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
