[Ifeffit] Feature near edge of Ni XANES spectrum

[Ritimukta Sarangi]

Hello Aditya,
If I understand correctly, the nomenclature you are using is a little
misleading. The sharp feature that you are referring to is a rising-edge
feature and is not after the edge. The is a classic feature for square
planar complexes and Ni does form a lot of those. The origin of this
feature has been argued (in molecular systems) to be either:

1) Valence bond configuration interaction feature (VBCI), which is a
formally forbidden 2 -electron transfer process. It gains intensity with
covalent overlap of metal with ligands and has been shown (in the case of
Cu(III) which is isoelectronic to Ni(II)) to increase with metal-ligand
bond strength.

2) It has also been attributed to longer-range multiple scattering.

It is important to realize that both effect increase in square planar
systems and usually such a feature is the hallmark of a square planar
molecule.
Best,
Riti

On Tue, Feb 9, 2016 at 6:19 PM, Aditya Shivprasad <aps202 at psu.edu> wrote:

> Dear list,
>
> I have obtained nickel XANES spectra (attached) from metallic Zircaloy-2
> nuclear fuel cladding (Zr, 1.5% Sn, 0.15% Fe,  0.1% Cr, 0.05% Ni).
>
> In the spectrum, I identify the edge as being approximately 8331-8332 eV
> (based on maximum of first derivative), as it is for pure Ni. However, I
> also identify a sharp feature at less than 1 eV past the edge. If anyone on
> the list could help me to understand the origin of this feature, that would
> be very helpful.
>
> Thanks
> --
> Aditya Shivprasad
>
> aps202 at psu.edu
> Ph.D Candidate
> Nuclear Engineering Department
> Pennsylvania State University
>
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