Dear Francois,
even older XRPD people may be confused by any satellites, especially
when switching from "traditional" instrumentation (e.g. graphite
monochromator + szinti) towards "modern" instruments, my personal
experience ;-)
Thanks for your documents, very helpful. The table containing the
tungsten L series peaks is included in the PROFEX software also, at
least the wavelengths without intensities. One can go to PROFEX menue
Edit-Preferences-Cursors and activate the wavelengths for display with
the spectral line cursor. I typically routinely check the W Lalpha1,
the most intense one, when analysing data from 1D detectors or unknown
instruments.
Regarding traditional peak search software:
Old ones do simply search for any maxima on 2theta and apply Bragg's
law, assuming monochromatic radiation.
But if the instrument is known and the spectral features including
impurities are included in the wavelength model, not only Rietveld
profile refinement can be improved: The convolution-based
("Fundamental parameter") peak model can be used also in a peak search
procedure by independent peak fitting ("Parrish fitting"). Joerg
Bergmann had written an algorithm "EFLECH" in the 1980ies, see
literature [1] at
http://www.bgmn.de/methods.html.
This software EFLECH is now included in the PROFEX software for peak
search, see:
https://www.youtube.com/watch?v=acMK2z7d_QY
Here, spectral impurities can not get misinterpreted, as they are part
of the fit model.
Young people may be interested in Nicola Doebelin's video channel:
https://www.youtube.com/@profextutorials2325/videos
Best regards
Reinhard
Zitat von francois Goutenoire <francois.gouteno...@univ-lemans.fr>:
Dear everyone,
A very nice discussion to help young people in the field of powder
diffraction.
In our case we are the happy user of two "quick and dirty"
diffractometers (no brand of course !)
but with two different radiations : copper and cobalt with
respectively Nickel and Iron K filter + Modern strip detector
Then in order to check for chemical or spectral pollution ? we
combine the both set of data in order to check and explain all the
peaks.
Otherwise, we use Topas V5 to calculate all the tungstene pollution.
Sometimes many with some old X-ray tube (4 years !)
To help you few documents ( sorry some are in french).
https://perso.univ-lemans.fr/~fgouten/Spectral_Pollution
Best wishes François
Le 05/09/2023 à 08:56, Reinhard Kleeberg a écrit :
Dear Luca,
I completely agree with your opinion, and want to add that even for
"trivial" tasks in XRPD like phase analysis and standard Rietveld
refinements the satellites/spectral impurities do cause significant
trouble:
- The K beta and W L satellites of strong peaks of major phases
like quartz, carbonates or cubic structures in geomaterials are
typically not automatically recognized in the standard peak search
procedures and therefore misinterpreted to be K alpha peaks and
added to the peak list. I can't tell you how often I was asked from
colleagues for explanation of such "unidentified peaks", and how
much time people have spent for searching for explanation of such
artefact lines.
- In Rietveld analysis our software must generate the peaks at
least for the measured angular range. Depending on the method how
the software is doing this, we run into problems with the
satellites. If the software generates the reflections from the
positions of K alpha peaks from the start lattice parameters and
the (extended) upper measured angle, K beta satellites of K alpha
peaks outside this angular range will maybe not generated and
remain unfitted in the pattern. If the software generates the peaks
depending on the shortest wavelength in the wavelength profile
(more intelligent approach), the software must generate much more
reflections (with maxima outside the measured angular range) and
all these peaks must be calculated over an extremely broad angular
range. In the case of low symmetry structures with big cells or
disordered structures described by partial structure factors and
the resulting extreme high numbers of peaks, the "extension effect"
will cause significantly prolonged time for calculations, without
any positive effect.
That's why I prefer to use instrumentation with better
monochromatic radiation (monochromators, high energy resolution
detectors) even in the daily business of phase analysis. We do use
our 1D detector Mythen2 with Fe filter (Co radiation) only for
"quick and dirty" measurements.
Best regards
Reinhard
Zitat von Luca Lutterotti <luca.luttero...@unitn.it>:
Dear Habib,
Reinhard is right, and what he explained is exactly what you
observed. Now I would add that I may not define your Bruker clean
and optimised, because for this kind of samples, wafers and
extremely textured thin films, it would be better to have a
monochromator in the incident beam and not a Ni filtered (I would
more say it is a requirement). It was already showed many times in
the past as a monochromator in the incident beam is a necessity
for this materials to avoid all the "physical artifacts" created
by the strong intensity and not clean Kalpha radiation.
