[Ifeffit] N-idp

Silvio Levy levy at msri.org
Mon Mar 19 12:36:48 CDT 2007

Hi Shan, here's a somewhat different way to reach the same conclusion
as Scott.

>scan during data collection? As I see Nidp = (2/pi)*(deltak * 
>deltaR), there is no reference to the scan step.

But there is, an implicit one.  Your deltaR is limited by (among other
things) the scan step.  If you halve the scan step, you can in
principle look twice as far in R space.  The problem is, because of
the nature of the EXAFS equation, there isn't any signal beyond (say)
R=15 AA that's not completely drowned by noise.  So there is a point
beyond which it's not useful to sample more finely in k space.

Of course, below that point, the step size in k space does matter.


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