Author Topic: PHA anomalies  (Read 5553 times)

sem-geologist

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Re: PHA anomalies
« Reply #15 on: September 29, 2022, 06:33:26 AM »
First of all, congrats on developing your own spectral interference correction software!  I only know of one other analyst who has done this and he uses the JEOL software, so without Probe for EPMA, as they say, "necessity is a mother!". Two other things come to mind when I read this. 

First, one of the things I do not like about PeakSight is that the standard (and interference) intensities are all stored in a shared database, so they need to be maintained/updated and even worse, they can be overwritten.  Probe for EPMA on the other hand, holds the standards (and interference and MAN) intensities in each user's probe run database so they can never be overwritten.  In fact, although one can easily import the standard intensities from a previous run, one can also easily and automatically re-acquire the standard intensities to obtain the most up to date intensities. I almost always re-run standards for every run every time. And there's also a public "shared" database for saving element setups in PFE, but loading the standard intensities is optional, since as you mentioned, they do get out of date.

Second, it's not discussed very much, but because most labs have difficulty controlling their laboratory temperature, one of the most under rated features in Probe for EPMA is the standard intensity drift correction, which automatically applies a drift correction to all standard intensities for any unknowns when bracketed between standard acquisitions, based on the actual time of acquisition.  This is discussed here:

https://probesoftware.com/smf/index.php?topic=168.msg725#msg725

Thanks, It is not much of tremendous software, just a small tool to scan all binary overlap files and all setup files, and present overlaps as a list of database with some filtering with chemical table, date and tracking live if setup file got updated - absolutely nothing fancy to be honest. It does not correct anything - it is only for construction or modification of set of corrections for selected setup (the .ovl files - the corrections needs to be created at first in PeakSight). All corrections still are done by Peaksight during its matrix correction step - it is only the setup part simplified and validation implemented (checking out for circular corrections - as those are not working on peaksight, and checking for corrections which are not covered by selected element lines and spectrometers in the setup (i.e. removing some lines in setup can leave overlap list in "orphaned" state).

Now the Peaksight got quite far from what it was times ago. Probably it was so terrible in 4.x. In 5.x it was already possible to do calibrations after the analysis and update the already collected analyses by new calibration. From 6.x it addressed annoyance of overwriting of calibrations and automatically adds one digit to the file name. Still it is possible to overwrite, but it needs to be asked for that. To cope with that further from 6.4 Quanti files contain concentrations of standards and raw intensities of standards inside the quantification file, so re-quantification is still possible even if file of standard is overwritten in the future.

As for temperature influence on the diff crystals - I am not sure how this goes like this. Those spectrometers (low pressure) where I observed tremendous 2nd order intensity changes are in opposite side from window. This Year the dehumidifier was stabilizing temperature of room and even during summer our temperatures was not swinging more than 0.8 C. Sincerely, I can't find sense for this small temperature difference to influence the intensities of 2nd order this much.
« Last Edit: September 29, 2022, 06:36:36 AM by sem-geologist »

Probeman

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Re: PHA anomalies
« Reply #16 on: September 29, 2022, 08:54:37 AM »
Now the Peaksight got quite far from what it was times ago. Probably it was so terrible in 4.x. In 5.x it was already possible to do calibrations after the analysis and update the already collected analyses by new calibration. From 6.x it addressed annoyance of overwriting of calibrations and automatically adds one digit to the file name. Still it is possible to overwrite, but it needs to be asked for that. To cope with that further from 6.4 Quanti files contain concentrations of standards and raw intensities of standards inside the quantification file, so re-quantification is still possible even if file of standard is overwritten in the future.

Can you remind me where I can find the version number of the PeakSight software.  I was looking for it yesterday and could not find where it is displayed.

As for temperature influence on the diff crystals - I am not sure how this goes like this. Those spectrometers (low pressure) where I observed tremendous 2nd order intensity changes are in opposite side from window. This Year the dehumidifier was stabilizing temperature of room and even during summer our temperatures was not swinging more than 0.8 C. Sincerely, I can't find sense for this small temperature difference to influence the intensities of 2nd order this much.

It might be worth getting a temperature and humidity logger in the lab and run an set of repeated acquisitions over the weekend and see if anything correlates with the intensity changes.
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Probeman

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Re: PHA anomalies
« Reply #17 on: September 29, 2022, 09:26:43 AM »
Here's a temperature log from 2009 in my lab:


 
That fact that you see this temp/humidity effect more for higher order reflections, than first order reflections, is a really fascinating observation.   I'm trying to think of what that means...

It is true that higher order reflections have higher spectral resolution (smaller FWHM dimensions), so I guess that could be part of the explanation for seeing larger temperature effects on higher order reflections.
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