Whoops--it helps if I actually read the formula that the person actually wrote.
--Scott Calvin Sarah Lawrence College On Jul 16, 2008, at 3:40 PM, Bruce Ravel wrote: > On Wednesday 16 July 2008 15:27:27 Scott Calvin wrote: >> Bruce--I'm not following your critique of the third panel. Where's >> the >> confusion? I see the disorder term, and I see the mean-free path >> term, >> but I don't see them inappropriately labeled or confused with each >> other (aside from the common use of "Debye-Waller factor"). Unless >> perhaps it's just that the spacing and arrows in the label "From ab- >> initio calculations or from reference compounds" is confusing? (i.e. >> it kind of looks at first like the slide claims that the mean-free >> path comes from a reference compound) > > Unless you redefine sigma^2 such that it has units of 1/angstrom^2 and > it subsumes the 2 we usually put in that exponential, the expression > > exp( -k^2 / sigma^2 ) > > is incorrect. I concur that one is always free to define ones terms. > But redefining what sigma means in the exafs equation can only lead to > confusion. > > (BTW, When you analyze your data by comparison to an empirical > standard, I would presume that the mean free path is considered to be > chemically transferable.) > > B > > _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit