Re: [EXTERNAL] Re: [EXT] [External] Re: Step-like basline

[Matthew Rowles]

Not only is it a possible explanation, it is the explanation.

It represents the tube bremsstralum truncated by the Ni absorption edge.

As long as you're careful, removing it shouldn't be an issue, although it
is always better to either model it properly, or to not collect such data
on the first place.

Matthew


On Wed, 6 Sep 2023, 16:35 Shay Tirosh,  wrote:

> Dear Reitvelders
>
> I am overwhelmed with your insightful responses. I am grateful for that.
>
> Indeed I have Ni filter and the adsorption added is indeed a good possible
> explanation since we get similar step-like profiles with completely
> different materials and samples.
>
> With the understanding that this step contains no special information that
> I might lose by using Spilne as the baseline subtraction. I just need to
> make sure I am not affecting peak positions and creating artificial peaks
> and humps
>
> Any comments?
>
> Thanks
>
> Shay
>
>
> 
> Virus-free.www.avast.com
> 
> <#m_-4699204290736215942_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>
> On Wed, Sep 6, 2023 at 9:35 AM Reinhard Kleeberg <
> kleeb...@mineral.tu-freiberg.de> wrote:
>
>> Dear Radovan,
>> may be you are right, but this great development will unfortunately
>> not help the big number of lab diffractionists to puzzle the patterns
>> to be analyzed in their daily business ;-)
>> Best regards
>>
>> Reinhard
>>
>> Zitat von Radovan Cerny :
>>
>> > Dear Reinhard,
>> >
>> > I wouldn't say "solely from the detector side". The biggest
>> > improvement is synchrotron radiation (+2D detectors🤓).
>> >
>> > Best greetings from Lac Leman
>> >
>> > Radovan Cerny
>> >
>> > Envoyé à partir de Outlook pour Android
>> > 
>> > From: rietveld_l-requ...@ill.fr  on
>> > behalf of Reinhard Kleeberg 
>> > Sent: Tuesday, September 5, 2023 1:49:57 PM
>> > To: rietveld_l@ill.fr 
>> > Subject: [EXTERNAL] Re: [EXT] [External] Re: Step-like basline
>> >
>> > Dear Luca,
>> > I completely agree and will be very happy to have a 1D detector with
>> > sufficient energy resolution to resolve a "pure" Cu Kalpha1/2 doublet
>> > from W Lalpha1. This would make routine work much easier. IMHO, the
>> > biggest improvements in XRPD instrumentation within the last decades
>> > came solely from the detector side, should be continued.
>> >
>> > Regarding search-match by Rietveld: Your FSPM method is a very
>> > inspiring idea. Nicola Doebelin has incorporated a simplified approach
>> > in PROFEX, too:
>> > https://www.youtube.com/watch?v=Oqj71TiifeI
>> >
>> > I'm routinely applying a run of ~500 structures/minerals what we are
>> > commonly using (+- the former QPA database of Seifert AUTOQUAN or from
>> > the BGMN webpage) for a phase screening of unknown samples, needs ~ 5
>> > min without interaction. Than running QPA refinement with the best
>> > matching structures, clicking on remaining peaks in the difference
>> > plot for getting a proposal of best matching main line positions in
>> > the database, and adding these structure(s) to the refinement, running
>> > again... This is a typical workflow in our lab, no need for peak
>> > search, background treatment, thinking about artifact peaks...
>> >
>> > Best regards
>> >
>> > Reinhard
>> >
>> > Zitat von Luca Lutterotti :
>> >
>> >> Dear Reinhard and Rietvelders,
>> >>
>> >> It is always a compromise. Ideally we would like the fastest
>> >> instrument with a lot of intensity (so, 1D or 2D detectors) but no
>> >> lines outside the Kalpha or even just the Kapha1 like the one of
>> >> James Cline. But this means a monochromator on the incident beam and
>> >> you get fluorescence background. Now I like your solution of the Si
>> >> Drift detector, so you just cut the fluorescence and you don’t need
>> >> the monochromator in the first place.
>> >> So we are working and we are testing some lab prototypes of a 1D Si
>> >> Drift like detector to get the best of both world. It is only a lot
>> >> of electronic, but one day we will have wonderful instrument with
>> >> only the lines we need and no fluorescence for the background.
>> >> Actually we use fluorescence for the chemical analysis (quantitative).
>> >>
>> >> About the search-match problem. Have a look on our FPSM method (
>> >> http://fpsm.radiographema.com/) where we don’t care about extra
>> >> lines as it is a Rietveld search-match. We don’t need to identify or
>> >> search peaks. We don’t use peak positions, we just fit with the
>> >> Rietveld. It is slower indeed, but every day is becoming faster and
>> >> in a few years it will run quickly on our cellphones (I have a
>> >> prototype running there).
>> >>
>> >> Best regards,
>> >>
>> >> Luca
>> >>
>> >>  
>> >>
>> >> Luca Lutterotti
>> >> Dipartimento di Ingegneri

