And here is the dataset for Ge Ka:



This plot causes me to suspect that the electron beam energy on my Cameca SX100 at ~11 kV is slightly higher than the nominal value would indicate...  what do you all think?

Again, both the Ti and Ge pure metals were freshly polished and uncoated (though well grounded).

Somebody asked about the counting times and beam current for these over voltage curve measurements and so I checked and they were 120 seconds on-peak and and 120 seconds off-peak at 100 nA.

Note that I used freshly polished pure metal standards for these tests, but in case ones samples are carbon coated, one can calculate the electron beam energy loss with a 20 nm carbon using the CalcZAF app and here is is for 5 keV:



So we're losing about 14 volts out of 5 KV. And here at 12 KV:



So only about 8 volts at 12 KV.  But I would still stick with freshly polished pure metals for these over voltage curve tests...

Up until the day he passed, Joe Goldstein used a natural Schreibersite included in a nickel iron meteorite as a P standard for meteoritic phosphides.  He maintained that the P was stoichiometric in Schreibersite, so just knowledge of the Fe,Ni ratio was the only thing that needed to be determined (not a very big effect anyway).  I don't know which meteorite he used, but it was (and still is) in his own mount along with Fe, Ni, and Co pure metals.  As PKa originates from a transition involving the valence band, the peak position changes substantially compared to phosphates.  Probably a peak shape effect too, so using an actual (FeNi)phosphide is undoubtedly a little better than just using a phosphate standard and then updating the peak position on the unknown phosphide.  I know the community is throwing a lot of shade on these sorts of 'internal' laboratory standards, but one might say that Joe did okay.

You just identified one of the many problem with using "internal standards".    They are difficult if not impossible to reproduce!   How is Colin to obtain Joe's standard? 

I'm sure that Joe did a great job using this standard and I might even accept his assurance that the P is stoichiometric, but then there's the issue you mentioned with the Fe/Ni ratio, so yet another problem!

I think Colin is exactly correct to seek a high purity synthetic that matches the valence of his sample.  Come on people, let's go global and source these high purity synthetics...

Well deserved shade perhaps!   

Hi;
we are analysing some meteorite samples and have encountered a nickel phosphide (Fe,Ni)3P mineral want to use Fe3P as a standard.  Can anyone help with getting a single crystal of this material, synthetic for preference.  I have tried all the usual crystal growers and have not identified any.  We did at one stage try and purchase a Fe3P MAC standard but this is no longer available?

Why not use highly available GaP as standard for P?

We're slightly adjusting the duration of the webinar presentations tomorrow morning (10 AM US Pacific Coast time).

Anette's talk on PictureSnap/PictureSnapApp will be a little shorter and my talk on trace elements will be slightly longer (just too much material to talk about regarding trace elements!):

Our next Probe Software webinar featuring presenters Anette von der Handt and John Donovan is this Wednesday, the 15th.  Click the link here to receive an invitation to this Zoom webinar:

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and join us by Zoom Wednesday May 15, 2024 at 10am PDT for 2 presentations featuring:

10:00 AM to 10:30 AM (30 min) Using PictureSnap and PictureSnapApp for advanced sample navigation and documentation by Dr. Anette von der Handt, University of British Columbia, Vancouver

10:30 AM to 10:40 AM (10 min) "Break"

10:40 AM to 11:30 AM (50 min) High sensitivity, high accuracy trace element analysis by John J. Donovan, University of Oregon/Probe Software. Inc.

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