Author Topic: Time Dependent Intensity (TDI) Corrections  (Read 12195 times)

Probeman

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #30 on: June 20, 2018, 09:38:17 am »
Since beam sensitive samples are being discussed in the Cs standard topic by Brian Joy and I just had a student run some very beam sensitive rhyolite glasses earlier this week, I thought we might revisit the the Time Dependent Intensity (TDI) correction feature since the student got some excellent results in a very hydrous alkali glass that entailed some very large corrections.

This was apparently a Bishop Tuff rhyolite pumice which they suspected from FTIR analysis would have around 5 wt% H2O. So we tuned up the instrument for 15 keV, 15 nA and used a 5 um beam (for the Mg, Ca, Cl, Ti and F traces we used a 50 nA beam). Normally we would use a more defocussed 10 um beam to keep the TDI correction a little more reasonable, but the glass bubble walls were very thin, and as they say "necessity is a mother".   :)

Here is the last sample she ran, and note the average correction percent and average variation percent (in red):

Un   55 unknown 147_16, Results in Elemental Weight Percents
 
ELEM:       Na      Si       K      Al      Fe      Mg      Ca      Cl      Ti       F       O       H       P      Mn       S
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    ANAL    CALC    DIFF    SPEC    SPEC    SPEC
BGDS:      MAN     MAN     LIN     MAN     MAN     MAN     MAN     LIN     LIN     LIN
TIME:    40.00   40.00   40.00   40.00   40.00  165.00  150.00  120.00  120.00  120.00     ---     ---     ---     ---     ---
BEAM:    14.91   14.91   14.91   14.91   14.91   50.73   50.73   50.73   50.73   50.73     ---     ---     ---     ---     ---

ELEM:       Na      Si       K      Al      Fe      Mg      Ca      Cl      Ti       F       O       H       P      Mn       S   SUM 
   188   3.108  34.107   3.788   6.193    .460    .018    .294    .096    .021    .041  51.273    .601    .000    .000    .000 100.000
   189   3.378  33.632   3.838   6.347    .486    .018    .290    .092    .026    .044  51.218    .631    .000    .000    .000 100.000
   190   3.415  33.822   3.634   6.267    .585    .017    .289    .085    .033    .061  51.185    .608    .000    .000    .000 100.000

AVER:    3.300  33.854   3.753   6.269    .510    .018    .291    .091    .027    .049  51.225    .614    .000    .000    .000 100.000
SDEV:     .168    .239    .106    .077    .066    .000    .003    .005    .006    .010    .045    .015    .000    .000    .000    .000
SERR:     .097    .138    .061    .045    .038    .000    .002    .003    .004    .006    .026    .009    .000    .000    .000
%RSD:     5.08     .71    2.83    1.23   12.94    2.16     .92    6.01   23.15   21.19     .09    2.52     .00     .00     .00
STDS:      336     162     374     336     162     162     162     285      22     835     ---     ---     ---     ---     ---

STKF:    .0735   .2018   .1132   .1332   .0950   .0568   .1027   .0602   .5547   .1715     ---     ---     ---     ---     ---
STCT:    64.51  244.54  138.78  220.67   20.49   70.15  188.59   61.70   42.06   23.55     ---     ---     ---     ---     ---

UNKF:    .0179   .2768   .0324   .0488   .0042   .0001   .0026   .0007   .0002   .0001     ---     ---     ---     ---     ---
UNCT:    15.72  335.41   39.70   80.80     .91     .15    4.75     .74     .02     .02     ---     ---     ---     ---     ---
UNBG:      .33     .31     .94     .85     .20     .48     .93     .33     .05     .05     ---     ---     ---     ---     ---

