007 .004 99.394
372 7.202 33.052 .005 -.008 .012 98.003
373 8.104 32.753 .008 -.014 .014 98.605
374 6.835 32.904 .001 -.029 .008 97.459
375 6.694 32.465 .001 .013 -.021 96.893
AVER: 7.411 32.919 .003 -.006 .003 98.071
SDEV: .712 .354 .003 .017 .014 .975
SERR: .318 .159 .001 .008 .006
%RSD: 9.60 1.08 88.39 -272.99 412.33
PUBL: 10.420 31.830 n.a. n.a. n.a. 99.990
%VAR: -28.88 3.42 --- --- ---
DIFF: -3.009 1.089 --- --- ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 77.82 79.39 604.17 66.49 40.15
UNKF: .0356 .2607 .0000 -.0001 .0000
UNCT: 37.74 50.48 .05 -.04 .01
UNBG: 3.34 .16 1.23 .99 .05
ZCOR: 2.0801 1.2625 1.0652 1.1517 1.4679
KRAW: .4849 .6358 .0001 -.0006 .0001
PKBG: 12.30 311.92 1.04 .97 1.26
TDI%: 4041.216 -7.094 1.268 ---- ----
DEV%: 12.1 .4 32.6 ---- ----
TDIF: LOG-LOG LOG-LOG LOG-LIN ---- ----
TDIT: 74.20 74.40 71.80 ---- ----
TDII: 37.6 50.5 1.29 ---- ----
As you can see, there is further improvement. Our total average is now 98%, our Na value is now 7.4 wt% compared to the published value of 10.4 wt%- still a 28% error, but note that the correction is approximately 4000%! Yes, you read that correctly- over 4000% correction. The Si is now within 3.4 % relative accuracy.
Ok, let's try with a weighting of "4" and see what that does:
St 173 Set 24 K-0375 NBS glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 100. Beam Size = 10
(Magnification (analytical) = 40000), Beam Mode = Analog Spot
(Magnification (default) = 400, Magnification (imaging) = 800)
Image Shift (X,Y): .00, .00
from John Rutledge
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 05/10/2012 02:30:56 AM to 05/10/2012 02:38:17 AM
WARNING- Using Exponential Off-Peak correction for si ka
WARNING- Using Exponential Off-Peak correction for p ka
WARNING- Using Time Dependent Intensity (TDI) Element Correction
WARNING- Using Time Dependent Intensity (TDI) Weighting Factor of 4
Average Total Oxygen: .000 Average Total Weight%: 98.809
Average Calculated Oxygen: .000 Average Atomic Number: 16.471
Average Excess Oxygen: .000 Average Atomic Weight: 22.847
Average ZAF Iteration: 4.00 Average Quant Iterate: 2.00
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
SPEC: Zn Ba U O
TYPE: SPEC SPEC SPEC SPEC
AVER: 4.940 10.370 .110 42.320
SDEV: .000 .000 .000 .000
ELEM: Na Si Ca Fe P
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P SUM
371 9.103 33.145 .001 .007 .004 100.000
372 8.228 32.857 .005 -.008 .012 98.834
373 9.077 32.640 .008 -.014 .014 99.465
374 7.914 32.672 .001 -.029 .008 98.307
375 7.449 32.258 .001 .013 -.021 97.441
AVER: 8.354 32.715 .003 -.006 .003 98.809
SDEV: .726 .325 .003 .017 .014 .997
SERR: .325 .145 .001 .008 .006
%RSD: 8.70 .99 88.90 -273.00 412.36
PUBL: 10.420 31.830 n.a. n.a. n.a. 99.990
%VAR: -19.83 2.78 --- --- ---
DIFF: -2.066 .885 --- --- ---
STDS: 336 14 285 162 285
STKF: .0735 .4101 .3596 .0950 .1599
STCT: 77.78 79.47 604.98 66.49 40.15
UNKF: .0404 .2584 .0000 -.0001 .0000
UNCT: 42.72 50.07 .05 -.04 .01
UNBG: 3.34 .16 1.23 .99 .05
ZCOR: 2.0704 1.2661 1.0649 1.1516 1.4666
KRAW: .5492 .6301 .0001 -.0006 .0001
PKBG: 13.79 309.41 1.04 .97 1.26
TDI%: 4588.661 -7.842 1.467 ---- ----
DEV%: 11.2 .4 31.9 ---- ----
TDIF: LOG-LOG LOG-LOG LOG-LIN ---- ----
TDIT: 74.20 74.40 71.80 ---- ----
TDII: 42.6 50.1 1.29 ---- ----
OK, so even more improvement! Our total average is now almost 99% and our relative accuracy error on Na and Si is now 20% and 2.8%. In the case of Na, the TDI% correction is now over 4500%!
