Good points. At these low energies, an EXAFS range is a large fraction
of the total energy range, so there tends to be a lot of curvature of
baselines and post-edges. True about the 4O 1NN shell that dominates,
but the same happens with As. All the interesting stuff is in the
higher shells. Most data I've seen has been XANES.
mam
On 9/13/2023 12:42 PM, Mike Massey wrote:
In my experience the main difficulties with EXAFS on P (phosphate) come
from two factors (not signal to noise, it's not hard to get a nice
smooth line, but):
1) You've got 4 O atoms, guaranteed, so any other signal will be small
and on top of that very strong signal generated from the first-neighbor O
Unfortunately,
2) You have very limited data range, either due to instrumental
limitations, or due to interference from sulfur
Don't get me wrong I still have some data sitting around and I'd love to
try P EXAFS analysis on it just to try and grasp that brass ring
but...It's not the easiest task ever.
If you want good data quality "scan longer" is always an option. Some
might think it's crazy but I do think I have some P XAS data where I
took 30 or 60 scans, maybe overnight or something. The scans are so
short that repeats are easy.
Hope this commentary is helpful.
Mike
On Sep 14, 2023, at 07:04, Marcelo Eduardo Alves <meal...@gmail.com>
wrote:
Hi there,
I begin by examining phosphorus adsorption by goethite, hematite, and
gibbsite.
Why is it difficult, if not impossible, to obtain EXAFS spectra at the
P-K edge that can be properly used, i.e., spectra with a high
signal-to-noise ratio, especially for dilute samples?
Would it be possible to use arsenic as a phosphorus proxy to get
conclusions from As K-edge EXAFS data that could be extended to P?
Thank you.
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