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Charles,

I assume this was slider cal’d.? Why is Fe escape in the Am button? Or are these 2 different buttons?? What Am energy is it? This is quick and dirty but can still miss a lot of stuff.? You assumed ?Y, Nb and Zr but didn’t look any further at each individual peak to validate the assumption The Fe Ka1 and weak Kb ?shows there is Fe there. The peak between the Am and Fe esc looks like La la1. That would need to be confirmed with the higher energy Ka which it doesn’t look like you did or maybe you did, I can’t tell from the plots. The question is what would La be doing in a Fergusonite /cyrtolite? Is it even there?? I understand using tabs for interferences and a quick look but it’s essential to look at everything on an individual peak energy basis which will help or eliminate your hypothesis.

Thanks for the nice run though I can see your method and approach.

dud

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From: [email protected] [mailto:[email protected]] On Behalf Of Charles David Young
Sent: Sunday, March 8, 2020 8:34 AM
To: [email protected]; Mike Loughlin
Subject: [XRF] DppMCA vs Theremino

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Based on Dud's encouragement I will try and use DppMCA for analysis.? To be clear, I tried it previously when I first got the Amptek system and got discouraged.? I'll give it another try and document it in a subsequent email.

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First though I wish to give a quick demo of how I use DppMCA for acquisition and Theremino for analysis.? I will make it as simple as possible.? I will both embed the images as well as attach them because some people have better luck with one or the other.? If you download the attachments and put them in a folder you can scroll through the images as I describe the steps.

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Step 1: acquisition

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The target is a small specimen that has some nice little fergusonite crystals associated with zircon cyrtolite.? Because it does not present the ideal geometry it took an overnight run to collect the data.

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Step 2: import into Theremino

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I modified Theremino to recognize the .mca format and import the data with no processing other than to draw it on the screen using the available resolution.?

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Step 3: turn on reference labels

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Because of the Am241 source and its shielding there are many peaks that I wish to be aware of so that I can ignore them most of the time.? This creates some temporary clutter but it allows me to quickly determine which peaks are really of interest.

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Step 4: zoom in on region of interest

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It is immediately apparent that there are 3 large peaks that don't align with any of the reference peaks.? I zoom in on those to reduce the clutter.

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Sometimes we are not so lucky such as the case of Fe which is present in the Am241 button.? In this case I am pretty sure it is not a major element of the specimen.? If the Fe peak were much larger I would assume differently.

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Step 5: identify the Nb peak

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I use my mouse to double click on the largest peak.? The id label NbKa1 appears over that peak and the NbKa2 and NbKb1 labels appear at the same time.? Having these labels toggle on and off as a set allows me to quickly evaluate the validity of an id.? In this case all 3 peaks look reasonable so I will assume with confidence that Nb is present in this mineral.

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Step 5: identify the Zr peak

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I double click on the next highest peak.? Once again all 3 peaks align nicely with Zr, even though the ZrKb1 label is a little obscured.? I'll clean that up later.? Zr is definitely also present.

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Step 6: identify the Y peak

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I double click on the last large peak and the Y identity labels appear.? The YKa1 and YKa2 peaks line up precisely so this is also looking good.? The YKb1 peak is a little more subtle because it is so close to the NbKa1 peak.? They are so close in fact that when both Nb and Y are present their peaks add together to make an extra large peak.? The presence of the YKb1 peak is betrayed but the bulge on the right side.? Once again I can say with confidence that Y is present.

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Step 7: declutter and document

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There are no other major peaks of interest so I can turn off the reference labels and document my results in the text box on the left.?

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This whole process took perhaps 2 or 3 minutes. Luckily I was able to identify all the elements necessary to justify this mineral identity.? Typically there are many other elements present and it can take a little longer.? If the elements don't match the mineral formula very well further research is sometimes necessary to clarify the id.

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