We could keep going, but I think we all get the point... which is: we would most likely never want to perform such an acquisition on such a beam sensitive sample at such a high (100 nA) beam current! But... if we absolutely had to, we could give it a go using these new TDI tools!
By the way, here is the Na TDI plot with the 4 times point weighting:
(https://smf.probesoftware.com/oldpics/i58.tinypic.com/e9vjvr.jpg)
And here are the quantitative results with 10x weighting log-log fit to the first TDI intervals:
St 173 Set 24 K-0375 NBS glass, Results in Elemental Weight Percents
ELEM: Na Si Ca Fe P Zn Ba U O
TYPE: ANAL ANAL ANAL ANAL ANAL SPEC SPEC SPEC SPEC
BGDS: LIN EXP LIN LIN EXP
TIME: 20.00 20.00 20.00 20.00 20.00
BEAM: 100.72 100.72 100.72 100.72 100.72
ELEM: Na Si Ca Fe P Zn Ba U O SUM
371 9.642 32.967 .001 .007 .004 4.940 10.370 .110 42.320 100.361
372 8.822 32.773 .005 -.008 .012 4.940 10.370 .110 42.320 99.344
373 9.654 32.545 .008 -.014 .014 4.940 10.370 .110 42.320 99.947
374 8.532 32.488 .001 -.029 .008 4.940 10.370 .110 42.320 98.740
375 7.915 32.109 .001 .013 -.021 4.940 10.370 .110 42.320 97.757
AVER: 8.913 32.576 .003 -.006 .003 4.940 10.370 .110 42.320 99.230
SDEV: .747 .323 .003 .017 .014 .000 .000 .000 .000 1.027
SERR: .334 .145 .001 .008 .006 .000 .000 .000 .000
%RSD: 8.38 .99 89.41 -273.00 412.34 .00 .00 .00 .00
PUBL: 10.420 31.830 n.a. n.a. n.a. 4.940 10.370 .110 42.320 99.990
%VAR: -14.46 2.34 --- --- --- .00 .00 .00 .00
DIFF: -1.507 .746 --- --- --- .000 .000 .000 .000
Maybe not perfect, but certainly better than the alternative!
Edit by John: The observant eye will note that the Na numbers decrease with each point acquisition in the last analysis above. This is due to the beam diameter being 10 um and the points 10 um apart, therefore each acquisition effectively pre-heats the subsequent acquisition volume which reduces the "incubation" time" and therefore decreases the Na intensity more quickly.
Nice! This will be very useful.
Hi Mike,
Thanks, though in some respects I feel this is a "two steps forward/one step back" sort of thing.
As you know, due to "incubation" effects as described here:
http://smf.probesoftware.com/index.php?topic=116.msg454#msg454
This new fit method will now allow the user to not only "under fit" the TDI data, but now, also to "over fit" it! :o
john
I would be very interested in seeing posted user examples of their TDI corrections on beam sensitive samples using this new "double exponential" extrapolation now available in Probe for EPMA 10.3.4...
(https://smf.probesoftware.com/oldpics/i59.tinypic.com/a0fczs.jpg)
With regard to time-dependent-intensity corrections, I gather that one can set the time-weighting option from 1 to 10 in the Analytical options.
Question: If I have only 6 intervals in my TDI curve, what does a time-weighting of 10 actually mean?
Comment: I appear to achieve the best accuracy by adjusting the operating conditions (nA, beam diameter, peak count time) so that the TDI curve stays in the log-linear regime.
It appears that for my hydrous natural dacitic-rhyolitic glasses, that time-weighting of a linear model may provide more accurate results than use of the unweighted log-quadratic (hyperexponential) model.
For anhydrous basaltic glasses at our normal operating conditions, TDI makes very little difference.
Quote from: AndrewLocock on April 18, 2024, 08:55:45 AM
With regard to time-dependent-intensity corrections, I gather that one can set the time-weighting option from 1 to 10 in the Analytical options.
Question: If I have only 6 intervals in my TDI curve, what does a time-weighting of 10 actually mean?
Great question.
