Dear John,
Not really Rietveld related but well ;-)
Since you used Silver Behenate, you have to create a "Calibration
file"containing the d-spacing (in Agstroem) of the rings you will use for
calibration.
Assume you have collected the 3 first rings of Silver Behenate, you will
create a file containing the three following lines,
58.380
29.190
19.40
Let's name this file AgBeh_1-3.cal
Then when launching Fit2d, you choose first the "Powder Diffraction"menu,
Load your file using the "Input" button, then go to "Calibrant" menu,
Choose the "User Defined"option. There you select your file AgBeh_1-3.cal
(check that the directory is properly given).
At this stage, you will reach a menu where you give the pixel size of your
detector, the wavelength, and starting values for the refined parameters
(sample to detector distance, tilts angles), and the parameters you want to
refined.
Then you have to "click" some points on the first ring of your data (by
first, I mean the ring corresponding to the fisrt d-spacing given in your
Calibrant file)
If everything was OK (not too bad starting values), you should get good
refined values : generally sample to detector distance, beam center values
and, if you have choosen this option - tilt values.
This is these values which will be used to further process you SAXS data.
Hope it helps.
Do not hesistate to contact me dircetly if you need further help.
Francois
At 10:17 19/07/2007 +0000, you wrote:
Dear all,
I've got some SAXS data that needs looking at, but i've
forgotten how to calibrate "fit2d" to give the proper
d-spacing. Any help most welcome!!
Silver behenate was the calibrant.
John O'Callaghan
John O'Callaghan,
Materials and Supercritical Fluid Section,
Chemistry Dept.,
University College Cork,
Ireland.
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