> ... not at all for magnetism, ...
Ahem, magnetism - resolution is very useful, in certain (rare) cases. I
guess that magnetic structures are not Armel's primary interest
but in at least one case resolution was essential. (FeAsO4 from IRIS (TOF
neutron) dataset, J.Phys:Condens.Matter 11 (1999) 1
>And the question is really : if I do not succeed at home, can I really
>succeed on a big instrument ? I think yes if those numbers mean
>really something. Hence the need to define what they mean.
And the last numbers are, in 'equivalent conventional X-ray at 1.54A
units' of FWHM, which really me
Lubo wrote:
>why do you like playing with numbers so much ? Well, I can tell you some
>more :
>suppose you can subdivide your (our) interval (0-180 degs 2theta) into
>small parts, say 0.01 degs. In other words, you may have 18 channels
>at maximum. If there is an "useful" intensity in a chann
Armel,
why do you like playing with numbers so much ? Well, I can tell you some
more :
suppose you can subdivide your (our) interval (0-180 degs 2theta) into
small parts, say 0.01 degs. In other words, you may have 18 channels
at maximum. If there is an "useful" intensity in a channel (not onl
>I converted the data to 2th, using a popular synchrotron
>wavelength (0.7 A) for everybody's convenience. You can see by yourself
>that the 200 peak has about 0.013 degrees FWHM. Clearly, the FWHM depends
>on the wavelength you choose, so I guess I could have gotten to 0.006 using
>a shorter wa
Having read all these messages about the merits and advantages of neutron
TOF and synchrotron X-ray powder diffractometers for structure
determination & refinement, I'm a little reminded of the Mac vs PC
arguments that sometimes rage around. Each of these machines have
particular applications that
Oops. I meant http://www.ill.fr/dif/hrpd-mgo.txt
Paolo
Dear Frank,
I've just received an e-mail from the Rietveld mailing list courtesy of
Paolo Radaelli that has an HRPD diffraction pattern of MgO - it's big but
hopefully you will be able to plot the file. This should help you get a feel
for the data and the nature of the binning.
Now concerning th
Dear All,
so that we don't have to wait until Bill comes back...
I sent a portion of an MgO pattern taken with HRPD to Alan, and he kindly
put it on his www server: http://www.ill.fr/dif/hrpd-mgo.doc. It's a simple
text file. I converted the data to 2th, using a popular synchrotron
wavelength
As a user of conventional laboratory powder XRD equipment, I too would
like to "touch with my fingers such a wonderful powder pattern" (nice,
Armel).
I accept visually as a peak one which has five (5) adjacent points
observed above background. With a peak having breadth of 0.006 degree,
the effe
I know that Armel likes to be a little provocative sometimes (who doesn't
:-) but there are many people on the neutron mailing list who are only too
happy to be convinced that X-rays can do it all. Then they can use the
money instead to build the latest version of their fancy spectrometer for
mea
At 11:33 24/09/99 +0100, Kenneth wrote:
>As ever, none of Armel's replies actually acknowledge
>the validity of their resolution arguments
So, I want to acknowledge Brian Toby who pointed
that the best minimal FWHM for a neutron powder
diffractometer at constant wavelength was 0.12° (2-theta
Dear All,
Erich Kisi got it right for saying that the
discussion should be on a scientific basis.
My original posting did not bring up the subject
of structure solution / refinement.
I simply pointed out that Armel's posting to the neutron
list, deprecating the resolution of neutron
instrumen
At 09:18 24/09/99 +1000, Dr Erich Kisi wrote:
>My thanks to Bill David when he wrote:
>
>>I guess that I should try to clarify a couple of points about structure
>>determination from neutron powder diffraction and about the resolution of
>>neutron powder diffractometers.
>>etc, etc,etc
>
>for put
My thanks to Bill David when he wrote:
>I guess that I should try to clarify a couple of points about structure
>determination from neutron powder diffraction and about the resolution of
>neutron powder diffractometers.
>etc, etc,etc
for putting the resolution/structure solution discussion on a
I guess that I should try to clarify a couple of points about structure
determination from neutron powder diffraction and about the resolution of
neutron powder diffractometers.
(i) Structure determination from neutron powder diffraction
Armel is quite right when he says that you see all the ato
It is not usual to reply to a mail on another mailing list than
the original.
Fortunately I am a subscriber of both the Rietveld and neutron
mailing lists.
Anyway, no, it is not a joke.
On about 400 structure determinations from powder diffraction
data, less than 5% were done from neutron data,
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