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@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

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