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>
À "Habib Boughzala" <boughz...@yahoo.com>
Cc 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>:
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>
À "Reinhard Kleeberg" <kleeb...@mineral.tu-freiberg.de>
Cc 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> 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>:
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> 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 <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>; Shay Tirosh <stiro...@gmail.com>;
Fernando Igoa <fer.igoa.1...@gmail.com>
*Cc:* Rietveld List (rietveld_l@ill.fr) <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
Postal Address: BASF Corporation, , 25 Middlesex Essex Turnpike, 08830
Iselin, United States
*From:* rietveld_l-requ...@ill.fr <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>; Fernando Igoa <
fer.igoa.1...@gmail.com>
*Cc:* Rietveld List (rietveld_l@ill.fr) <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. Learn why this is important
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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 <rietveld_l-requ...@ill.fr> on behalf
of Fernando Igoa <fer.igoa.1...@gmail.com>
*Sent:* Sunday, September 3, 2023 3:06 AM
*To:* Shay Tirosh <stiro...@gmail.com>
*Cc:* Rietveld List (rietveld_l@ill.fr) <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> 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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-- TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
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Tel. ++49 (0) 3731-39-3244
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