For those wondering, Andrew is asking about this feature in the Analytical | Analysis Options dialog:
(https://smf.probesoftware.com/gallery/1_18_04_24_9_47_22.png)
Now this option is briefly explained in the PFE User's Reference:
(https://smf.probesoftware.com/gallery/1_18_04_24_9_47_48.png)
but who reads manuals these days! ;D
So here is the source code that should make it more clear:
pointweight% = 1
If Not UseVolElTimeWeightingFlag Then Exit Sub
If VolElTimeWeightingFactor% < 2 Then Exit Sub
' Calculate point weighting
If ipoint% <= VolElTimeWeightingFactor Then
pointweight% = ipoint% * VolElTimeWeightingFactor% / ipoint% ^ 2
End If
Basically, for each of the measured TDI intensities, a weighting factor is calculated (default = 1), and when the points are added to the regression array, they are weighted according to the code above. If you specify a weighting value larger than the number of points you have, there is basically no effect.
Note that we also fixed a broken Help link in the above dialog and also added better documentation of the TDI parameters in the Report format output as suggested by Andrew (update Probe for EPMA using the Help menu as usual):
QuoteThe intensity data was corrected for Time Dependent Intensity (TDI) loss (or gain) using a self calibrated correction for Na ka, K ka, Ti ka, Si ka, O ka.
The TDI data was fit with a Time Weighting Factor of 2
A complete example of the Report format text is here (I pasted it into a code control because it so long and detailed):
Un 19 NBS K-411 mineral glass
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 10.0 Beam Size = 20
(Magnification (analytical) = 20000), Beam Mode = Analog Spot
(Magnification (default) = 600, Magnification (imaging) = 600)
Image Shift (X,Y): .00, .00
Compositional analyses were acquired on an electron microprobe equipped with 5 tunable wavelength dispersive spectrometers.
Operating conditions were 40 degrees takeoff angle, and a beam energy of 15 keV.
The beam current was 10 nA, and the beam diameter was 20 microns.
Elements were acquired using analyzing crystals LLIF for Ti ka, Fe ka, Mn ka, Ca ka, PET for Cl ka, Ba la, K ka, TAP for Na ka, Mg ka, LTAP for F ka, Si ka, Al ka, TAP for Na ka, Mg ka, and PC1 for O ka.
The standards were MgO synthetic for Mg ka, O ka, TiO2 synthetic for Ti ka, MnO synthetic for Mn ka, NBS K-411 mineral glass for Si ka, Ca10(PO4)6Cl2 (halogen corrected) for Cl ka, Nepheline (partial anal.) for Na ka, Al ka, Diopside (Chesterman) for Ca ka, Orthoclase MAD-10 for K ka, Magnetite U.C. #3380 for Fe ka, and BaF2 (barium fluoride) for Ba la, F ka.
MgO synthetic
1. UCB # M3567, 99.8%, EPMA (UCB): Ca ~ 0.2%
2. C. M. Taylor, 99.98%, EPMA (UCB) Ca ~ 0.02%
SiO2 synthetic
Specimen from ESPI, 99.99%, EPMA (UCB): Al2O3 ~ 0.01%
Catalog #K4699M
Atomic Absorption (Chris Lewis):
Al=15 ppm +/- 5
Fe=6 ppm +/- 3
Mn=1.5 ppm +/- 0.3
Na=5 ppm +/- 3
Li= 2.3 ppm +/- 0.2
TiO2 synthetic
Specimen from Mimports, Lafayette, CA
Assumed stoichiometric
EPMA (UCB): Al2O3=0.02 (interference corrected)
Fluor-phlogopite (halogen corrected)
Grown by S. Wones, Univ of Tenn
(applied F=O equivalence)
Ca10(PO4)6Cl2 (halogen corrected)
Specimen from Alan Baumer, Univ of Nice, France
Hydrothermally grown
See Argiolas and Baumer, Can. Min., v. 16, pp 285-290, 1978
Nepheline (partial anal.)
Analysis by ISE Carmichael (Na, K)
Ca = 750 PPM (EPMA by JJD)
Diopside (Chesterman)
Twin Lakes, Fresno Co., CA
From Charles Chesterman (Ca Div. Mines)
Orthoclase MAD-10
Specimen from Chuck Taylor
Fe2O3=2.01% (EPMA by J. Donovan) (as FeO=1.88% + 0.13% O)
K2O=15.49%, Na2O=1.07% (Flame photometry by J. Hampel)
BaO=0.06%, Rb2O=0.03% (EPMA by J. Donovan)
Sr=12 ppm, Rb=600 ppm (Isotope dilution)
Magnetite U.C. #3380
Port Henry, NY
FeO=30.93% (ISE Carmichael)
Fe2O3=68.85%, FeO=30.92% (as FeO=92.73% + 6.90% O)
(Total FeO=92.73%, by EPMA, JJD)
MnO synthetic
Specimen from Michael Wittenauer (Purdue Univ.)