ZCOR:   1.8421  1.2230  1.1593  1.2854  1.2090  1.4697  1.1257  1.2548  1.2064  4.1458     ---     ---     ---     ---     ---
KRAW:    .2437  1.3716   .2860   .3662   .0444   .0021   .0252   .0120   .0004   .0007     ---     ---     ---     ---     ---
PKBG:    48.89 1068.36   43.46   96.38    5.47    1.31    6.13    3.26    1.38    1.35     ---     ---     ---     ---     ---
INT%:     ----    ----    ----    ----    ----    ----    ----    ----    ----    -.86     ---     ---     ---     ---     ---

TDI%:  282.195  -2.408  35.459  -2.496   5.719    ----    ----    ----    ----    ----     ---     ---     ---     ---     ---
DEV%:      5.4      .2      .9      .4  1895.2    ----    ----    ----    ----    ----     ---     ---     ---     ---     ---
TDIF:  HYP-EXP LOG-LIN LOG-LIN LOG-LIN LOG-LIN    ----    ----    ----    ----    ----     ---     ---     ---     ---     ---
TDIT:   101.33  102.00  103.67  104.67  104.33    ----    ----    ----    ----    ----     ---     ---     ---     ---     ---
TDII:     12.3    335.    40.5    81.5    1.11    ----    ----    ----    ----    ----     ---     ---     ---     ---     ---
TDIL:     2.51    5.81    3.70    4.40    .106    ----    ----    ----    ----    ----     ---     ---     ---     ---     ---

Un   55 unknown 147_16, Results in Oxide Weight Percents

ELEM:     Na2O    SiO2     K2O   Al2O3     FeO     MgO     CaO      Cl    TiO2       F       O     H2O    P2O5     MnO     SO3   SUM 
   188   4.189  72.966   4.563  11.702    .592    .030    .412    .096    .035    .041    .000   5.375    .000    .000    .000 100.000
   189   4.554  71.952   4.623  11.993    .625    .029    .406    .092    .043    .044    .000   5.639    .000    .000    .000 100.000
   190   4.603  72.357   4.377  11.841    .752    .029    .404    .085    .056    .061    .000   5.436    .000    .000    .000 100.000

AVER:    4.449  72.425   4.521  11.845    .656    .029    .407    .091    .044    .049    .000   5.483    .000    .000    .000 100.000
SDEV:     .226    .511    .128    .146    .085    .001    .004    .005    .010    .010    .000    .138    .000    .000    .000    .000
SERR:     .131    .295    .074    .084    .049    .000    .002    .003    .006    .006    .000    .080    .000    .000    .000
%RSD:     5.08     .71    2.83    1.23   12.94    2.16     .92    6.01   23.15   21.19     .00    2.52     .00     .00     .00
STDS:      336     162     374     336     162     162     162     285      22     835     ---     ---     ---     ---     ---

Note that the H2O by difference is close to 5% which was very nice to see. However, that is in spite of the Na TDI correction is almost 300%, which means that we lost 2/3 of our intensity during the count integration!  The TDI plot for Na looks like this:



We could probably get a little better accuracy by using a slightly shorter integration time.  Here also is the plot for K which was a 35% correction:



and this for Si and Al:





and both are statistically significant corrections if you will compare the TDI%: and DEV%: values for Si and Al.  However, for an element such as Fe, there is no TDI effect, as seen in both the TDI%: and DEV%: values and also from the plot here:



So if you are analyzing hydrous alkali glasses (even with a defocused beam) I hope you are turning on the TDI correction feature!
« Last Edit: June 20, 2018, 09:58:02 am by Probeman »
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AndrewLocock

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #31 on: June 26, 2018, 04:05:35 pm »
Hello,
We run a lot of hydrous rhyolitic glass, and this has encouraged me to look at zeolites in more detail.
However, I noticed that the time-scale for the self-TDI is a bit funny.
Our initial setup is 20 s on peak, with 5 TDI intervals, so the spacing should be every 4 seconds (right?).

