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

[Bruce Ravel]

On Wednesday 14 April 2004 04:27 am, Stanislav Stoupin wrote:
> As for the correlation between Ru-O variables and the background
> parameters, they are somewhat correlated I think

Stanislav,

I think you will have to live with correlations between the oxide and
the background.  That is the flip side to my suggestion that you just
treat the oxide as the background. (Which you and Carlo clearly
explained is an undesirable thing to do.)  The oxide has low frequency
Fourier components and its spectrum leaks into the very low-R rang.
The background spline has very low frequency components and its
spectrum leak into the higher-R range.  Consequently, it is hard to
them apart.  Oxides are "fun" that way. ;-(

Would it help to impose reasonable but unvalidated prior constraints
to the fit?  You largest oxide/background correlations involve the
oxide delta_R value.  Perhaps it would be prudent to fix the R of the
oxide to what you expect from bulk ruthenium oxide.  That may be
slightly wrong, but it might help shore up the fit.

B

BTW, Does the new release of Artemis seem to address the many problems
you reported with your multiple data set, multiple feff calculation
fits?


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