Re: 2-theta shift due to sample displacement in parallel beam

2017-02-02 Thread Toby, Brian H. 
Shay,

I have to disagree with much of the previous discussion. Yes, there are 
aberrations in two-theta with sample displacement in a pseudo-parallel beam 
instrument and they are different for displacement along the beam direction and 
for displacement perpendicular to the beam (but in the detection plane). 
Typically you can only see the first correction when data are collected over a 
very wide angular range (>150 degrees) so this is almost never noticed with 
x-rays. The functional form for the corrections is coded into GSAS-II, so if 
you want read through the source code you can see what they are or you can do 
some simulations to see the effect. The functional form for these corrections 
are completely different from those for Bragg-Brentato geometry, which is 
extremely sensitive to the sample height and in some cases sample transparency.

   The Debye-Sherrer geometry corrections are typically very minor. When only 
the second term is needed, the correction can be replaced with small shifts in 
the two-theta zero correction and lattice constants. This is why in practice 
with synchrotrons and CW neutrons one does not see the problems with sample 
placement that leads to large peak shifts in a Bragg-Brentano geometry, making 
it much easier to index patterns from synchrotron data, but it is not true that 
there are no corrections.

Brian


On Feb 2, 2017, at 9:14 AM, Shay Tirosh 
mailto:stiro...@gmail.com>> wrote:

Dear Rietvelders

Does the 2-teta shift due to sample displacement in parallel beam is similar to 
Bragg Brentano mode?
If not then what is the mathematical expression in parallel beam?

Thanks

Shay
--
_

Dr. Shay Tirosh
Institute for Nanotechnology & Advanced Materials
Bar Ilan University
Ramat Gan, 52900
Israel
Phone: +972-(0)30-531-7320
Mobile: +972-(0)54-8834533
Email: stiro...@gmail.com
_
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Re: 2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Matthew Rowles 
J. Appl. Cryst.  (2003). *36*
, 926-930
https://doi.org/10.1107/S0021889803006757
Use of double GoÈbel mirrors with high-temperature stages for powder
diffraction: a strategy to avoid severe intensity fade
Pamela S. Whitfield

.

and I meant "The only effect that.." I can only blame insomnia and
autocorrect for that faux pas.


On 3 February 2017 at 03:01, Whitfield, Pamela S. 
wrote:

> Many, many, many years ago in a galaxy far away I wrote a paper that
> probably no-one read that had some systematic data on this for a double
> mirror parallel beam system (second mirror as an ‘analyzer’) in flat-plate
> theta-theta geometry. This setup is much more sensitive to displacement
> than most but readily shows the effect on position and intensity.
>
> Hunt around in J.Appl.Cryst. for 2003 and you should be able to find it
> buried under a pile of more interesting papers… ;-)
>
>
>
> Pam
>
>
>
> Dr Pamela Whitfield MRSC CChem
>
> Instrument Scientist – POWGEN
>
> Spallation Neutron Source
>
> Oak Ridge National Laboratory
>
> PO Box 2008, MS-6475
>
> Oak Ridge, TN 37831-6475
>
>  Tel: (865) 235-2605
>
> Fax: (865) 574-6080
>
>
>
> Chair: IUCr Commission on Powder Diffraction
>
>
>
> *From:* rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] *On
> Behalf Of *Nicolich, Jeffrey
> *Sent:* Thursday, February 02, 2017 1:36 PM
> *To:* Shay Tirosh
> *Cc:* rietveld_l@ill.fr
> *Subject:* RE: 2-teta shift due to sample displacement in parallel beam
>
>
>
> Shay,
>
>
>
> The important part is to have a parallel beam analyzer (crystal, parallel
> plate collimator or equivalent). The analyzer will then define the 2-theta
> position, not the sample.
>
>
>
> A more interesting question is regarding the intensities. Sample
> displacement will affect intensities in parallel beam geometry. The
> relationship depends on many factors, e.g. fixed or symmetric incident
> angle, surface roughness, sample transparency, flat plate or capillary, …
>
>
>
>
>
> Jeff
>
>
>
> Jeffrey Nicolich, Ph.D. | Principal Scientist
>
> *GCP Applied Technologies*
>
> 62 Whittemore Avenue | Cambridge, MA 02140 | T +1 617.498.3816
> <(617)%20498-3816> | jeffrey.nicol...@gcpat.com
> 
>
>
> THIS E-MAIL AND ANY ATTACHED FILES ARE CONFIDENTIAL AND MAY BE LEGALLY
> PRIVILEGED. If you are not the addressee, any disclosure, reproduction,
> copying, distribution, or use of this communication is strictly prohibited.
> If you have received this transmission in error please notify the sender
> immediately and then delete this e-mail.
>
>
>
>
>
>
>
>
>
> *From:* rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr
> ] *On Behalf Of *Martin Vickers
> *Sent:* Thursday, February 02, 2017 1:21 PM
> *To:* Shay Tirosh
> *Cc:* rietveld_l@ill.fr
> *Subject:* Re: 2-teta shift due to sample displacement in parallel beam
>
>
>
> Hi, Shay. The sample displacement / peak-position relationship is
> equivalent.
>
>
>
> Martin
>
>
>
> On 2 February 2017 at 15:14, Shay Tirosh  wrote:
>
> Dear Rietvelders
>
>
>
> Does the 2-teta shift due to sample displacement in parallel beam is
> similar to Bragg Brentano mode?
>
> If not then what is the mathematical expression in parallel beam?
>
>
>
> Thanks
>
>
>
> Shay
> --
>
> _
>
>
>
> Dr. Shay Tirosh
>
> Institute for Nanotechnology & Advanced Materials
>
> Bar Ilan University
>
> Ramat Gan, 52900
>
> Israel
> Phone: +972-(0)30-531-7320
>
> Mobile: +972-(0)54-8834533 <+972%2054-883-4533>
>
> Email: stiro...@gmail.com
>
> _
>
>
> ++
> 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/
> ++
>
>
>
>
>
> --
>
> Martin Vickers
> Dept. of Chemistry, UCL,
> 20, Gordon Street
> WC1H 0AJ
> 020 7679 5592 (or ex 25592)
>
> ++
> 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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NHMLA Collections Study Award for Students

