Hi all,
I wonder if the error is due to the sample stage, i.e. error present
when capillary is used but not for horizontal sample stage (rotating table)?
-Markus
--
Dr. Markus Valkeapaa
Department of Chemistry, Helsinki University of Technology
P.O. Box 6100, FI-02150 TKK
Office: Kemistintie 1, room B206
tel: +358 50 511 3073, +358 9 451 2596, +358 44 290 2515
fax: +358 9 462 373
email: markus.valkea...@tkk.fi
--
Peter Y. Zavalij kirjoitti:
Kurt,
It looks like incorrect step size (difference between actual step size
and one that is written in the file) or incorrect distance to the
detector. The later may incorrect step size if detector is PSD.
I have similar situation with much smaller difference in peak position
but the shift (difference between actual and written step size) varies
from measurement to measurement. Bruker is working on this but so far no
solution/cause is known.
Your case may be simpler if the difference is constant. Perhaps
calibration of detector or its distance to the sample is needed.
Best,
Peter Zavalij
X-ray Crystallographic Center
University of Maryland
College Park, MD
Office: (301)405-1861
Lab: (301)405-3230
Fax: (301)314-9121
*From:* Kurt Leinenweber [mailto:ku...@asu.edu]
*Sent:* Thursday, January 08, 2009 6:09 PM
*To:* Rietveld_l@ill.fr
*Subject:* error in peak positions that is linear in theta
Dear Rietvelders,
(I hope this list is appropriate for this question). I am trying to set
up a new D8 diffractometer from Bruker, and have it set up with a Vario
monochromator focusing on a sample in a capillary. Of course I hope to
do Rietveld refinement on the samples eventually. But there is an error
in two theta of the peak positions on all samples, and the error is
linear in two theta. At 40 degrees the error (measured minus expected)
is about 0.020 degrees, at 80 degrees the error is about 0.040 degrees,
etcetera.
Has anyone ever seen anything like this and do you know where it could
come from?
Thank you very much,
- Kurt
*********
Kurt Leinenweber
Dept. of Chemistry and Biochemistry
Arizona State University
Tempe, AZ 85287-1604
phone (480)-965-8853
fax (480)-965-2747
***********