Starting mat'l 99.999%, SM # 317, 'skull melt' process
Mat. Res. Bull. 15, p 571, 1980
(possible intergrowths of Mn3O4 and small inclusions of Mn metal)
EPMA (UCB): SiO2=0.00, FeO=0.00, CaO=0.00, Al2O3=0
NiO synthetic
1. Specimen from Michael Wittenauer (Purdue Univ.)
Starting mat'l 99.999%, Boule WI, Arc Transfer
2. Specimen from G. Czemanske, USGS (Oct 12, 1984)
EPMA (UCB): FeO=0.05%
-----------------------------
All material assumed stoichiometric
NBS K-412 mineral glass
SRM 470, NIST
C.M. Taylor (Photometry?) FeO 2.77, Fe2O3 8.15
Total as FeO 10.10, Excess O 0.815
Na = 430 PPM (EPMA by JJD)
NBS K-411 mineral glass
SRM 470, NIST
C.M. Taylor (Photometry?) FeO 4.39, Fe2O3 11.23
Total as FeO 14.49, Excess O 1.12
BIR-1G Glass
USGS
see Meeker, et. al. "A Basalt Glass Standard for Multiple Microanalytical Techniques"
BaF2 (barium fluoride)
Single crystal, fluorescent
The counting time was 10 seconds for Cl ka, Ti ka, Mn ka, 20 seconds for K ka, Ba la, Ca ka, Si ka, Al ka, 40 seconds for F ka, Fe ka, 60 seconds for Na ka, Mg ka, and 120 seconds for O ka.
The intensity data was corrected for Time Dependent Intensity (TDI) loss (or gain) using a self calibrated correction for Na ka, K ka, Ti ka, Si ka, O ka.
The TDI data was fit with a Time Weighting Factor of 2
The off peak counting time was 10 seconds for Cl ka, Mn ka, Ti ka, and 20 seconds for Ba la, F ka, K ka, O ka.
Off Peak correction method was Linear for Mn ka, Cl ka, Ba la, F ka, K ka, Low Only for Ti ka, and Exponential for O ka.
The MAN background intensity data was calibrated and continuum absorption corrected for Na ka, Fe ka, Ca ka, Si ka, Al ka, Mg ka.
Donovan, J. J., & Tingle, T. N. (1996). An improved mean atomic number background correction for quantitative microanalysis. Microscopy and Microanalysis, 2(1), 1-7.
Donovan, J. J., Singer, J. W., & Armstrong, J. T. (2016). A new EPMA method for fast trace element analysis in simple matrices. American Mineralogist, 101(8), 1839-1853.
Unknown and standard intensities were corrected for deadtime using the Normal (traditional single term) correction method.
Donovan, J. J., Moy, A., von der Handt, A., Gainsforth, Z., Maner, J. L., Nachlas, W., & Fournelle, J. (2023). A New Method for Dead Time Calibration and a New Expression for Correction of WDS Intensities for Microanalysis. Microscopy and Microanalysis, 29(3), 1096-1110.
Standard intensities were corrected for standard drift over time on an element by element basis.
Interference corrections were applied to Ba for interference by Ti, and to Ti for interference by Ba.
Donovan, J. J., Snyder, D. A., & Rivers, M. L. (1992). An improved interference correction for trace element analysis. In Proceedings of the Annual Meeting-Electron Microscopy Society of America (pp. 1646-1646). San Francisco Press.
Empirical Mass Absorption Coefficients were utilized to correct x-ray intensities for matrix corrections.
Bastin, G. F., & Heijligers, H. J. M. (1991). Quantitative electron probe microanalysis of ultra-light elements (boron-oxygen). In Electron probe quantitation (pp. 145-161). Boston, MA: Springer US.
Bastin, G. F., & Heijligers, H. J. M. (1992). Present and future of light element analysis with electron beam instruments. Microbeam Analysis, 1(2), 61-73.