Re: [EXT] [External] Re: Step-like basline

[Luca Lutterotti]

I am glad you find FPSM an inspiring idea, me and my co-workers will be quite 
happy if this will results in some citations. The FPSM publication back in 2019 
was a troubled submission. It took us more than 3 years as initially was just 
rejected (for economical reasons, as it would be unfair against the traditional 
search-match software developed by companies; you read it right, that was the 
reason for rejection by the reviewer and the editor accepted it even if the 
other reviewer was for accepting it as it is). We had some discussion, but no 
way. Then we tried to change journal (www were hesitant as it would have had 
much less visibility on the powder diffraction community) but finally Daniel 
discussed with another editor of the same journal and we re-submitted and got 
some fair reviewers. But it was long and the first rejection a bit shocking. I 
thought before you have to reject for scientific reasons…….

Now I am learning that not only at the academic level, but also some companies 
selling search-match software are including what they call WPF search-match, 
but no one cite the origin of the idea. I hope I don’t get a second 
Loopstra-Rietveld case….. ;-) Well in my case I wrote the software before 
publishing the idea. 
That software was re-written from scratch to optimise for the speed and the 
method. That’s why we can work with several thousand structures at the same 
speed the other softwares work on less than hundreds. I did not use Maud for 
that in fact.

But I want you to know that the last version I developed on a recent EU project 
(not the one online), works also with turbostratic and modulated clay 
structures using your model (the Ufer et al.) to simulate them in the Rietveld. 
It is a fantastic trick that I use for texture analysis but also quantification 
and now in FPSM. Having a quick Rietveld help to search-match samples 
containing clays using data even at high angles (more than 60 degs). I indeed 
don’t pre-calculate and store structures because when you work with many of 
them it takes more time to load all the precalculations from a database (even 
the speedy ones) than to re-calculate everything. 

So I am glad we both made use of each other models/ideas!

Best regards,

Luca

 

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 


> On 5 Sep 2023, at 13:49, Reinhard Kleeberg  
> wrote:
> 
> Dear Luca,
> I completely agree and will be very happy to have a 1D detector with 
> sufficient energy resolution to resolve a "pure" Cu Kalpha1/2 doublet from W 
> Lalpha1. This would make routine work much easier. IMHO, the biggest 
> improvements in XRPD instrumentation within the last decades came solely from 
> the detector side, should be continued.
> 
> Regarding search-match by Rietveld: Your FSPM method is a very inspiring 
> idea. Nicola Doebelin has incorporated a simplified approach in PROFEX, too:
> https://www.youtube.com/watch?v=Oqj71TiifeI
> 
> I'm routinely applying a run of ~500 structures/minerals what we are commonly 
> using (+- the former QPA database of Seifert AUTOQUAN or from the BGMN 
> webpage) for a phase screening of unknown samples, needs ~ 5 min without 
> interaction. Than running QPA refinement with the best matching structures, 
> clicking on remaining peaks in the difference plot for getting a proposal of 
> best matching main line positions in the database, and adding these 
> structure(s) to the refinement, running again... This is a typical workflow 
> in our lab, no need for peak search, background treatment, thinking about 
> artifact peaks...
> 
> Best regards
> 
> Reinhard
> 
> Zitat von Luca Lutterotti  >:
> 
>> Dear Reinhard and Rietvelders,
>> 
>> It is always a compromise. Ideally we would like the fastest instrument with 
>> a lot of intensity (so, 1D or 2D detectors) but no lines outside the Kalpha 
>> or even just the Kapha1 like the one of James Cline. But this means a 
>> monochromator on the incident beam and you get fluorescence background. Now 
>> I like your solution of the Si Drift detector, so you just cut the 
>> fluorescence and you don’t need the monochromator in the first place.
>> So we are working and we are testing some lab prototypes of a 1D Si Drift 
>> like detector to get the best of both world. It is only a lot of electronic, 
>> but one day we will have wonderful instrument with only the lines we need 
>> and no fluorescence for the background. Actually we use fluorescence for the 
>> chemical analysis (quantitative).
>> 
>> About the search-match problem. Have a look on our FPSM method (
>> http://fpsm.radiographema.com/) where we don’t care about extra lines as it 
>> is a Rietveld search-match. We don’t need to identify or search peaks. We 
>> don’t use peak posit

