[Ifeffit] Re[2]: a question about background refinement

[Bruce Ravel]

On Wednesday 14 April 2004 10:32 pm, Matt Newville wrote:
> > I have two e0 parameters in the model that correspond to ru and pt
> > data sets (they are e0_ru and e0_pt)
> > the same e0_ru I use for Ru-O path
> > Typical values that they take are about:
> > e0_pt           =     7.2318013   +/-      1.0171952    (0.0000)
> > e0_ru           =    -9.1526876   +/-      0.7730603    (0.0000)
> >
> > and this is consistent through all data that I have and also their
> > values almost do not depend on whether I use rmin=1.0A or 1.5A
>
> Two e0's that differ by 16eV for metal-metal bonds seems strange.  
> I'd guess that Pt and Ru would be easily distinguished in the fit,
> but also that E0 would not be dramatically different for these.  
> Are you sure there's not something weird going on with these being
> out-of-phase or something??  I could believe it's possible, but if
> you look at the different fit components look in k- and r-space does
> it all seem to add up as you would expect?

I think Stanislav is doing a two-data set fit and these are the e0
values for the two different absorbers.  That wouldn't, then, be so
unreasonable.

B


-- 
 Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
 Code 6134, Building 3, Room 405
 Naval Research Laboratory                          phone: (1) 202 767 2268
 Washington DC 20375, USA                             fax: (1) 202 767 4642

 NRL Synchrotron Radiation Consortium (NRL-SRC)
 Beamlines X11a, X11b, X23b
 National Synchrotron Light Source
 Brookhaven National Laboratory, Upton, NY 11973

 My homepage:    http://feff.phys.washington.edu/~ravel 
 EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/