Congwu,
If you can move the detector the radius of the silicon rings will change
according to the distance and Bragg angles. Moving the sample might be easier
for the same check. Does your spurious ring move so that you can trace it back
to a point inside the sample? Could it come from the collima
If you've eliminated the possibility of target or sample impurities, the
so-called Renninger Reflections would also be my guess. However, I also don't
have the (picture of) data to observe.
If the "continuous ring" [re: Andrew Payzant below] refers to a transmission
photo of a powder, then i
Thank you very much, Prof. Stephens, my mailing address is bellow.
Congwu Cui
*
Department of Physiology and Biomedical Engineering
Alfred 2-404, Mayo Clinic College of Medicine
200 First Street SW
Rochester MN 55905
phone: 507-
For some reason the original email never made it to me so I can't see the data
- so apologies if this is way off base. However, it's not impossible for
perfect single crystal material to produce forbidden reflections from multiple
diffraction effects if the crystallites are big enough.
Pam
_
Peter,
That is my guess too either additional (weak) characteristic lines such as
Mo-K beta, or contaminant lines such as W L, or, as you point out, some
wavelength in the Bremmstrahlung that meets the Bragg condition for some
silicon crystallites.
However, I would not have expected a few large
I'll mail you some fine Si powder if you send me your address.
My best guess is that you have a relatively big lump of Si in your sample
that happens to be lined up to make a bright spot from the bremstrahlung
part of the spectrum. It happens to meet some Si Bragg reflection
condition for some
Under such conditions (large crystallites) you need to consider additional
possible wavelengths the other (often ignored) spectral lines from Mo,
plus the range of W spectral lines (due to W contamination of the anode from
the filament).
Andrew
--
E. Andrew Payzant
Senior R&D Staff Member
High