Re: Step-like basline

[Luca Lutterotti]

It is call graininess, as Miguel said before, these are mosaic single crystals 
and depending on your source (divergence, spot dimension at different angles 
etc.) you get each mosaic crystal to create a diffraction peak that especially 
at low two-theta angle may be displaced a lot from its theoretical position 
because it is diffracting from a non center position. This is what you get also 
when you analyse samples with extremely large grains. If you use a 2D detector 
instead of scanning with a point or small psd, you will see all these 
individual grain or mosaic crystals diffracting around their ideal spot or if 
it is a sample with just large grains, distributed around the Laue circle. More 
the grain is on a lateral position respect to the center of the beam, more it 
is displaced in two-theta. At higher angle your beam size on the sample is 
smaller and there is less displacement for geometrical reasons.
I like to work with 2D detectors (texture, stresses) because it is easy to see 
these “figures”.
In addition you have the spectral impurities identified by Frank and you may 
get some small grains with different orientation and twins that will create 
some of the non 00l peaks.
Analysing these kind of patterns would require a sophisticated simulation of 
the grains-crystals distribution and computing like ray-tracing for the 
geometrical effects. Not worth it. Single crystals and sharp textures requires 
a point beam to avoid these effects. And a monochromatic one.

Best regards,

Luca

 

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 


> On 6 Sep 2023, at 17:43, Le Bail Armel  wrote:
> 
> Dear Frank,
> 
> Same as you. I have not a complete solution.
> 
> Best
> 
> Armel
> 
>> envoyé : 6 septembre 2023 à 16:57
>> de : Frank Girgsdies > >
>> à : Le Bail Armel mailto:le-bail.ar...@orange.fr>>
>> Cc: Rietveld_L mailto:Rietveld_L@ill.fr>>
>> objet : Re: Step-like basline
>> 
>> 
>> Dear Armel,
>> 
>> Thanks for this nice quiz!
>> 
>> However, after identifying the following spectral impurities:
>> Cu K_beta,
>> W L_alpha1,2
>> W L_beta1,2,3,4 and
>> W L_gamma1,
>> I am stuck now, leaving bout 1/2 to 1/3 of the tiny extra peaks 
>> unexplained.
>> 
>> Some of them look suspiciously like Cu K_alpha1+2 doublets and might 
>> thus belong to an impurity phase, or differently oriented crystallites 
>> of the main phase, which could lie as dust on the single crystal 
>> surface, but I had no luck trying to identify them.
>> 
>> Furthermore, the irregular high angle tailing of the 00l series (maybe 
>> stacking faults?) makes peak fitting difficult.
>> 
>> Thus, I give up (at least for now), hoping that you might disclose the 
>> solution to the riddle, as far as it is known, for us after a while.
>> 
>> Best wishes,
>> Frank
>> 
>> 
>> 
>> On 06.09.2023 10:47, Le Bail Armel wrote:
>> 
>>> Hi,
>>> 
>>> In the same subject.
>>> 
>>> A special "powder pattern" to play with (try to explain all peaks) :
>>> 
>>> http://cristal.org/muscovite.pdf 
>>> 
>>> Best
>>> 
>>> Armel
>>> 
>>> 
>>> ++
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>>> Send commands to  eg: HELP as the subject with no body text
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>>> ++
>>> 
>> >
>> 
> ++
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> ++

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Re: Step-like basline

[Le Bail Armel]

