From: Alexandra Seclaman <seclaman_alexan...@yahoo.com>
Subject: RE: Configuration of PANalytical X'pert Pro
To: rietveld_l@ill.fr
Date: Monday, November 30, 2009, 2:05 PM
Thank
you for all of your answers, it was more than I hoped for.
I did a Rietveld refinement on stibnite (Sb2S3). And I
mesured it from 5 2theta to 90. But from 5 to 20 2Θ i
had a serious background noise and general trend similar to
that of glass. This trend and the background noise are there
no matter what I measure.
I can't get to the lab until Wednesday, but from what I
recall, from the X ray source to the X'celerator
detector: there are 1/4 +1/2 fixed divergence,the widthest
mask and the slit (i'm not shure if that is the proper
name) in front of the X'celerator is also the widthest.
The automated system of "handling" the sample is
installed, should i changed it?
And I forgot to mention, the system is MPD.
I can give you more details on Wednesday.
I'm sorry for my not technical terms, but is very hard
for me
to speak about diffraction in English.
Alexandra Seclaman
seclaman_alexan...@yahoo.com
a.c.secla...@gmail.com
--- On Sun, 11/29/09, Tony Raftery
<a.raft...@qut.edu.au> wrote:
From: Tony Raftery <a.raft...@qut.edu.au>
Subject: RE: Configuration of PANalytical X'pert Pro
To: "Alexandra Seclaman"
<seclaman_alexan...@yahoo.com>
Date: Sunday, November 29, 2009, 11:57 PM
Alexandra,
while there is no such thing as a standard configuration,
choices can be made to help in the modelling. Another
corresponant (to the Rietveld list) made some
suggestions that I only partly agree with. A lot depends on
you goals ans available instrumentation - for instance if
you have an X'cellerator detector and a monochromator.
If you are interested in the low angle region (as I think
you are) or not. If you were looking at some phases or
phases where the peaks began after
25 deg 2theta, you could afford to go to larger divergence
than if the peaks started at 5 deg 2theta.
I see little use for beam knifes except over restricted low
angle ranges (they always interfere at high angle, where
they interfere depends on how they are set). It see little
use for varable divergence slits for all sorts of reasons
(firstly as there is no rock solid conversion from automatic
to fixed intensities, secondly the resolution changes with
angle with variable slits that can't be modelled -
unless a more sofisticated model than that of Highcore Plus
is used).
What I agree with is that you need to use and properly
adjust the anti-scatter slits.
Fro memory (I am away from the lab for a few weeks) my
conditions are for scans 3.5 deg to 140 deg 2theata - a
general scan, well crystalled phases
fixed divergence 0.5 deg, a-scatter (incident) 1 deg,
sollers (incident) 0.04 rad
3.4mm (diffracted) a-scatter, mono fot
X'cellerator, X'cellerator set full )about 2 deg)
step 0.02 deg (or what X'cellerator allows, in my case
0.0167 deg), step-time to give about 10,000 counts full
scale
________________________________________
From: Alexandra Seclaman [seclaman_alexan...@yahoo.com]
Sent: Saturday, 28 November 2009 3:09 AM
To: rietveld_l@ill.fr
Subject: Configuration of PANalytical X'pert Pro
Hello,
I have done a Rietveld refinement using a PANalytical
X'pert Pro but the standard configuration is giving me a
lot of troubles. This configuration is somewhat
"blind" to the small 2 theta angles and it
introduces (because of the poorly focused X ray beam) a
heavy background. I've manage to remove that background
by refinement but I'm sure that the quality of the
acquisition can be improved.
I am no engineer, so the inner workings of that machine are
somewhat a mystery to me. I am asking if someone else has
used a PANalytical for Rietveld and if you can give me a
better configuration of slots, masks etc. I have tried
different configurations with no success.
Please take into consideration, while writing your reply,
that I'm still a student and I have yet a lot to learn.
Thank you!
Alexandra Seclaman
seclaman_alexan...@yahoo.com
a.c.secla...@gmail.com