Best regards,
Luca
<http://www.unitn.it/>
Luca Lutterotti
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)

Maud: http://maud.radiographema.com <http://maud.radiographema/>
On 4 Sep 2023, at 12:20, Habib Boughzala
<habib.boughz...@ipein.rnu.tn> wrote:
Many thanks Reinhard,
That's exactly what I wanted to say by "I can assure that our
Bruker D8 is clean and optimized!"
Otherwise, in some other cases of well conditioned thin film no
similar phenomenon is observed!
So, yes, it's obviously possible that your point of view is right.
Regards
Habib
------ Message d'origine ------
De "Reinhard Kleeberg" <kleeb...@mineral.tu-freiberg.de
<mailto:kleeb...@mineral.tu-freiberg.de>>
À "Habib Boughzala" <boughz...@yahoo.com <mailto:boughz...@yahoo.com>>
Cc rietveld_l@ill.fr <mailto:rietveld_l@ill.fr>
Date 04/09/2023 11:07:50
Objet Re: Re[2]: [EXT] Re: [External] Re: Step-like basline
Dear Habib,
the phenomenom "satellites or edges" originates from the
diffraction process. The critical parameters are:
- spectral pureness of the primary beam (primary beam
monochromator, tube spectral contamination like W...)
- the use of K beta absorbtion filter (and its thickness)
- the energy resolution ("window") of the detector system.
Even a D8 system may be equipped with different types of
detectors, slits and energy limits can be set differently for an
identical configuration, and quite often satellite peaks may
appear later in the time of use (aging of the tube produces more
W L, Fe filters may corrode and get perforated...). So it is
strictly recommended to check the instrument peridically, by
measuring a full pattern of a profile standard (LaB6 or Si or
similar).
Greetings
Reinhard
Zitat von Habib Boughzala <boughz...@yahoo.com
<mailto:boughz...@yahoo.com>>:
Dear all,
I would like to send you my witness related to this kind of observation.
I can assure that our Bruker D8 is clean and optimized!
In many cases of well conditioned thin film (spin coating or
controlled diffusion) material this kind of phenomenon is
visible around the highest reflection, especially when the
preferred orientation is drastically present.
So, in my opinion, Reinhard and Alan are right, and what is
observed is just like reflections broadening, asymmetry,
shifting ...etc ... and can be related to the material behavior.
Now, what is the physical (crystallographic!) property
responsible of this phenomenon? let's open the floor for a
large discussion.
Habib
------ Message d'origine ------
De "Alan W Hewat" <alan.he...@neutronoptics.com
<mailto:alan.he...@neutronoptics.com>>
À "Reinhard Kleeberg" <kleeb...@mineral.tu-freiberg.de
<mailto:kleeb...@mineral.tu-freiberg.de>>
Cc rietveld_l@ill.fr <mailto:rietveld_l@ill.fr>
Date 04/09/2023 09:29:08
Objet Re: [EXT] Re: [External] Re: Step-like basline
Reinhard is right that it is best to improve the instrument to
produce cleaner data. I'm concerned about the advice to model
all kinds of features whose origin is not fully understood,
simply to obtain a better fit. Shay has told us nothing about
his instrument or his conditions of data collection. He asks
"Is it a sample preparation problem", to which the obvious
reply is "Do you see this with other samples or different
materials" ? Only he can answer that. If the answer is yes, he
might try modifying his instrument (remove filters etc) to see
what effect that has on the pattern from a simple well
characterised material. Again only he can do that. Data
collection is an experimental science, and data refinement
should not be reduced to a "black box" computer program where
extra parameters can be added to reduce the R-factor.
Alan.
On Mon, 4 Sept 2023 at 08:18, Reinhard Kleeberg
<kleeb...@mineral.tu-freiberg.de
<mailto:kleeb...@mineral.tu-freiberg.de>> wrote:
Can be modeled in the BGMN peak profile model as well, by modifying
the *.lam file by a series of additional Lorentzians on the 1/lambda
scale, see figure.
The same can be done for other spectral impurities, e.g. W L
satellites. Also "electronic effects" on the wavelength distribution
profile like the "edges" from the ROI settings of Si drift detectors
can be modelled in such a convolution based approach.
However, better to have a pure/simple wavelength distribution (clear
alpha1/2 doublet) by a monochromator or high energy resolution
detector, as any satellites make trouble in trace phase analysis and
do cause prolonged calculation time in complicated Rietveld
refinements.
Reinhard
Zitat von Matthew Rowles <rowle...@gmail.com
<mailto:rowle...@gmail.com>>:
Topas can model them quite well. The functionality was introduced in
version 5.
