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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Roberto Ribeiro de Avillez
Professor Associado
Pontifícia Universidade Católica
Dept Engenharia de Materiais
tel. 55+ 21+ 3527 1250
e-mail: avil...@puc-rio.br
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