[Ifeffit] Re: Amplitude and the EXAFS equation

[Bruce Ravel]

Hi all,

Matt mentioned, but didn't expand upon, yet one more important
aspect of the difficult situation of measuring amplitudes in EXAFS.
As he pointed out, all of the effects that Matt, Scott, and I
discussed are *amplitude* effects.  By careful consideration of all
these issues, one may obtain coordination numbers to within 10%.  In
many situations, a sober estimation of uncertainty in coordination may
be quite a bit higher that 10%.

Note, though, that none of these issues are highly correlated with the
phase terms in the EXAFS equation.  Specifically, uncertainty (even
large uncertainty) in amplitude does not mean that you cannot measure
bond lengths precisely.

Even if your coordination numbers are highly uncertain, your delta_R
numbers may have nice, tight error margins.

B


-- 
 Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
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