>>Its best to use the terms axial plane and horizontal plane to avoid
>>confusion.
>
>Alan, I'm confused! What do you mean by those terms?
>I thought "axial divergence" was "beam hits
>different points along the two theta axis" -
>is that a misconception?
John, if you had a point source, a poi
Its best to use the terms axial plane and horizontal plane to avoid
confusion.
Alan, I'm confused! What do you mean by those terms? I thought "axial
divergence" was "beam hits different points along the two theta axis" -
is that a misconception?
Last point, what do you mean by vertical diver
Jim Cline wrote:
>Alan??? Are you listening?
Armel wrote:
>>Bruker providing help to analyze Panalytical data ?-).
You have thrown the bait and I will bite.
I am not an employee of a manufacture and as such I am free to implement
as I choose into TOPAS-Academic (TA) and I do this without regard
On 3 May 2005 at 10:51, Jon Wright wrote:
> >
> Silly question and I think I am missing the point - but how did you fix
> the vertical divergence contribution? I thought LaB6 from NIST had a
> larger crystallite size than either of your values, suggesting something
> has gone wrong in both case
I did some tests on the profile of the first diffraction peak of LaB6,
where I added a secondary soller angle, since I used secondary
soller slits, and I added also the parameter for the horizontal
divergence in the equitorial plane. Finally I added a crystallite-size
parameter CS_L. I did the
Laurel Basciano wrote:
> >xdd "test.dat"
> > CoKa7_Holzer(0.001)
> > Radius(240)
> > LP_Factor(17)
> > axial_conv
> > filament_length 12
> > sample_length 15
> > receiving_slit_length 12
> > primary_soll
Arie,
Yes; Bruker has an interest in this matter.
Jim
At 09:37 AM 5/2/2005, you wrote:
Bruker's Vantex detector is rather similar to PanAnalytical's
X'celerator detector from a fundamental parameters point of view,
not? Maybe I should have formulated my question differently
Is there anybody who kno
Laurel,
At 09:13 AM 5/2/2005, you wrote:
Hi,
Alan Coelho helped us get our instrument parameter file set up for Topas
Academic. We use an X'celerator detector with cobalt radiation (no
monochromator) for most of our work.
Here is an example file:
xdd "test.dat"
CoKa7_Holzer(0.001)
Bruker's Vantex detector is rather similar to PanAnalytical's
X'celerator detector from a fundamental parameters point of view,
not? Maybe I should have formulated my question differently
Is there anybody who knows how to model peak shapes using the
fundamental parameters approach for diffracto
Hi,
Alan Coelho helped us get our instrument parameter file set up for Topas
Academic. We use an X'celerator detector with cobalt radiation (no
monochromator) for most of our work.
Here is an example file:
xdd "test.dat"
CoKa7_Holzer(0.001)
Radius(240)
LP_Factor(17)
Indeed...
A situation not without some complications.
Jim
At 08:00 AM 5/2/2005, you wrote:
Alan??? Are you listening?
Bruker providing help to analyze Panalytical data ?-).
Armel
James P. Cline [EMAIL PROTECTED]
Ceramics Division Voice (301)
Alan??? Are you listening?
Bruker providing help to analyze Panalytical data ?-).
Armel
Arie,
Bob Cheary developed the required description/equations for the use of a
psd. But I don't know that they have been implemented in any of the
available FPA codes, except perhaps Topas in launch mode.
Alan??? Are you listening?
Regards,
Jim
At 06:48 AM 5/2/2005, you wrote:
Dear colleagues,
Pamela,
At 10:24 07.06.2004 -0400, you wrote:
>In a perfect world this would be the case, but given that very few people
>run systems that conform to the requirements for true fundamental parameters
>(Bragg-Brentano with NO monochromator, mirrors, etc), then one is not really
>using fundamental par
Oooo, picking up where Friday left off..
Must go and put the coffee pot on :-)
- refining of "fundamental parameters" is nonsense, unless one is not
familiar with his diffractometer or want/must "absorb" any unkown effects
or weaknesses of his model :-)
In a perfect world this would be the c
Hi Jon and Pamela,
my very personal opinion regarding the "fundamental parameter" stuff:
- fundamental is that the observed peak shape is a folding of contributions
from (i) wavelength distribution, (ii) instrumental/geometrical aberations
and (iii) microstructure of the sample. From this point of
>In addition, the raytracing fundamental
>approach describes at now (planar) transmission geometry and
>capillar geometry.
Don't know about the planar transmission (never done it), but I can happily
fit capillary data off my system. I have no quibbles about the
effectiveness of ray-tracing, but w
Dear all,
just a remainder for a less popular (and, sorry, less academic
published) fundamental parameters aproach: raytracing the
geometric part of fundamental parameters as done in BGMN
www.bgmn.de
(download a free trial version at www.bgmn.de/download.html).
At my opinion, folding the geometri
Our system has double mirrors and I could never get FCJ to give as good a
fit, but then that may be a peculiarity of these optics. My memory is a bit
hazy so I can't remember what function the simple axial model uses, but I
don't think it's a function of diffractometer characteristics. Topas is
f
Hi all,
Here are the references to these papers:
Cheary RW, Coelho AA (1998a) Axial divergence in a conventional X-ray powder
diffractometer. I. theoretical foundations. J. Appl. Cryst. 31:851-861
Cheary RW, Coelho AA (1998b) Axial divergence in a conventional X-ray powder
diffractometer. II. Re
In Topas there are two options for treating low-angle asymmetry using
diffractometer characteristics (i.e., "fundamental parameters") called
"simple axial model" and "full axial model". But (this is my impression
only) it seems that FCJ (Finger et al) approach works equally well.
Starting from Topa
Nandini
If you're using standard Bragg-Brentano the true fundamental parameters
fitting from first principles will happily fit low angle asymmetry, as the
mathematical basis for it is well known (look for some papers that Alan
Coehlo and Bob Cheary did a while back, in J.Appl.Cryst I think). Axia
Thanks, Pam and Jon for the clarifications.
Again, does this approach take care of low angle peak
asymmetry better?
thanks,
nandini
--- "Whitfield, Pamela"
<[EMAIL PROTECTED]> wrote:
> Nandini
>
> The best people to reply on behalf of fundamental
> parameters would be Alan
> Coehlo or Arnt Kern
Is the fundamental parameter approach better than
mathematical approach used in most of the Rietveld
refinement programs?
Perhaps someone is about to explain the difference is between
"fundamental parameters" and anything else? I used to think it might
mean convoluting something which was actu
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