Dear Frank,Same as you. I have not a complete solution.BestArmelenvoyé : 6 septembre 2023 à 16:57de : Frank Girgsdies à : Le Bail Armel Cc: Rietveld_L objet : Re: Step-like baslineDear Armel,Thanks for this nice quiz!However, after identifying the following spectral impurities: Cu K_beta, W L_alpha1,2 W L_beta1,2,3,4 and W L_gamma1,I am stuck now, leaving bout 1/2 to 1/3 of the tiny extra peaks unexplained.Some of them look suspiciously like Cu K_alpha1+2 doublets and might thus belong to an impurity phase, or differently oriented crystallites of the main phase, which could lie as dust on the single crystal surface, but I had no luck trying to identify them.Furthermore, the irregular high angle tailing of the 00l series (maybe stacking faults?) makes peak fitting difficult.Thus, I give up (at least for now), hoping that you might disclose the solution to the riddle, as far as it is known, for us after a while.Best wishes,FrankOn 06.09.2023 10:47, Le Bail Armel wrote:Hi,In the same subject.A special "powder pattern" to play with (try to explain all peaks) :http://cristal.org/muscovite.pdf BestArmel++Please do NOT attach files to the whole list Send commands to  eg: HELP as the subject with no body textThe Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/++>
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Re: Step-like basline

[Frank Girgsdies]

Dear Armel,

Thanks for this nice quiz!

However, after identifying the following spectral impurities:
 Cu K_beta,
 W L_alpha1,2
 W L_beta1,2,3,4 and
 W L_gamma1,
I am stuck now, leaving bout 1/2 to 1/3 of the tiny extra peaks 
unexplained.


Some of them look suspiciously like Cu K_alpha1+2 doublets and might 
thus belong to an impurity phase, or differently oriented crystallites 
of the main phase, which could lie as dust on the single crystal 
surface, but I had no luck trying to identify them.


Furthermore, the irregular high angle tailing of the 00l series (maybe 
stacking faults?) makes peak fitting difficult.


Thus, I give up (at least for now), hoping that you might disclose the 
solution to the riddle, as far as it is known, for us after a while.


Best wishes,
Frank



On 06.09.2023 10:47, Le Bail Armel wrote:

Hi,

In the same subject.

A special "powder pattern" to play with (try to explain all peaks) :

http://cristal.org/muscovite.pdf 

Best

Armel


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Re: HiCANS (Hight Current Accelerator-driven Neutron Source)

[Yaroslav Filinchuk]

Hi Alan,

Accelerator-driven neutron sources are a lot cheaper than spallation 
sources. Moreover, Figure 54 in the ICONE document shows that the 
scientific productivity of neutron sources does not depend on the flux 
of the source. And the biggest point might be the return to building new 
neutron facilities.


Thank you, Armel, for sharing this document!

Best regards,

Yaroslav


On 06.09.2023 14:37, Alan W Hewat wrote:
Glad you are following neutron developments Armel. This document 
points out how French science has suffered due to the shutdown of the 
only national neutron sources, in Grenoble and Paris. It argues that 
ESS when it is finally operational, cannot possibly satisfy the 
national requirement if ILL is also shut down. Hopefully that won't 
happen any time soon, given the apparent renaissance of interest in 
nuclear due to the current energy crisis, and the neglect of science 
by governments for most of my 50 year life in France. It is however 
slightly worrying that instrument performance on a possible HICANS 
accelerator source is projected to be inferior to instruments on 
Orphée. That seems too pessimistic given the performance of ISIS in 
the UK.


But perhaps you were trying to use this document to make some other 
point :-) ?


Alan

Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://neutronoptics.com/hewat 


___

On Wed, 6 Sept 2023, 13:31 Le Bail Armel,  wrote:

Interesting document about neutrons in French, though the word
"Rietveld"

appears only once, page 162, the word "poudre" (=powder) is more
frequent :

https://2fdn.cnrs.fr/wp-content/uploads/2023/09/ICONE-digital.pdf


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Re: HiCANS (Hight Current Accelerator-driven Neutron Source)

[Alan W Hewat]

Glad you are following neutron developments Armel. This document points out
how French science has suffered due to the shutdown of the only national
neutron sources, in Grenoble and Paris. It argues that ESS when it is
finally operational, cannot possibly satisfy the national requirement if
ILL is also shut down. Hopefully that won't happen any time soon, given the
apparent renaissance of interest in nuclear due to the current energy
crisis, and the neglect of science by governments for most of my 50 year
life in France. It is however slightly worrying that instrument performance
on a possible HICANS accelerator source is projected to be inferior to
instruments on Orphée. That seems too pessimistic given the performance of
ISIS in the UK.

