[Ifeffit] LCF

[Jason Gaudet]

It depends how you want to set up your guess-def-set parameters.  For
argument I'll describe a system of BCC Mo metal and MoO3, where you want to
determine what fraction of Mo is in each.

My usual method is just to set each path as N=1, SO2=amp_O for Mo-O, and
N=1, SO2=amp_Mo for Mo-Mo.

Then, in guess-def-set, I'd GUESS
N_Mo = 8
N_O = 6
SET (SO2 as determined by my standards)
so2=0.87
and DEFINE my amplitudes
amp_Mo = N_Mo*so2
amp_O = N_O*so2

(And of course you want all the other parameters as well, I'm just showing
the amplitude ones.)

Then, once I get my N_Mo and N_O I can scale these to my expected
coordination numbers and see if I get reasonable contributions for each.
(Is N_Mo/8 + N_O/6 = 1?)

If I had a really good reason to believe all Mo metal in my sample had an
average Mo-Mo coordination of exactly 8 and all Mo oxide had an average
Mo-O coordination of exactly 6, I could define things another way.

SET
N_Mo = 8
N_O = 6
so2=0.87
DEFINE
amp_Mo = N_Mo*so2*Frac_metal
amp_O = N_O*so2*(1-Frac_metal)
GUESS
Frac_metal=0.5

And that constrains all the amplitude parameters so the only result is what
atomic fraction of Mo is present in the metal phase.

Makes sense?

-Jason

On Thu, Nov 7, 2013 at 2:05 PM, KONG Qingyu <
qingyu.kong at synchrotron-soleil.fr> wrote:

> Hello Jason,
>
> Thanks a lot for your reply.
>
> What I can get from Artemis is the fitted parameters (amp, enot, ss^2,
> delr) of each path, Mo-O, Mo-Mo, how can one get the percentage of Mo, x
> from  Li2MoO3 and 100-x from MoO3, from the fitted information.
>
> Best regards,
>
>
> Qingyu
>
> Beamline ODE
> Société civile Synchrotron SOLEIL
> L'Orme des Merisiers
> Saint-Aubin - BP 48
> 91192 GIF-sur-YVETTE CEDEX
> Tel: +33 (0)1 69 35 97 84 (office)
>       +33 (0)1 69 35 97 16 (beamline)
> email: kong at synchrotron-soleil.fr
>
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