Current Mass Absorption Coefficients From:
LINEMU Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV
Z-LINE X-RAY Z-ABSOR MAC
Na ka Na 5.6089e+02
Na ka K 3.8110e+03
Na ka Cl 2.5391e+03
Na ka Ba 7.6213e+03
Na ka F 5.1229e+03
Na ka Ti 5.2439e+03
Na ka Fe 8.1986e+03
Na ka Mn 7.2518e+03
Na ka Ca 4.3573e+03
Na ka Si 1.4049e+03
Na ka Al 1.0667e+03
Na ka Mg 8.1441e+02
Na ka O 4.1515e+03
Na ka H 5.9317e+00
K ka Na 3.7714e+02
K ka K 1.7109e+02
K ka Cl 1.1539e+03
K ka Ba 7.2049e+02
K ka F 2.1534e+02
K ka Ti 2.4971e+02
K ka Fe 4.1167e+02
K ka Mn 3.5594e+02
K ka Ca 1.9889e+02
K ka Si 7.4506e+02
K ka Al 5.9083e+02
K ka Mg 5.0887e+02
K ka O 1.6416e+02
K ka H 1.1806e-01
Cl ka Na 7.3634e+02
Cl ka K 3.2806e+02
Cl ka Cl 2.1561e+02
Cl ka Ba 1.2824e+03
Cl ka F 4.2282e+02
Cl ka Ti 4.7326e+02
Cl ka Fe 7.8172e+02
Cl ka Mn 6.7972e+02
Cl ka Ca 3.7594e+02
Cl ka Si 1.4010e+03
Cl ka Al 1.1255e+03
Cl ka Mg 9.8203e+02
Cl ka O 3.2567e+02
Cl ka H 2.6576e-01
Ba la Na 1.6022e+02
Ba la K 7.2502e+02
Ba la Cl 5.2953e+02
Ba la Ba 3.3617e+02
Ba la F 9.0427e+01
Ba la Ti 1.1151e+02
Ba la Fe 1.8314e+02
Ba la Mn 1.5795e+02
Ba la Ca 8.3453e+02
Ba la Si 3.2826e+02
Ba la Al 2.5758e+02
Ba la Mg 2.1898e+02
Ba la O 6.7822e+01
Ba la H 4.2840e-02
F ka Na 1.8327e+03
F ka K 1.0658e+04
F ka Cl 7.5904e+03
F ka Ba 3.1554e+03
F ka F 9.2209e+02
F ka Ti 1.4588e+04
F ka Fe 2.3374e+03
F ka Mn 1.6117e+04
F ka Ca 1.2415e+04
F ka Si 4.2952e+03
F ka Al 3.4208e+03
F ka Mg 2.6263e+03
F ka O 1.2440e+04
F ka H 2.4805e+01
Ti ka Na 1.5590e+02
Ti ka K 7.0770e+02
Ti ka Cl 5.1645e+02
Ti ka Ba 3.2787e+02
Ti ka F 8.7938e+01
Ti ka Ti 1.0869e+02
Ti ka Fe 1.7855e+02
Ti ka Mn 1.5394e+02
Ti ka Ca 8.1470e+02
Ti ka Si 3.1977e+02
Ti ka Al 2.5083e+02
Ti ka Mg 2.1325e+02
Ti ka O 6.5919e+01
Ti ka H 4.1490e-02
Fe ka Na 5.5397e+01
Fe ka K 2.7665e+02
Fe ka Cl 1.9695e+02
Fe ka Ba 6.1414e+02
Fe ka F 3.0620e+01
Fe ka Ti 3.7689e+02
Fe ka Fe 6.8270e+01
Fe ka Mn 5.9704e+01
Fe ka Ca 3.2161e+02
Fe ka Si 1.1782e+02
Fe ka Al 9.1605e+01
Fe ka Mg 7.6877e+01
Fe ka O 2.2548e+01
Fe ka H 1.2590e-02
Mn ka Na 6.8522e+01
Mn ka K 3.3731e+02
Mn ka Cl 2.4097e+02
Mn ka Ba 6.5921e+02
Mn ka F 3.8047e+01
Mn ka Ti 4.5531e+02
Mn ka Fe 8.3286e+01
Mn ka Mn 7.2508e+01
Mn ka Ca 3.9062e+02
Mn ka Si 1.4510e+02
Mn ka Al 1.1272e+02
Mn ka Mg 9.4808e+01
Mn ka O 2.8131e+01
Mn ka H 1.6010e-02
Ca ka Na 2.7733e+02
Ca ka K 1.1737e+03
Ca ka Cl 8.7515e+02
Ca ka Ba 5.5026e+02
Ca ka F 1.5790e+02
Ca ka Ti 1.8677e+02
Ca ka Fe 3.0742e+02
Ca ka Mn 2.6528e+02
Ca ka Ca 1.4983e+02
Ca ka Si 5.5579e+02
Ca ka Al 4.3892e+02
Ca ka Mg 3.7616e+02
Ca ka O 1.1972e+02
Ca ka H 8.1770e-02
Si ka Na 2.2375e+03
Si ka K 9.7768e+02
Si ka Cl 6.5835e+02
Si ka Ba 3.3056e+03
Si ka F 1.3201e+03
Si ka Ti 1.4132e+03
Si ka Fe 2.3053e+03
Si ka Mn 2.0250e+03
Si ka Ca 1.1465e+03
Si ka Si 3.5048e+02
Si ka Al 3.2132e+03
Si ka Mg 2.9015e+03
Si ka O 1.0337e+03
Si ka H 1.0618e+00
Al ka Na 3.3597e+03
Al ka K 1.4794e+03
Al ka Cl 9.9433e+02
Al ka Ba 4.6512e+03
Al ka F 2.0277e+03
Al ka Ti 2.1374e+03
Al ka Fe 3.4392e+03
Al ka Mn 3.0278e+03
Al ka Ca 1.7548e+03
Al ka Si 5.4409e+02
Al ka Al 4.0218e+02
Al ka Mg 4.2884e+03
Al ka O 1.5979e+03
Al ka H 1.8043e+00
Mg ka Na 5.2018e+03
Mg ka K 2.3234e+03
Mg ka Cl 1.5604e+03
Mg ka Ba 6.3391e+03
Mg ka F 3.1803e+03
Mg ka Ti 3.2972e+03
Mg ka Fe 5.2394e+03
Mg ka Mn 4.6163e+03
Mg ka Ca 2.7124e+03
Mg ka Si 8.5871e+02
Mg ka Al 6.3956e+02
Mg ka Mg 4.8748e+02
Mg ka O 2.5312e+03
Mg ka H 3.1956e+00
O ka Na 3.6300e+03 *
O ka K 1.9369e+04
O ka Cl 1.4300e+04 *
O ka Ba 4.5194e+03
O ka F 1.8500e+03 *
O ka Ti 1.9900e+04 *
O ka Fe 4.0000e+03 *
O ka Mn 3.4700e+03 *
O ka Ca 2.4600e+04 *
O ka Si 8.7900e+03 *
O ka Al 6.7200e+03 *
O ka Mg 5.1700e+03 *
O ka O 1.1999e+03
O ka H 5.7430e+01
* indicates empirical MAC
Empirical Mass Absorption Coefficients From:
C:\ProgramData\Probe Software\Probe for EPMA\EMPMAC.DAT
Z-LINE X-RAY Z-ABSOR MAC
O ka Na 3.6300e+03 Love et al. (1974)
O ka Cl 1.4300e+04 Love et al. (1974)
O ka F 1.8500e+03 Love et al. (1974)
O ka Ti 1.9900e+04 Bastin (1992)
O ka Fe 4.0000e+03 Bastin (1992)
O ka Mn 3.4700e+03 Bastin (1992)
O ka Ca 2.4600e+04 Love et al. (1974)
O ka Si 8.7900e+03 Bastin (1992)
O ka Al 6.7200e+03 Bastin (1992)
O ka Mg 5.1700e+03 Bastin (1992)
Area Peak Factors were utilized to correct x-ray intensities for wavelength peak shift and/or shape changes for compound compositions by summing binary APF values.
Bastin, G. F., & Heijligers, H. J. M. (1986). Quantitative electron probe microanalysis of carbon in binary carbides. I—principles and procedures. X-ray Spectrometry, 15(2), 135-141.
Empirical Area Peak Factors (APF) From:
C:\ProgramData\Probe Software\Probe for EPMA\EMPAPF.DAT
Z-LINE X-RAY Z-ABSOR APF RE-NORM
O ka Ti .9796 1.0000 TiO2/Fe2O3/WSi/59.8
O ka Fe .9962 1.0000 Fe3O4/Fe2O3/WSi/59.8
O ka Ca .9700 1.0000 ----/Fe2O3/WSi/59.8
O ka Si 1.0444 1.0000 SiO2/Fe2O3/WSi/59.8, Bastin
O ka Al 1.0213 1.0000 Al2O3/Fe2O3/WSi/59.8, Bastin
Results are the average of 12 points and detection limits ranged from .006 weight percent for Mg ka to .007 weight percent for Si ka to .016 weight percent for Fe ka to .064 weight percent for Ti ka to .080 weight percent for Ba la.
Analytical sensitivity (at the 99% confidence level) ranged from .212 percent relative for O ka to .421 percent relative for Mg ka to 26.044 percent relative for Al ka to 256.124 percent relative for F ka to 2281103.000 percent relative for Ba la.
Goldstein, J. I. (1992). Scanning electron and x-ray microanalysis. A text for biologists, materials scientists, and geologists, 395-416.
Oxygen equivalent from halogens (F/Cl/Br/I), was not subtracted in the matrix correction.
