Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Ritimukta Sarangi
Hello everyone, 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

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Matt Newville
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

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Trudy Bolin
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

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Mike Massey
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

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Matthew Marcus
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.

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Mike Massey
Hi Matt, 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.

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-07 Thread Matt Newville
Hi Mike, 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 >

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-05 Thread Mike Massey
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

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

2020-05-05 Thread Matthew Marcus
This paper: 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