On Tue, Feb 28, 2017 at 9:48 AM, Bruce Ravel <bra...@bnl.gov> wrote: > > On 02/28/2017 10:10 AM, Samy Ould-Chikh wrote: > >> Dear Ifeffit mailing list, >> >> >> >> I have a question which concern units and I can’t find the answer in the >> Feff manual. >> >> In a FeffNNN.dat output file, what are the unit of the numbers (if any) >> corresponding to >> >> φc, >> >> |Feff|, >> >> φeff, >> >> the reduction factor, >> >> λ, >> >> Re(p) >> > > Samy, > > This is a peculiar reference, but I think the clearest written explanation > of this is in the manual for the ancient "feffit" program. Here is a copy > of its manual: > > http://cars.uchicago.edu/~newville/feffit/feffit.pdf > > You will want to look at page 22. While the rest of the manual is not so > useful anymore (in the sense that there are very few users of the old > feffit remaining), it's explanation of how the feffNNNN.dat files are used > is excellent. > > Eq. 6.1 should clarify how each term is used and what the units are. > Column 1 is, of course, inverse Angstroms. Columns 2, 3, and 4 are > unitless. The two phase terms go into the argument of the sine, thus must > be unitless. The amplitude term is multiplied by N and S02, thus is also > unitless. The reduction factor, as well, is unitless -- it is used in the > computation of the amplitude term in equation 6.1. > > Lambda has units of angstroms, the real part of p (which is the complex > wavenumber used in the Feff calculation) has units of inverse Angstrom. > > I am pretty certain I got all that right. > > I think it would be a good idea to capture all of this information as well > as eq. 6.1 in the Artemis manual. > > HTH, > B > > Yes, the units for the data in the columns are: mag[feff] and red factor: unitless terms for amplitude real[2*phc] and phase[feff]: radians k, real[p]: inverse Ang lambda: Ang
See http://cars.uchicago.edu/xraylarch/xafs/feffpaths.html and http://cars.uchicago.edu/xraylarch/xafs/feffpaths.html#the-exafs-equation-using-feff-and-feffpath-groups --Matt
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