Moy, A., Fournelle, J., Nachlas, W., Dungan, M., Locock, A., Bullock, E., ... & Handt, A. V. D. (2023). On the Importance of Including All Elements in the EPMA Matrix Correction.
The exponential or polynomial background fit was utilized.
Donovan, J. J., Lowers, H. A., & Rusk, B. G. (2011). Improved electron probe microanalysis of trace elements in quartz. American Mineralogist, 96(2-3), 274-282.
The matrix correction method was ZAF or Phi-Rho-Z Calculations and the mass absorption coefficients dataset was LINEMU Henke (LBL, 1985) < 10KeV / CITZMU > 10KeV.
The ZAF or Phi-Rho-Z algorithm utilized was Armstrong/Love Scott prZ (default).
Armstrong, J. T. (1988). Quantitative analysis of silicate and oxide minerals: comparison of Monte Carlo, ZAF and phi-rho-z procedures. Analysis microbeam.
By the way, this topic is a little out of date, so please also check out this topic on TDI methods also:
https://smf.probesoftware.com/index.php?topic=11.0
Quote from: John Donovan on April 18, 2024, 10:02:46 AM]Basically, for each of the measured TDI intensities, a weighting factor is calculated (default = 1), and when the points are added to the regression array, they are weighted according to the code above.
If you specify a weighting value larger than the number of points you have, there is basically no effect.
This is not quite what I see in my data.
For the average of 6 analyses measured at 15 kV, 30 nA, 5 micron beam-diameter in Lipari obsidian (Kuehn et al. 2011),
a linear model for time-dependent-intensity corrections (40 s on peak, divided into
8 interval points)
yielded the following mean values for Na2O (wt%), with standard deviations of the last decimal points given in parentheses:
Time-weighting factor Na2O (wt%)
none 3.54(9)
1 3.54(9)
2 3.66(10)
3 3.72(9)
4 3.76(10)
5 3.79(11)
6 3.82(11)
7 3.84(11)
8 3.89(11)
9 3.90(11)
10 3.91(11)
It appears to me that if I specify a weighting value larger than the number of interval points, there is still a perceptible effect.
In this case, the resultant concentration of Na2O in wt% follows a power-law curve of the form:
f(x) = 3.5442 x0.0429 with R2 = 0.995.
Thanks,
Andrew |
Quote from: AndrewLocock on April 18, 2024, 10:43:05 AM
quote author=John Donovan link=topic=116.msg12569#msg12569 date=1713459766]
QuoteBasically, for each of the measured TDI intensities, a weighting factor is calculated (default = 1), and when the points are added to the regression array, they are weighted according to the code above.
If you specify a weighting value larger than the number of points you have, there is basically no effect.
This is not quite what I see in my data.
For the average of 6 analyses measured at 15 kV, 30 nA, 5 micron beam-diameter in Lipari obsidian (Kuehn et al. 2011),
a linear model for time-dependent-intensity corrections (40 s on peak, divided into 8 interval points)
yielded the following mean values for Na2O (wt%), with standard deviations of the last decimal points given in parentheses:
Time-weighting factor Na2O (wt%)
none 3.54(9)
1 3.54(9)
2 3.66(10)
3 3.72(9)
4 3.76(10)
5 3.79(11)
6 3.82(11)
7 3.84(11)
8 3.89(11)
9 3.90(11)
10 3.91(11)
It appears to me that if I specify a weighting value larger than the number of interval points, there is still a perceptible effect.
In this case, the resultant concentration of Na2O in wt% follows a power-law curve of the form:
f(x) = 3.5442 x0.0429 with R2 = 0.995.
Thanks,
Andrew |
Yeah, you are correct.
It still adds points to the regression even when the value exceeds the number of actual TDI intervals, but it's a small effect, which is why I said *basically* no effect! :D
A user recently asked me how they could export TDI intensities from Probe for EPMA. The issue being that the "User Specified Output Format" described here:
https://smf.probesoftware.com/index.php?topic=11.msg8327#msg8327
requires quantification of the sample, which means that one needs a primary standard for each element (they were applying the TDI correction to "flank" measurements and did not acquire any primary standard intensities). This is because the TDI correction is generally not applied to the net intensities until the sample is quantified. So if a primary standard is not available to obtain the TDI parameters, one must be utilize another output method.
Here are some other alternative output methods for TDI parameters and intensities:
1. One can view the TDI intensity data in Run | Display Time Dependent (TDI) and Alternating Intensities menu dialog. There is an export button that can be utilized for specific data points:
https://smf.probesoftware.com/index.php?topic=40.msg3970#msg3970
2. Another option is the Output | Save Time Dependent Intensities (TDI) menu, which outputs data for all samples and does not require quantification as seen here after exporting to Excel:
(https://smf.probesoftware.com/gallery/1_27_04_24_8_08_10.png)
3. The extrapolated TDI intensities are also available in the output to the log window in the line labeled "TDII:" as seen here:
ELEM: Na Si K Al Mg Ca Ti Mn Fe P Cr O H
TYPE: ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL ANAL CALC SPEC
BGDS: MAN MAN LIN MAN MAN MAN LIN LIN MAN EXP LIN
TIME: 80.00 30.00 40.00 39.89 60.00 80.00 20.00 20.00 60.00 60.00 30.00 --- ---
BEAM: 19.81 19.81 19.81 19.81 19.81 19.81 19.81 19.81 19.81 19.81 19.81 --- ---
ELEM: Na Si K Al Mg Ca Ti Mn Fe P Cr O H SUM
342 1.419 25.341 .286 6.681 4.361 7.556 1.383 .146 7.345 .106 .030 44.476 .000 99.131
343 1.408 25.413 .275 6.684 4.416 7.831 1.391 .163 7.241 .103 .039 44.681 .000 99.645
344 1.434 25.235 .276 6.624 4.404 7.614 1.477 .137 7.321 .113 .032 44.423 .000 99.091
345 1.404 25.362 .271 6.672 4.413 7.456 1.401 .119 7.385 .100 .035 44.489 .000 99.107
346 1.446 25.267 .293 6.637 4.351 7.443 1.419 .141 7.266 .112 .036 44.323 .000 98.734
347 1.428 25.327 .274 6.618 4.384 7.415 1.400 .136 7.226 .115 .030 44.349 .000 98.702
AVER: 1.423 25.324 .280 6.653 4.388 7.552 1.412 .140 7.297 .108 .034 44.457 .000 99.068
SDEV: .016 .064 .008 .030 .028 .156 .034 .014 .063 .006 .004 .128 .000 .342
SERR: .007 .026 .003 .012 .011 .064 .014 .006 .026 .002 .001 .052 .000
%RSD: 1.14 .25 3.02 .45 .63 2.06 2.43 10.28 .86 5.62 10.64 .29 .00
STDS: 336 162 374 336 162 162 22 25 162 285 396 --- ---
STKF: .0735 .2018 .1132 .1333 .0568 .1027 .5547 .7341 .0950 .1601 .3060 --- ---
STCT: 2517.2 9998.0 5418.2 8306.2 2850.6 337.0 6456.1 14052.2 600.2 9597.6 5218.6 --- ---
UNKF: .0071 .1991 .0025 .0483 .0288 .0698 .0120 .0012 .0617 .0008 .0003 --- ---
UNCT: 243.9 9862.2 121.1 3009.2 1445.9 229.1 139.7 22.4 389.6 46.1 5.0 --- ---
UNBG: 11.0 11.1 30.1 28.2 19.0 1.4 7.1 17.9 7.6 36.1 13.2 --- ---
ZCOR: 1.9968 1.2720 1.1050 1.3779 1.5231 1.0817 1.1763 1.2009 1.1830 1.4108 1.1559 --- ---
KRAW: .0969 .9864 .0224 .3623 .5072 .6798 .0216 .0016 .6490 .0048 .0010 --- ---
PKBG: 23.27 889.29 5.05 107.85 77.23 163.72 21.15 2.25 52.52 2.28 1.38 --- ---
INT%: ---- ---- ---- ---- -.15 ---- ---- ---- .00 ---- ---- --- ---
TDI%: 5.145 .038 .000 .222 .000 .434 -.063 .000 .000 .000 .000 --- ---
DEV%: .4 .1 .0 .1 .0 .4 1.0 .0 .0 .0 .0 --- ---
TDIF: LOG-LIN LOG-LIN ---- LOG-LIN ---- LOG-LIN LOG-LIN ---- ---- ---- ---- --- ---
TDIT: 99.17 49.67 .00 58.33 .00 98.50 37.67 .00 .00 .00 .00 --- ---
TDII: 254. 9873. ---- 3037. ---- 230. 146. ---- ---- ---- ---- --- ---
TDIL: 5.54 9.20 ---- 8.02 ---- 5.44 4.99 ---- ---- ---- ---- --- ---
But this requires a primary standard!
4. The intensity intercepts can also be seen from the Standard Assignments window when plotting the TDI intensities as seen here:
(https://smf.probesoftware.com/gallery/1_27_04_24_8_07_53.png)
Note that there is much discussion on these issues also in this topic:
https://smf.probesoftware.com/index.php?topic=11.msg9000#msg9000