Thanks Jon, Luca and Jeremy,
Much appreciate for your info and comments!
Yours,
Tony:)
Sent from Mail Master
On 06/12/2015 00:25, Luca Lutterotti wrote:
John is correct, be careful that you are trying to compare same quantities but
in a completely different units and definitions. I discover by myself that you
cannot mix scattering factors, absorption factors, photo absorption etc. coming
some from the diffraction community and some from the spectroscopic community.
So Henke is used by the spectroscopic community (second link) and need proper
conversion to be applied for scattering…..
I actually use Henke derived work in Maud now as I can compute the dispersion
coefficients (and absorption) for every wavelength not only the tabulated ones
usually adopted in diffraction, but I had to convert everything to be
consistent (absorption etc.).
Best regards,
Luca
On Jun 11, 2015, at 6:07 PM, Jonathan WRIGHT <wri...@esrf.fr> wrote:
Dear Xiaodong, Jeremy,
Isn't it equation 3 here?
http://www.nist.gov/srd/upload/jpcrd488.pdf
f1/f2 are "dispersion" numbers and f'/f" are the "anomalous" ones. The
relativisitic correction number for iron then shows up on page 221.
Best,
Jon
===
On 11/06/2015 17:27, Jeremy Karl Cockcroft wrote:
Hi Xiaodong,
I think that the numbers quoted for f' in the second case have had 26e (atomic
no.) added to them, i.e. it refers to the total dispersion value for the real
component (as opposed to the imaginary component). Given that the numbers
quoted are close to an absorption edge, then the remaining differences are not
unexpected depending on source and precise energy quoted. If graphs of the data
are plotted with Z subtracted, then they look very similar apart from the
precise value of the minimum of f' at the absorption edge itself.
Just my thoughts on it...
Jeremy Karl.
***************************************************************
Dr Jeremy Karl Cockcroft
Department of Chemistry
(University College London)
Christopher Ingold Laboratories
20 Gordon Street
London WC1H 0AJ
United Kingdom
+44 (0) 20 7679 1004 (laboratory)
j.k.cockcr...@ucl.ac.uk or jeremyk...@gmail.com
http://img.chem.ucl.ac.uk/www/cockcroft/homepage.htm
***************************************************************
On 11 June 2015 at 15:33, iangie <ian...@126.com> wrote:
Dear Rietvelders,
I am little confused about the term "Anomalous scattering factor" and
"Dispersion coefficients".
"Anomalous scattering factor" can be found here
http://skuld.bmsc.washington.edu/scatter/AS_form.html
"Dispersion coefficients" can be found here
http://www.cxro.lbl.gov/optical_constants/asf.html
Their numbers are quite different: e.g. Fe @ CrKα: f0=18.474, Δf'=-1.6 Δf"=0.9
; however, the corresponding dispersion coefficients are f' ~24.6808 and f"
~0.759346
Can anyone explain their relationship?
Thanks!
--
Yours Sincerely,
Dr. Xiaodong(Tony) Wang
XRD Application Scientist
Bruker Singapore Pte. Ltd.
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