But perhaps you were trying to use this document to make some other point
:-) ?

Alan

Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Wed, 6 Sept 2023, 13:31 Le Bail Armel,  wrote:

> Interesting document about neutrons in French, though the word "Rietveld"
>
> appears only once, page 162, the word "poudre" (=powder) is more frequent :
>
> https://2fdn.cnrs.fr/wp-content/uploads/2023/09/ICONE-digital.pdf
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
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HiCANS (Hight Current Accelerator-driven Neutron Source)

[Le Bail Armel]

Interesting document about neutrons in French, though the word "Rietveld"appears only once, page 162, the word "poudre" (=powder) is more frequent :https://2fdn.cnrs.fr/wp-content/uploads/2023/09/ICONE-digital.pdf
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Re: [EXTERNAL] Re: Step-like basline

[Alan W Hewat]

You are right Radovan. The sample mail-in system is one way of improving SR
and N access times. "Discretionary time" reserved for people who have a hot
experiment and can come at short notice, is another, together with speeding
up the usual proposal system. These mechanisms already apply at ILL, but
on-site manpower is a limiting factor. And yes, a SR pattern will almost
always be superior to a lab pattern, because you can afford an instrument
to produce a cleaner pattern, and it is also easier with a monochromated
white beam.

Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Wed, 6 Sept 2023, 11:31 Radovan Cerny,  wrote:

> No, you are not provocative Alan. You are right. I have reacted only to
> the X-ray discussion (no neutrons in the labs).
> It is a pity that the procedure for getting the beamtime at the
> synchrotron and neutron sources is still so time-consuming. At least at the
> synchrotron, there is an activity to introduce or improve already existing
> mail-in system. I have a feeling that there is enough synchrotron beamtime
> for everybody to collect standard powder patterns. 20-60 sec / pattern with
> 2D detector + few min. for sample mounting is not so much.
> Who has analyzed powder patterns from synchrotron will never come back to
> the lab (this is provocative 🙂)
>
> Radovan
>
>
> Radovan Cerny
> DQMP
> Université de Genève
> 24, quai Ernest-Ansermet
> CH-1211 Geneva 4, Switzerland
> mailto : radovan.ce...@unige.ch
> URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm
> --
> *De :* rietveld_l-requ...@ill.fr  de la part
> de Alan W Hewat 
> *Envoyé :* mercredi 6 septembre 2023 11:17
> *À :* Le Bail Armel 
> *Cc :* Rietveld_L 
> *Objet :* [EXTERNAL] Re: Step-like basline
>
> "*The biggest improvement was synchrotron radiation*".
> No. The biggest improvement for the profile refinement of atomic and
> magnetic structures (Rietveld refinement in the strict sense) was high
> resolution neutron powder diffractometers with large area detectors :-)
> Even SR gives undue weight to heavy atoms, can suffer from systematic
> errors due to small samples, and of course is "not ideal" for magnetism,
> important for the properties of many materials. SR has some advantages to
> counter these disadvantages, but not for most new materials. Lab x-rays can
> do some structural work, but have most application for materials
> characterisation by multi-component profile refinement, when you need a
> result now, and not in 6 months time.
>
> But Radovan, is just being provocative (like me).
>
> Alan
>
>
> 
> Dr Alan Hewat, NeutronOptics
> Grenoble, FRANCE (from phone)
> alan.he...@neutronoptics.com
> +33.476984168 VAT:FR79499450856
> http://NeutronOptics.com/hewat
> ___
>
>
> On Wed, 6 Sept 2023, 10:48 Le Bail Armel,  wrote:
>
> Hi,
>
> In the same subject.
>
> A special "powder pattern" to play with (try to explain all peaks) :
>
> http://cristal.org/muscovite.pdf
>
> Best
>
> Armel
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
++
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RE: [EXTERNAL] Re: Step-like basline

[Radovan Cerny]

