Roberto R. de Avillez napisał(a):
Hi Lukasz,
You are talking about fundamental parameters approach to Rietveld as
proposed by Alan Coelho (CHEARY, R. W. e COELHO A., J. Appl. Cryst.,31,
1998, 851-861. ) The sample length is the length of the sample measured in
the axial direction (in mm). It is the illuminated area, so it must depend
on the source length if you consider the axial divergence. I usually fit
all the fundamental parameters using a diffraction from a standard sample
and making restrictions for the allowed variations. Then I use the fitted
values as the instrument parameters for my samples that use the same
geometric arrangement.
Best regards,
Roberto de Avillez
Łukasz Kruszewski escreveu:
Hello to all!
My name's Lukasz Kruszewski, my interest recently is the mineralogy of
burning coal dumps. I'm trying to obtain the unit cell parameters of some
members of the alunite group, analysed on Bruker D5005 diffractometer (Co
Ka, Bragg-Brentano, RS = 0.6mm wide, FDS = 1 deg.) with use for an
article. I pack powdered samples as thin layer on a glass slide with
limiters. I would like to kindly ask for help in understanding well the
FULL AXIAL MODEL in the INSTRUMENT section of TOPAS program. I know that
the SOURCE LENGTH, SAMPLE LENGTH and RS length should be FIXED, but I
don't know actually does the SAMPLE LENGHT means. Do I understand well
that its the length of the beam focusation area only, or the whole length
of the glass slide, or the 'working' distance between source and
detector?
I would be grateful for any tips (-:
With best regards,
Lukasz Kruszewski
Instutite of Geochemistry, Mineralogy and Petrology
Faculty of Geology
University of Warsaw
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Muchos Gracias Roberto! You have helped me very much!
Good luck in Your work!
Cheers,
Lukasz K.