2017-02-02 Thread Aaron Celestian 
Dear Colleagues,

I would like to inform you of the new "NHMLA Student Collections Study
Awards" program at the Natural History Museum of Los Angeles County. These
awards provide financial assistance for undergraduate and graduate students
to study the scientific collections housed in the NHM Family of Museums.
The upcoming application deadline is April 1st, 2017, and complete details
of the award and application can be found here:
http://www.nhm.org/site/research-collections/grants. I would greatly
appreciate your help in spreading the word to any eligible students that
might be interested in this opportunity.

Feel free to email me if you have any questions.

Aaron

- - - -
Aaron J. Celestian, Ph.D.
Associate Curator, Mineral Sciences
Natural History Museum of Los Angeles County
http://www.nhm.org/site/research-collections/mineral-sciences
https://www.researchgate.net/profile/Aaron_Celestian
Office: (213) 763-3360 
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RE: 2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Matthew Rowles 
The only affect that specimen displacement should have on intensities with
a parallel beam is a diminution sure to the diffracted beam being so far
away that the parallel plate collimator cuts of the beam.

If you don't have any diffracted beam optics, then that won't be an issue,
but then you will have a specimen displacement correction. The exact form
depends on the geometry.

If you are running in fixed incident beam mode, or transmission, then
you'll have other intensity, absorption, and displacement corrections to
worry about.

Have a look at
MR Rowles, IC Madsen
Journal of Applied Crystallography 43 (3), 632-634, 2010
And
Rowles & Buckley. J. Appl. Cryst. (2017). *50
*, 240-251

https://doi.org/10.1107/S160057671785

Matthew


On 3 Feb 2017 02:38, "Nicolich, Jeffrey"  wrote:

Shay,



The important part is to have a parallel beam analyzer (crystal, parallel
plate collimator or equivalent). The analyzer will then define the 2-theta
position, not the sample.



A more interesting question is regarding the intensities. Sample
displacement will affect intensities in parallel beam geometry. The
relationship depends on many factors, e.g. fixed or symmetric incident
angle, surface roughness, sample transparency, flat plate or capillary, …





Jeff



Jeffrey Nicolich, Ph.D. | Principal Scientist

*GCP Applied Technologies*

62 Whittemore Avenue | Cambridge, MA 02140 | T +1 617.498.3816
<(617)%20498-3816> | jeffrey.nicol...@gcpat.com 


THIS E-MAIL AND ANY ATTACHED FILES ARE CONFIDENTIAL AND MAY BE LEGALLY
PRIVILEGED. If you are not the addressee, any disclosure, reproduction,
copying, distribution, or use of this communication is strictly prohibited.
If you have received this transmission in error please notify the sender
immediately and then delete this e-mail.