A JPG of the screen capture of the TDI data is attached.
The text from the associated DAT file follows:

"Elapsed Time (10 keV, 10 nA,5 um, 4 sec)"   "Na ka Intensity (cps/1nA)"
 3.00000    118.593
 10.0000    113.562
 16.0000    114.460
 23.0000    107.661
 30.0000    102.197

It is not clear to me why the intervals are not an even 4 seconds apart....
Thanks,
Andrew

John Donovan

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #32 on: June 26, 2018, 04:30:10 pm »
Hi Andrew,
It's because the program is recording the elapsed *real time*, not the specified/calculated time.

Due to instrument/software latencies and other delays, we have to use the actual elapsed time to get an accurate TDI slope.
john
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AndrewLocock

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #33 on: June 26, 2018, 04:41:15 pm »
Ok, thanks!

John Donovan

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #34 on: July 28, 2018, 03:55:33 pm »
Dave Adams (USGS Denver) recently sent me an MDB file (probe run file) that he was having a problem with and in sorting that out we noticed (because his run had over 500 unknown samples in it!), that loading the Standard Assignments dialog was taking longer than one would like.

The problem turned out to be due to the fact that the app scans all unknown samples in the current run when loading the Standard Assignments dialog, in order to list all unknown samples that could be utilized in the quantitative blank correction for the selected element (matching element, x-ray, spectrometer and Bragg crystal):

http://probesoftware.com/smf/index.php?topic=454.msg6694#msg6694

So we optimized the code and now that dialog loads about 5 to 8 times faster, which is nice when one has a very large run like Dave had.  Update Probe for EPMA from the Help menu and all will be good.
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Ben Buse

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #35 on: November 28, 2018, 05:34:49 am »
Hi,

Is it possible to export the errors for each TDI point - I'm using Output - Save TDI

Thanks

Ben

John Donovan

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #36 on: November 28, 2018, 07:43:24 am »
Hi,

Is it possible to export the errors for each TDI point - I'm using Output - Save TDI

Thanks

Ben

Hi Ben,
When you say "errors for each TDI point", do you mean the % TDI correction and the % TDI variance for each data point in a sample?
john
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Ben Buse

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #37 on: November 29, 2018, 02:23:03 am »
Hi John,

Sorry I should have made myself clear, I mean the error bars as shown on the figure below



Thanks

Ben

John Donovan

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #38 on: November 29, 2018, 07:57:29 am »
Oh right.  Doing that will disturb the format for those already depending on the existing output, so I can do that but I hope no one minds...
john
« Last Edit: November 29, 2018, 08:05:11 am by John Donovan »
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John Donovan

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #39 on: December 01, 2018, 09:04:19 am »
Hi John,

Sorry I should have made myself clear, I mean the error bars as shown on the figure below



Thanks

Ben

Hi Ben,
I was able to add output of the TDI intensity one sigma error values from the Output menu as seen here:



Let me know if this works for you. 
john
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Ben Buse

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #40 on: December 03, 2018, 07:56:04 am »
Thanks John, this works well

Ben

Ben Buse

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #41 on: March 20, 2019, 09:58:32 am »
Hi John,

How do you calculate the error (% rel) for analyses using TDI, do you simply calculate the counting statistics error, or do you calculate the standard error for the intercept for a linear regression

Thanks

Ben

Probeman

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #42 on: March 20, 2019, 11:20:53 am »
Hi John,

How do you calculate the error (% rel) for analyses using TDI, do you simply calculate the counting statistics error, or do you calculate the standard error for the intercept for a linear regression

Thanks

Ben

In the TDI output to file?  It's counting statistics calculated the same way for the error bars in the TDI plots, but always 1 sigma.
« Last Edit: March 20, 2019, 11:23:10 am by Probeman »
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Ben Buse

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #43 on: April 02, 2019, 09:09:45 am »
Sorry for the slow reply. No I meant in the output of results - (Save analysis output, or save user specified format output)

Thanks

Ben

John Donovan

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Re: Time Dependent Intensity (TDI) Corrections
« Reply #44 on: April 02, 2019, 09:50:38 am »
Yes, they are all 1 sigma counting statistic errors.
John J. Donovan, Pres. 
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