No, you are not provocative Alan. You are right. I have reacted only to the 
X-ray discussion (no neutrons in the labs).
It is a pity that the procedure for getting the beamtime at the synchrotron and 
neutron sources is still so time-consuming. At least at the synchrotron, there 
is an activity to introduce or improve already existing mail-in system. I have 
a feeling that there is enough synchrotron beamtime for everybody to collect 
standard powder patterns. 20-60 sec / pattern with 2D detector + few min. for 
sample mounting is not so much.
Who has analyzed powder patterns from synchrotron will never come back to the 
lab (this is provocative 🙂)

Radovan


Radovan Cerny
DQMP
Université de Genève
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
mailto : radovan.ce...@unige.ch
URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm

De : rietveld_l-requ...@ill.fr  de la part de Alan W 
Hewat 
Envoyé : mercredi 6 septembre 2023 11:17
À : Le Bail Armel 
Cc : Rietveld_L 
Objet : [EXTERNAL] Re: Step-like basline

"The biggest improvement was synchrotron radiation".
No. The biggest improvement for the profile refinement of atomic and magnetic 
structures (Rietveld refinement in the strict sense) was high resolution 
neutron powder diffractometers with large area detectors :-) Even SR gives 
undue weight to heavy atoms, can suffer from systematic errors due to small 
samples, and of course is "not ideal" for magnetism, important for the 
properties of many materials. SR has some advantages to counter these 
disadvantages, but not for most new materials. Lab x-rays can do some 
structural work, but have most application for materials characterisation by 
multi-component profile refinement, when you need a result now, and not in 6 
months time.

But Radovan, is just being provocative (like me).

Alan



Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Wed, 6 Sept 2023, 10:48 Le Bail Armel, 
mailto:le-bail.ar...@orange.fr>> wrote:

Hi,

In the same subject.

A special "powder pattern" to play with (try to explain all peaks) :

http://cristal.org/muscovite.pdf

Best

Armel

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Re: Step-like basline

[miguel gregorkiewitz]

Nice example for real world, Armel!

These huge flakes are by no means single crystals, so I tend to interpret
the small peaks in the feet of the maxima as stemming from slightly
misaligned regions, sort of graininess.

Did you try under the polarizing microscope?

Best

Miguel


El mié, 6 sep. 2023 10:48, Le Bail Armel  escribió:

> Hi,
>
> In the same subject.
>
> A special "powder pattern" to play with (try to explain all peaks) :
>
> http://cristal.org/muscovite.pdf
>
> Best
>
> Armel
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
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Re: Step-like basline

[Alan W Hewat]

"*The biggest improvement was synchrotron radiation*".
No. The biggest improvement for the profile refinement of atomic and
magnetic structures (Rietveld refinement in the strict sense) was high
resolution neutron powder diffractometers with large area detectors :-)
Even SR gives undue weight to heavy atoms, can suffer from systematic
errors due to small samples, and of course is "not ideal" for magnetism,
important for the properties of many materials. SR has some advantages to
counter these disadvantages, but not for most new materials. Lab x-rays can
do some structural work, but have most application for materials
characterisation by multi-component profile refinement, when you need a
result now, and not in 6 months time.

But Radovan, is just being provocative (like me).

Alan



Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Wed, 6 Sept 2023, 10:48 Le Bail Armel,  wrote:

> Hi,
>
> In the same subject.
>
> A special "powder pattern" to play with (try to explain all peaks) :
>
> http://cristal.org/muscovite.pdf
>
> Best
>
> Armel
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  eg: HELP as the subject with no body
> text
> The Rietveld_L list archive is on
> http://www.mail-archive.com/rietveld_l@ill.fr/
> ++
>
>
++
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++

Re: Step-like basline

[Le Bail Armel]

Hi,In the same subject.A special "powder pattern" to play with (try to explain all peaks) :http://cristal.org/muscovite.pdfBestArmel
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++

Re: [EXTERNAL] Re: [EXT] [External] Re: Step-like basline

[Shay Tirosh]

Dear Reitvelders

I am overwhelmed with your insightful responses. I am grateful for that.

Indeed I have Ni filter and the adsorption added is indeed a good possible
explanation since we get similar step-like profiles with completely
different materials and samples.

