Ah, OK. Based on your "measuring carbon coat thickness" topic and the fact that you posted this in the sample prep board you got me off-track.  So when you mentioned the Calculation Options dialog I thought you were going into the Particle and Thin Film calculations dialog from there trying to determine coating thickness!

OK, if you are only trying to correct for different carbon thicknesses between your standards and your unknowns you will need to specify the carbon thickness for the unknowns (from the Calculation Options dialog), and also for the standards in the Standard | Standard Coating menu dialog, and then you will need to turn on the carbon coat correction options in the Analytical |Analysis Option menu dialog.  Both of them!

This coating correction works well, so if you don't know your carbon coat thickness you'll have to adjust it until you get totals you are expecting.  Not an ideal situation as I'm sure you know.

See here for some details:

https://probesoftware.com/smf/index.php?topic=23.0

This summer/fall we fixed a few bugs in this code (thanks to some excellent sleuthing by Rom), so you'll want to be sure you are updated to the latest PFE v. 13.7.x by updating using the Help menu as usual.

Since we had some difficulty attempting to measure our F Ka k-ratios on TAP crystals, I decided to look at all 5 PET crystals on my instrument, using both Si Ka for high sin thetas and Ti ka for lower sin thetas.

As you may remember from previous posts this was a typical trend that we saw for Si Ka on both TAP and PET crystals:



What we saw above was that for Si ka on PET (high sin thetas) we observed k-ratios falling below the expected k-ratio models (and the EDS k-ratios), while for Si Ka on TAP (at low sin thetas) we saw k-ratios that were above the predicted k-ratios (and the EDS k-ratios).  But will these trends hold up for all PET crystals?

So here are results from some Mg Ka on TAP k-ratio measurements I did a week ago. Unlike the measurements on Si Ka quoted above, this time the EDS agreed quite well with the WDS, except for spectometer 4!  And yes, I am being super careful in adjusting the PHA and stage tilt/focus!

Here is Mg2SiO4:



Diopside:



SRM K-411:



and SRM K-412:



So what the heck is going on here?  Yes, some of these k-ratios appear to be a little high compared to the models as we saw before...

I guess next I'm going to try some replicate measurements on Si ka on TAP and also PET and see if I can at least reproduce the earlier measurements.  Right now I don't see any compelling trends...

We’re using the purple/blue transition on brass as a thickness monitor. We did an emission pattern on a white sheet of paper, which shows us clearly that we shouldn’t coat more than one thin section at a time (although the sample table will take four). On my graphs it would appear that the thinnest coat is a little less than 20nm. The 40 and 60 nm were done by two and three repeat coatings. Regrettably we don’t have any more precise methods of measurement.

Dear Colleagues. We had to purchase a new carbon coater around a year ago, as our trusty old Emitech K950x gave up. The new coater is from Agar (Agar Auto Carbon Coater), and we’re really struggling to control the thickness of the carbon coating and get substantial variations between runs. We thought it might be a clever idea to use the C-Ka signal measured on our LDE2H crystal to create a general calibration curve for individual sections, but what appeared to be a simple idea, doesn’t seem to quite work. There are obviously some matrix effects, and after testing the method on glass, I resorted to making calibration curves on plagioclase, augite and ilmenite (fig. 1). The curves look okay, but when I read off the signals and add a manual thickness estimate in the ‘Analyze’ ‘calculation options’, then the software seems to vastly over-correct. Has anybody had success with a similar idea, or might in any other way share insight into what I may be doing wrong?

That way one can utilize TDI corrections on more than 5 elements in a sample.

But should you do that?

TDI is correcting for the change in intensity over time.
For the first set of elements, measured over time period 1, TDI is correcting for changes in the X-ray emission of the sample and ideally the regression provides data that correspond to "time zero" - the fresh, unirradiated original composition.

If TDI is applied to a second set of elements measured at the same spot, starting at time period 2, it will only be able to correct back to the composition of the sample as it was at the end of time period 1 = the start of time period 2.
The second application of TDI on the same analytical point is correcting back to an already-damaged/changed/altered material, not to the original composition.

It may be argued that some further correction is better than none at all, but it must be realized that a second set of TDI corrections during an analytical routine is not a panacea to obtain the actual original composition.

If the sample is sufficiently beam-sensitive that it continues to change during the measurement of a second set of elements,
perhaps a better analytical scheme should be used.

In the case of most zeolite minerals, for which the Fe content is effectively negligible, I find that simultaneous measurement of the 5 main measurable components: Na, Al, Si (all on TAP), K and Ca (both on PET) with a single application of TDI is sufficient.

Cheers, Andrew