*From:* rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] *On
Behalf Of *Martin Vickers
*Sent:* Thursday, February 02, 2017 1:21 PM
*To:* Shay Tirosh
*Cc:* rietveld_l@ill.fr
*Subject:* Re: 2-teta shift due to sample displacement in parallel beam



Hi, Shay. The sample displacement / peak-position relationship is
equivalent.



Martin



On 2 February 2017 at 15:14, Shay Tirosh  wrote:

Dear Rietvelders



Does the 2-teta shift due to sample displacement in parallel beam is
similar to Bragg Brentano mode?

If not then what is the mathematical expression in parallel beam?



Thanks



Shay
-- 

_



Dr. Shay Tirosh

Institute for Nanotechnology & Advanced Materials

Bar Ilan University

Ramat Gan, 52900

Israel
Phone: +972-(0)30-531-7320

Mobile: +972-(0)54-8834533 <+972%2054-883-4533>

Email: stiro...@gmail.com

_


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-- 

Martin Vickers
Dept. of Chemistry, UCL,
20, Gordon Street
WC1H 0AJ
020 7679 5592 (or ex 25592)

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RE: 2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Whitfield, Pamela S. 
Many, many, many years ago in a galaxy far away I wrote a paper that probably 
no-one read that had some systematic data on this for a double mirror parallel 
beam system (second mirror as an ‘analyzer’) in flat-plate theta-theta 
geometry. This setup is much more sensitive to displacement than most but 
readily shows the effect on position and intensity.
Hunt around in J.Appl.Cryst. for 2003 and you should be able to find it buried 
under a pile of more interesting papers… ;-)

Pam

Dr Pamela Whitfield MRSC CChem
Instrument Scientist – POWGEN
Spallation Neutron Source
Oak Ridge National Laboratory
PO Box 2008, MS-6475
Oak Ridge, TN 37831-6475
 Tel: (865) 235-2605
Fax: (865) 574-6080

Chair: IUCr Commission on Powder Diffraction

From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of 
Nicolich, Jeffrey
Sent: Thursday, February 02, 2017 1:36 PM
To: Shay Tirosh
Cc: rietveld_l@ill.fr
Subject: RE: 2-teta shift due to sample displacement in parallel beam

Shay,

The important part is to have a parallel beam analyzer (crystal, parallel plate 
collimator or equivalent). The analyzer will then define the 2-theta position, 
not the sample.

A more interesting question is regarding the intensities. Sample displacement 
will affect intensities in parallel beam geometry. The relationship depends on 
many factors, e.g. fixed or symmetric incident angle, surface roughness, sample 
transparency, flat plate or capillary, …


Jeff

Jeffrey Nicolich, Ph.D. | Principal Scientist
GCP Applied Technologies
62 Whittemore Avenue | Cambridge, MA 02140 | T +1 617.498.3816 | 
jeffrey.nicol...@gcpat.com

THIS E-MAIL AND ANY ATTACHED FILES ARE CONFIDENTIAL AND MAY BE LEGALLY 
PRIVILEGED. If you are not the addressee, any disclosure, reproduction, 
copying, distribution, or use of this communication is strictly prohibited. If 
you have received this transmission in error please notify the sender 
immediately and then delete this e-mail.




From: rietveld_l-requ...@ill.fr 
[mailto:rietveld_l-requ...@ill.fr] On Behalf Of Martin Vickers
Sent: Thursday, February 02, 2017 1:21 PM
To: Shay Tirosh
Cc: rietveld_l@ill.fr
Subject: Re: 2-teta shift due to sample displacement in parallel beam

Hi, Shay. The sample displacement / peak-position relationship is equivalent.

Martin

On 2 February 2017 at 15:14, Shay Tirosh 
mailto:stiro...@gmail.com>> wrote:
Dear Rietvelders

Does the 2-teta shift due to sample displacement in parallel beam is similar to 
Bragg Brentano mode?
If not then what is the mathematical expression in parallel beam?

Thanks

Shay
--
_

Dr. Shay Tirosh
Institute for Nanotechnology & Advanced Materials
Bar Ilan University
Ramat Gan, 52900
Israel
Phone: +972-(0)30-531-7320
Mobile: +972-(0)54-8834533
Email: stiro...@gmail.com
_

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--
Martin Vickers
Dept. of Chemistry, UCL,
20, Gordon Street
WC1H 0AJ
020 7679 5592 (or ex 25592)
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RE: 2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Nicolich, Jeffrey 
Shay,

The important part is to have a parallel beam analyzer (crystal, parallel plate 
collimator or equivalent). The analyzer will then define the 2-theta position, 
not the sample.