With the understanding that this step contains no special information that
I might lose by using Spilne as the baseline subtraction. I just need to
make sure I am not affecting peak positions and creating artificial peaks
and humps

Any comments?

Thanks

Shay


Virus-free.www.avast.com

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Wed, Sep 6, 2023 at 9:35 AM Reinhard Kleeberg <
kleeb...@mineral.tu-freiberg.de> wrote:

> Dear Radovan,
> may be you are right, but this great development will unfortunately
> not help the big number of lab diffractionists to puzzle the patterns
> to be analyzed in their daily business ;-)
> Best regards
>
> Reinhard
>
> Zitat von Radovan Cerny :
>
> > Dear Reinhard,
> >
> > I wouldn't say "solely from the detector side". The biggest
> > improvement is synchrotron radiation (+2D detectors🤓).
> >
> > Best greetings from Lac Leman
> >
> > Radovan Cerny
> >
> > Envoyé à partir de Outlook pour Android
> > 
> > From: rietveld_l-requ...@ill.fr  on
> > behalf of Reinhard Kleeberg 
> > Sent: Tuesday, September 5, 2023 1:49:57 PM
> > To: rietveld_l@ill.fr 
> > Subject: [EXTERNAL] Re: [EXT] [External] Re: Step-like basline
> >
> > Dear Luca,
> > I completely agree and will be very happy to have a 1D detector with
> > sufficient energy resolution to resolve a "pure" Cu Kalpha1/2 doublet
> > from W Lalpha1. This would make routine work much easier. IMHO, the
> > biggest improvements in XRPD instrumentation within the last decades
> > came solely from the detector side, should be continued.
> >
> > Regarding search-match by Rietveld: Your FSPM method is a very
> > inspiring idea. Nicola Doebelin has incorporated a simplified approach
> > in PROFEX, too:
> > https://www.youtube.com/watch?v=Oqj71TiifeI
> >
> > I'm routinely applying a run of ~500 structures/minerals what we are
> > commonly using (+- the former QPA database of Seifert AUTOQUAN or from
> > the BGMN webpage) for a phase screening of unknown samples, needs ~ 5
> > min without interaction. Than running QPA refinement with the best
> > matching structures, clicking on remaining peaks in the difference
> > plot for getting a proposal of best matching main line positions in
> > the database, and adding these structure(s) to the refinement, running
> > again... This is a typical workflow in our lab, no need for peak
> > search, background treatment, thinking about artifact peaks...
> >
> > Best regards
> >
> > Reinhard
> >
> > Zitat von Luca Lutterotti :
> >
> >> Dear Reinhard and Rietvelders,
> >>
> >> It is always a compromise. Ideally we would like the fastest
> >> instrument with a lot of intensity (so, 1D or 2D detectors) but no
> >> lines outside the Kalpha or even just the Kapha1 like the one of
> >> James Cline. But this means a monochromator on the incident beam and
> >> you get fluorescence background. Now I like your solution of the Si
> >> Drift detector, so you just cut the fluorescence and you don’t need
> >> the monochromator in the first place.
> >> So we are working and we are testing some lab prototypes of a 1D Si
> >> Drift like detector to get the best of both world. It is only a lot
> >> of electronic, but one day we will have wonderful instrument with
> >> only the lines we need and no fluorescence for the background.
> >> Actually we use fluorescence for the chemical analysis (quantitative).
> >>
> >> About the search-match problem. Have a look on our FPSM method (
> >> http://fpsm.radiographema.com/) where we don’t care about extra
> >> lines as it is a Rietveld search-match. We don’t need to identify or
> >> search peaks. We don’t use peak positions, we just fit with the
> >> Rietveld. It is slower indeed, but every day is becoming faster and
> >> in a few years it will run quickly on our cellphones (I have a
> >> prototype running there).
> >>
> >> Best regards,
> >>
> >> Luca
> >>
> >>  
> >>
> >> 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 
> >>
> >>
> >>> Begin forwarded message:
> >>>
> >>> From: Reinhard Kleeberg 
> >>> Subject: Re: [EXT] [External] Re: Step-like basline
> >>> Date: 5 September 2023 at 08:56:15 CEST
> >>> To: rietveld_l@ill.fr
> >>> Reply-To: Reinhard Kleeberg 
> >>>
> >>> Dear Luca,
> >>> I completely