Dear Yuan,

These electron blobs will act as repulsive potentials for photoelectrons.

To estimate (at least roughly) the value of the influence of these potentials on EXAFS signal you can approximate the electron density for the blob with some simple spherically symmetrical function, then find the potential created by this charge distribution and then calculate backscattering and forward scattering amplitudes according to any textbook on quantum mechanics or scattering theory. Then compare your results with scattering amplitudes calculated for some light atoms by e.g. FEFF

The backscattering amplitude tells you about single scattering contribution. Forward scattering amplitude tells you about possible contribution to chain scattering if the last presents in that atomic structure.

Victor Krayzman

From: "Yuan Ping" <ping2@llnl.gov>
To: "XAFS Analysis using Ifeffit" <ifeffit@millenia.cars.aps.anl.gov>
Sent: Monday, February 6, 2012 2:57:16 PM
Subject: [Ifeffit] XAFS for electride

Dear XAFSers,

Recently there has been a growing interest in the electride phase of sp-bonded materials at extremely high pressures >Mbar (see attached paper for example). This phase is characterized by a matrix of positive ions and interstitial electron blobs. I am wondering how XAFS signal would change when these electron blobs are present. The x-ray diffraction probably won't detect them directly. But XAFS might be able to show their existence if they behave like additional scattering centers.

Any thought or information would be appreciated.

Yuan

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