Actinide analysis

[Probeman]

Question on trace Pu in Uranium: when you actinide people analyze trace Pu (Ma) in U, on a PET WDS, can you easily resolve the lines or do you need an interference correction?

[Philipp Poeml]

Pu Ma in U is quite hopeless, we do not do that. U Mb is in the way, the correction is enormous. We do Pu Mb in U, and still we have to correct for U M3-N4 and a bit of U Mg.

We only use Pu Ma when there is also Am and Cm, because then Pu Mb is totally hopeless....  Cm Ma in right on top.

We use a Qtz 10-11 crystal though with a bit better resolution. PET gives more counts but the lines are a bit closer together. And we have a Rowland circle of 180 mm which also helps. But in the good old days, on the MS46, we had 220 mm, that was really good...

[Probeman]

Thank-you for the explanation.

Is it possible to do the Pu La line? The L edge is ~23 keV but at 30 or 40 keV is it possible to excite it enough? Basically the user has ~1 um uranium particles and they want to detect trace Pu with an SEM.

Maybe microXRF is the way to go?  I note that this detector is available from Bruker:

https://www.bruker.com/en/landingpages/bna/xtrace.html

[Nicholas Ritchie]

When you say trace, what do you mean?  This is a difficult problem and high traces might be possible but WDS-level traces aren't going to happen.  I'm not sure that XRF will help.  XRF might have better trace sensitivity but there is still the tiny signal from Pu that needs to differentiated from the large signal from U.  DTSA-II simulations suggest that 1 mass % Pu can be measured using e-beam EDS and measured standards but 0.1 mass % is a challenge using the M lines at 12 keV.  Even at 30 keV, the L lines are relatively weak and getting the dose necessary to see the Pu will be a challenge.  The Pu LA1 is barely visible at 1 mass%.  Regardless, you'll need doses of at least 1200 nA*s (for a typical detector area/geometry).

[JonF]

... the user has ~1 um uranium particles and they want to detect trace Pu with an SEM.

Maybe microXRF is the way to go?  I note that this detector is available from Bruker:

https://www.bruker.com/en/landingpages/bna/xtrace.html

We've got an XTrace (1) on our Quanta, and the spot size is ~ 30um diameter, assuming the sample is mounted perpendicular to the X-ray beam. The X-ray beam will hurtle straight through a 1um particle, too. 

[Probeman]

... the user has ~1 um uranium particles and they want to detect trace Pu with an SEM.

Maybe microXRF is the way to go?  I note that this detector is available from Bruker:

https://www.bruker.com/en/landingpages/bna/xtrace.html

We've got an XTrace (1) on our Quanta, and the spot size is ~ 30um diameter, assuming the sample is mounted perpendicular to the X-ray beam. The X-ray beam will hurtle straight through a 1um particle, too.

With a 50 keV x-ray source that is a given.  I'm just wondering if using that XTrace and the U and Pu L lines, the researcher could obtain good sensitivity for trace Pu in U in 1 um particles.

At least there would be no matrix corrections to speak of!