[Ifeffit] Question about XAFS resolution

[Matt Newville]

Hi Shoaib,


On Wed, Jun 25, 2014 at 7:34 AM, Shoaib Muhammad <mshoaibce at gmail.com>
wrote:
>
> Dear Matt Newville,
>
> Sorry to disturb you by asking one question, hopefully you will mind it.

Asking on the ifeffit mailing list is generally better.  I am CCing this
reply to that list.

> I often see that resolution XAFS spectrum of K-edge and especially
pre-edge is good for
> 3d transition metal but comparatively 4d transition metal XAFS spectra
and its pre-edge
> spectrum is poor. Is it due to low energy resolution at higher energy
level at synchrotron
> source or something related with electronic transitions? because as far I
understand
> pre-edge in 3d transition metal is due to 1s-3d and 4d metals is 1s-4d.
>

The energy resolution is a convolution of monochromator energy resolution
and natural
line-width of the core electronic level.  Generally speaking, for K edges
below 10 keV or
so, Si(111) and the core-level widths are comparable, ranging from ~0.5eV
to 2 eV.

Both the mono resolution and core-width increase with energy,  but the
core-width increases
quadratically and so tends to dominate at higher energies (say, above 20
keV).

Core level widths for L3 edges are about 2x that of K edges, so that this
term almost always
dominates for L3 edges.


> I am student in Sungkyunkwan University (Korea) and a beginner of XAFS.

Cheers,


--Matt
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