Re: Absorption correction neutrons / x-rays

Alan Hewat, ILL Grenoble ( (no email) )
Sat, 25 Oct 1997 10:44:10 +0200

joubert@titan.cnrs-bellevue.fr wrote 23 October 1997:

>- you must keep always in mind that, like for X-ray in Debye-Scherrer
>geometry, the value of muR must be kept below 1 because the fomula used in
>Rietveld programs known as Hewat fomula (eg Fullprof) is only valid in that case

BTW, there is a factor of 2 missing in my paper (Acta Cryst. (1979) A35, 248
"Absorption corrections for neutron diffraction") , so if you actually want to
calculate the change to the overall DW factor, please check my arithmetic :-)

As Jean-Marc Joubert says, unless you had strongly absorbing atoms in your
sample (not usual for neutrons cf X-rays), the absorption only changes this
overall Debye-Waller factor, so fancy corrections are unecessary; you will
not further improve the fit with an absorption correction (but you will improve
the DW-factor).

Alan Hewat, ILL Grenoble, FRANCE <hewat@ill.fr> tel (33) 4.76.20.72.13
ftp://ftp.ill.fr/pub/dif fax (33) 4.76.48.39.06 http://www.ill.fr/dif/