Author Topic: unidentified peaks in WDS scan on Al2O3  (Read 1056 times)

AndrewLocock

  • Professor
  • ****
  • Posts: 78
    • University of Alberta Electron Microprobe Laboratory
Re: unidentified peaks in WDS scan on Al2O3
« Reply #15 on: April 01, 2022, 12:57:40 PM »
This peak at ~1.025 keV is not a diagram line, not a satellite line, not a RAE line, and not a higher-order diffraction line.
It does not appear to be a multiple diffraction line (Renninger effect).
It is observable on Zn, Mg, Al, Si, and Zr elemental reference materials.
In these materials, it occurs at a fixed fraction of the energy of the principal diagram line of each element.

I would be very interested to know if others have observed this with TAP-crystal spectrometers.

This unidentified peak on TAP is closer to the F Ka peak so maybe or maybe not related:

https://probesoftware.com/smf/index.php?topic=992.0

The peak for fluorine, 0.6768 keV, on TAP should be at 71130 or so in units of 100,000 sine theta.
This is not close to what I have observed in pure MgO and in pure metallic Mg.

Thanks, Andrew

Probeman

  • Emeritus
  • *****
  • Posts: 2384
  • Never sleeps...
    • John Donovan
Re: unidentified peaks in WDS scan on Al2O3
« Reply #16 on: April 01, 2022, 06:49:44 PM »
This peak at ~1.025 keV is not a diagram line, not a satellite line, not a RAE line, and not a higher-order diffraction line.
It does not appear to be a multiple diffraction line (Renninger effect).
It is observable on Zn, Mg, Al, Si, and Zr elemental reference materials.
In these materials, it occurs at a fixed fraction of the energy of the principal diagram line of each element.

I would be very interested to know if others have observed this with TAP-crystal spectrometers.

This unidentified peak on TAP is closer to the F Ka peak so maybe or maybe not related:

https://probesoftware.com/smf/index.php?topic=992.0

The peak for fluorine, 0.6768 keV, on TAP should be at 71130 or so in units of 100,000 sine theta.
This is not close to what I have observed in pure MgO and in pure metallic Mg.

Thanks, Andrew

Yes, I understand. 

I'm just wondering (though they are at different sin thetas), if the mechanism that produces a spurious peak on my TAP crystal only on Ti, is related to the mechanism producing the spurious peak on your TAP only for Mg.

Maybe do a similar scan on Mg and see if you can reproduce the spurious peak I see near F Ka.
The only stupid question is the one not asked!

AndrewLocock

  • Professor
  • ****
  • Posts: 78
    • University of Alberta Electron Microprobe Laboratory
Re: unidentified peaks in WDS scan on Al2O3
« Reply #17 on: April 06, 2022, 04:27:49 PM »
Quote
I'm just wondering (though they are at different sin thetas), if the mechanism that produces a spurious peak on my TAP crystal only on Ti, is related to the mechanism producing the spurious peak on your TAP only for Mg.

Maybe do a similar scan on Mg and see if you can reproduce the spurious peak I see near F Ka.

I ran a scan on synthetic MgO (20 kV, 300 nA) and only see:
2nd-order peaks of Mg: K-beta, satellite K lines, and K-alpha (attached MgO-20kV-300nA-TAP.jpg).
The range was 60,000 to 80,000 in units of 100,000sin(theta), with 1000 steps and dwell-time of 1 s per step.

I ran some scans on synthetic rutile (from MTI Corp.) at the same conditions over the same range, and just see:
higher-order peaks of Ti (attached TiO2-20kV-300nA-TAP.jpg).

I then ran a set of 10 accumulations on synthetic rutile from 69,000 to 73,000 with 200 steps and dwell time of 2 s per step, at 20 kV and 300 nA.
The attached results have been smoothed (3-point smoothing), and the file is: TiO2-20kV-300nA-TAP-detail-10accumul.jpg

Conclusions: I don't see any anomalous features around 71,000 in these TAP-crystal spectra of MgO or TiO2.
(All of this was in PeakSight software - I was in a bit of a rush).

Cheers, Andrew