In my experience, it is best to stay away from sulfate which has a hugely
intense peak subject to self absorption. At SSRL, we advice users to choose
Sodium Thiosulfate with the low lying and sharp S-S sigma star peak at
2472.02 eV and Tetraphenyl phosphonium bromide at 2146.96 eV
Hi Mike, Matthew,
On Thu, May 7, 2020 at 5:55 PM Mike Massey wrote:
> I agree Matthew, I also tend to use the primary K-edge peak for P
> calibration, but one issue to be wary of is attenuation/flattening of the
> primary peak (if one is using a concentrated sample).
> Gypsum sounds like a
Hello, all. It's been a long time since I've been in touch. Yes, energy
calibration is always an issue. Its especially important for lower-Z XAFS.
I feel that edge and transition energies should be recorded, but depending
on the beamline and facility the absolute calibrations are hard to
I agree Matthew, I also tend to use the primary K-edge peak for P calibration,
but one issue to be wary of is attenuation/flattening of the primary peak (if
one is using a concentrated sample).
Gypsum sounds like a good material to use for S, since it is commonly available
and probably not too
For elements like P and S, people often use the energies of peaks.
These are more immune to noise, energy-resolution effects and
overabsorption than inflection points are. For instance, on ALS 10.3.2,
I used the sulfate peak of gypsum set at 2482.74eV. I forget where I
got that number.
Indeed, in my experience (which is limited to one beamline at one synchrotron
facility for P XAS), once it is calibrated, the energy selection tends to be
quite stable, so I think you're on-target there.
The trouble I still run into, though, is comparability of data between studies.
On Tue, May 5, 2020 at 10:56 PM Mike Massey wrote:
> On a tangentially related topic, I find that phosphorus K-edge XAS energy
> calibration conventions are still in a bit of a "Wild West" state, with a
> wide variety of materials and values in use for energy calibration. As an
On a tangentially related topic, I find that phosphorus K-edge XAS energy
calibration conventions are still in a bit of a "Wild West" state, with a wide
variety of materials and values in use for energy calibration. As an extreme
example, one or two frequently cited papers in my field from the
We are wondering if others agree that the reported values for the W L3 and W L2
edges are incorrect. We recently noticed the following:
The "Edge" - defined by the inflection point of the absorption edge step
When using the Ir L3 edge (11215.0 eV) as a calibration, the W L3- and L2-edges
Kraft, S., Stümpel, J., Becker, P., & Kuetgens, U. (1996). High
resolution x‐ray absorption spectroscopy with absolute energy
calibration for the determination of absorption edge energies. Review of
Scientific Instruments, 67(3), 681-687.
has precision measurements of a bunch of
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