A more interesting question is regarding the intensities. Sample displacement 
will affect intensities in parallel beam geometry. The relationship depends on 
many factors, e.g. fixed or symmetric incident angle, surface roughness, sample 
transparency, flat plate or capillary, …


Jeff

Jeffrey Nicolich, Ph.D. | Principal Scientist
GCP Applied Technologies
62 Whittemore Avenue | Cambridge, MA 02140 | T +1 617.498.3816 | 
jeffrey.nicol...@gcpat.com

THIS E-MAIL AND ANY ATTACHED FILES ARE CONFIDENTIAL AND MAY BE LEGALLY 
PRIVILEGED. If you are not the addressee, any disclosure, reproduction, 
copying, distribution, or use of this communication is strictly prohibited. If 
you have received this transmission in error please notify the sender 
immediately and then delete this e-mail.




From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of 
Martin Vickers
Sent: Thursday, February 02, 2017 1:21 PM
To: Shay Tirosh
Cc: rietveld_l@ill.fr
Subject: Re: 2-teta shift due to sample displacement in parallel beam

Hi, Shay. The sample displacement / peak-position relationship is equivalent.

Martin

On 2 February 2017 at 15:14, Shay Tirosh 
mailto:stiro...@gmail.com>> wrote:
Dear Rietvelders

Does the 2-teta shift due to sample displacement in parallel beam is similar to 
Bragg Brentano mode?
If not then what is the mathematical expression in parallel beam?

Thanks

Shay
--
_

Dr. Shay Tirosh
Institute for Nanotechnology & Advanced Materials
Bar Ilan University
Ramat Gan, 52900
Israel
Phone: +972-(0)30-531-7320
Mobile: +972-(0)54-8834533
Email: stiro...@gmail.com
_

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--
Martin Vickers
Dept. of Chemistry, UCL,
20, Gordon Street
WC1H 0AJ
020 7679 5592 (or ex 25592)
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Re: 2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Martin Vickers 
Hi, Shay. The sample displacement / peak-position relationship is
equivalent.

Martin

On 2 February 2017 at 15:14, Shay Tirosh  wrote:

> Dear Rietvelders
>
> Does the 2-teta shift due to sample displacement in parallel beam is
> similar to Bragg Brentano mode?
> If not then what is the mathematical expression in parallel beam?
>
> Thanks
>
> Shay
> --
> _
>
> Dr. Shay Tirosh
> Institute for Nanotechnology & Advanced Materials
> Bar Ilan University
> Ramat Gan, 52900
> Israel
> Phone: +972-(0)30-531-7320
> Mobile: +972-(0)54-8834533 <+972%2054-883-4533>
> Email: stiro...@gmail.com
> _
>
> ++
> 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/
> ++
>
>
>


-- 
Martin Vickers
Dept. of Chemistry, UCL,
20, Gordon Street
WC1H 0AJ
020 7679 5592 (or ex 25592)
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RE: 2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Radovan Cerny 
Dear Shay,

There is no 2theta shift due to sample displacement in parallel beam geometry. 
That’s why the synchrotron data are so good!

radovan

Radovan Cerny
Laboratoire de Cristallographie, DQMP
Université de Genève
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08
mailto : radovan.ce...@unige.ch
URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm

De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part de 
Shay Tirosh
Envoyé : jeudi 2 février 2017 16:15
À : rietveld_l@ill.fr
Objet : 2-teta shift due to sample displacement in parallel beam

Dear Rietvelders

Does the 2-teta shift due to sample displacement in parallel beam is similar to 
Bragg Brentano mode?
If not then what is the mathematical expression in parallel beam?

Thanks

Shay
--
_

Dr. Shay Tirosh
Institute for Nanotechnology & Advanced Materials
Bar Ilan University
Ramat Gan, 52900
Israel
Phone: +972-(0)30-531-7320
Mobile: +972-(0)54-8834533
Email: stiro...@gmail.com
_
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++

2-teta shift due to sample displacement in parallel beam

2017-02-02 Thread Shay Tirosh 
Dear Rietvelders

Does the 2-teta shift due to sample displacement in parallel beam is
similar to Bragg Brentano mode?
If not then what is the mathematical expression in parallel beam?

Thanks

Shay
-- 
_

Dr. Shay Tirosh
Institute for Nanotechnology & Advanced Materials
Bar Ilan University
Ramat Gan, 52900
Israel
Phone: +972-(0)30-531-7320
Mobile: +972-(0)54-8834533
Email: stiro...@gmail.com
_
++
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