Virtual Standards

[wrigke]

Hello,

I need to analyze for Xe.  To that end I have gone through the process of setting up a virtual standard.  Everything is OK so far.  Now I need to indicate that some elements interfere with Xe but don't see a straight-forward way of doing so since Xe doesn't populate under "standard assignments".  I tried to add these interferences by going to another standard (e.g. U), going down the list of elements until I find Xe, and then adding in U as an interference.  Then when I press "analyze", I get the following messege:  "No interference counts on interference standard 832 for Xe for sample 832 Uranium".  How do add in elements that interfere with a virtual standard?
Karen

[Probeman]

Hi Karen,
Yes, Philipp Poeml has made the same point.  PFE doesn't yet support interference standards for virtual standards yet.  It's on the "to do" list however... 

[John Donovan]

Karen,
I just thought of something... please send me a small test file with the standards acquired (normal and virtual), just without the interference assignments.

[Philipp Poeml]

Hi, I had some kind of workaround for that, but can't remember now. If interested, I will look it up.

Yes, I was correcting for some La overlap on Xe. I built myself a new software Xe standard that was not virtual and had the PfE correction thing do the rest.

What is your solution, John?

[wrigke]

I would be interested in know what your work around is.  I have been given 120 hours to figure out everything one needs to know about analyzing irradiated fuel and don't have a lot of time to consider work arounds.  I can envision how one would handle one element that overlaps, but when there is more than one, it gets complicated.

Karen

[Philipp Poeml]

For my workaround: It is not easy to explain. It involves in messing with the access database file (mdb) and so on. To put it simple: You make a Xe standard. Then you measure it. Then you open the raw data file and you change the intensity of the fake Xe standard to whatever your virtual intensity is. Then you can use it as a "normal" standard and the interference correction works.

[John Donovan]

I think I might be able to implement interference standards for a virtual standard in Probe for EPMA. I'm working at Probe Software today, so if one of you can send me a small test file with a normal La std and a Xe virtual standard, I would like to test that implementation today if that works for you two...

[Philipp Poeml]

Hi John, My lab is already closed for today. I might try and prepare something for you tomorrow.

[John Donovan]

Ok, no worries, Karen sent me a very nice test file with Xe and La!  From this I was able to find the problem and fix it!

If you download the latest PFE update you both will now be able to specify interference corrections on elements that are utilizing the virtual standard intensity feature!
john

[Philipp Poeml]

Hi John,

I downloaded and updated from http://www.probesoftware.com/Update.html but apparantly it was still an old version from Feb 11. Now I am checking one of the ftp sites. Do you know where usually the latest version is kept?

Cheers
Philipp

[John Donovan]

I downloaded and updated from http://www.probesoftware.com/Update.html but apparantly it was still an old version from Feb 11. Now I am checking one of the ftp sites. Do you know where usually the latest version is kept?

Did you download the PFE update ZIP?  Sorry, I didn't update the ZIP last night, just the ProbeForEPMA.msi file.  Try downloading the msi file instead...

[Philipp Poeml]

Everything is fine. I found the update zip on the ftp whitewater.uoregon.edu. That worked out.

Thanks for implementing this overlap correction thing. For us this will be very helpful in the future!

[wrigke]

I just updated and will hopefully give it a try tomorrow.  Thanks so much for doing this!

Karen

[John Donovan]

Here is an updated screen shot of the virtual standard intensity dialog showing Philipp Poeml's virtual standard calculation for Am Ma using Pu and Cm actual standard intensities as calibration points:



I guess this means that he has plutonium and curium standards, but no americium standard!

By the way, I'm reading the new book "The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements".  It's a good read, lots of element trivia.  Some I already knew of, but a lot I didn't.

https://www.amazon.com/Disappearing-Spoon-Madness-Periodic-Elements/dp/0316051640

[John Donovan]

Here's a tip for using the virtual standard feature in PFE:

After peaking up on your two measured elements, note the actual spectrometer position "offsets" from the theoretical positions as shown in in log window:

On and Off Peak Positions:
ELEM:    sr la   rb la   si ka   al ka
ONPEAK 78416.0 28465.0 81309.0 32482.0
OFFSET 27.2891 23.2559 145.617 -16.029
HIPEAK 83343.8 29779.5 82225.8 34493.1
LOPEAK 74070.1 24666.4 80342.0 30718.9
HI-OFF 4927.80 1314.50 916.797 2011.08
LO-OFF -4345.9 -3798.6 -967.00 -1763.1

Clearly these offsets are for a Cameca instrument!

Then apply the average of the offsets for the two measured elements utilized for the virtual measurements, and then apply that offset value to the virtual element spectrometer position.  The idea being that if the two measured elements on that spectrometer are offset by say 10 units, then the spectrometer position of the virtual element (in between those two elements) will also probably be offset by the same amount.