On Mon, 4 Sep 2023, 00:54 Kurt Leinenweber, <ku...@asu.edu
<mailto:ku...@asu.edu>> wrote:
Hi, Are these things modeled in Rietveld programs, by
chance? It seems
like a lot of baggage to put in a refinement but if it
makes the results
better…
- Kurt
*From:* rietveld_l-requ...@ill.fr
<mailto:rietveld_l-requ...@ill.fr>
<rietveld_l-requ...@ill.fr
<mailto:rietveld_l-requ...@ill.fr>> *On Behalf
Of *Thomas Gegan
*Sent:* Sunday, September 3, 2023 9:16 AM
*To:* Bish, David L <b...@indiana.edu
<mailto:b...@indiana.edu>>; Shay Tirosh <stiro...@gmail.com
<mailto:stiro...@gmail.com>>;
Fernando Igoa <fer.igoa.1...@gmail.com
<mailto:fer.igoa.1...@gmail.com>>
*Cc:* Rietveld List (rietveld_l@ill.fr
<mailto:rietveld_l@ill.fr>) <rietveld_l@ill.fr
<mailto:rietveld_l@ill.fr>>
*Subject:* RE: [EXT] Re: [External] Re: Step-like basline
I agree with a Ni absorption edge, possibly with a Kβ peak
around 38° 2θ.
*Tom Gegan*
Chemist III
Phone: +1 732 205-5111, Email: tom.ge...@basf.com
<mailto:tom.ge...@basf.com>
Postal Address: BASF Corporation, , 25 Middlesex Essex
Turnpike, 08830
Iselin, United States
*From:* rietveld_l-requ...@ill.fr
<mailto:rietveld_l-requ...@ill.fr>
<rietveld_l-requ...@ill.fr
<mailto:rietveld_l-requ...@ill.fr>> *On Behalf
Of *Bish, David L
*Sent:* Sunday, September 3, 2023 7:08 AM
*To:* Shay Tirosh <stiro...@gmail.com
<mailto:stiro...@gmail.com>>; Fernando Igoa <
fer.igoa.1...@gmail.com <mailto:fer.igoa.1...@gmail.com>>
*Cc:* Rietveld List (rietveld_l@ill.fr
<mailto:rietveld_l@ill.fr>) <rietveld_l@ill.fr
<mailto:rietveld_l@ill.fr>>
*Subject:* [EXT] Re: [External] Re: Step-like basline
Some people who received this message don't often get email from
b...@indiana.edu <mailto:b...@indiana.edu>. Learn why this
is important
<https://urldefense.com/v3/__https:/aka.ms/LearnAboutSenderIdentification__;!!IKRxdwAv5BmarQ!fFhSHn4S5iEzkW-O9lvWG-OzoqK_2SKhRniGa71nxuOL3GcxiyD83i2mnNN0Z48HPkn4zjKqH-aqqA$> Hello
Shay,
I think it is probably related to "tube tails". You can
read about this in
the literature (e.g., on the BGMN web site) and you can
model it in some
Rietveld software such as Topas. You don't normally notice
this but it
becomes apparent with higher-intensity peaks.
Regards,
Dave
------------------------------
*From:* rietveld_l-requ...@ill.fr
<mailto:rietveld_l-requ...@ill.fr>
<rietveld_l-requ...@ill.fr
<mailto:rietveld_l-requ...@ill.fr>> on behalf
of Fernando Igoa <fer.igoa.1...@gmail.com
<mailto:fer.igoa.1...@gmail.com>>
*Sent:* Sunday, September 3, 2023 3:06 AM
*To:* Shay Tirosh <stiro...@gmail.com <mailto:stiro...@gmail.com>>
*Cc:* Rietveld List (rietveld_l@ill.fr
<mailto:rietveld_l@ill.fr>) <rietveld_l@ill.fr
<mailto:rietveld_l@ill.fr>>
*Subject:* [External] Re: Step-like basline
This message was sent from a non-IU address. Please
exercise caution when
clicking links or opening attachments from external sources.
Hey Shay,
Are you using a motorized slit during the measurement?
These may open up
abruptly to compensate for the angular dependence of the
footprint and thus
generate an abrupt increase in the intensity.
Hope it helps :)
On Sun, Sep 3, 2023, 8:50 AM Shay Tirosh
<stiro...@gmail.com <mailto:stiro...@gmail.com>> wrote:
Dear Rietvelders
I am attaching a zoom-in on a diffraction profile.
My question is what is the origin of the step-like profile
next to a very
large reflection peak?
Is it a sample preparation problem?
Is it part of the baseline?
Thanks
Shay
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Formation Rietveld CNRS
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Formation SAXS et Réflectivités pour couches minces et matériaux
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