Dear Rietveld Users,
I am currently trying to work with TOF (HRPD – ISIS) data with Fullprof.
In order to learn more about the diffractometer and the profile I have
started with a standard : the CeO2 Sharp from the Round Robin (Balzar).
I have done a pattern matching refinement, but I fell that my profile is
not so great Rwp around 15%.
I have read the nice and pedagogical Chapter 4 from Neutron Rietveld
Refinement from R.B. Von Dreele in the Reviews in Mineralogy (n°64) and
the Fullprof manual but I am still lost.
The profile in TOF is really more complicated than a simple pseudo-Voigt
function !
My questions / requests:
- I have the gamma values in the IRF and the PCR file, but in the Edit
Pcr I am unable to get them ?
- Instrumental resolution function for HRPD/ISIS L. Chapon 12/2003
- ! To be used with function NPROF=9 in FullProf (Res=5)
- ! ---------------------------------------------------- Bank 1
- ! Type of profile function: back-to-back expon * pseudo-Voigt
- NPROF 9
- ! Tof-min(us) step Tof-max(us)
- TOFRG 15000.0000 1.0000 115000.00000
- ! Dtt1 Dtt2 Zero
- D2TOF 48288.88670 -4.66859 -3.015
- ! TOF-TWOTH of the bank
- TWOTH 168.33
- ! Sig-2 Sig-1 Sig-0
- SIGMA 0.736 120.766 0.000
- ! Gam-2 Gam-1 Gam-0
- GAMMA 0.000 4.095 0.000
- ! alph0 beta0 alph1 beta1
- ALFBE 0.000000 0.024506 0.152657 0.012394
- END
Sig-2 Sig-1 Sig-0 Xt Yt Z1 Z0 Size-Model
! 0.736 318.676 -66.849 <- Instr. par. + shifts. Only shifts are
refined
0.000 197.910 -66.849 0.000 0.000 0.000 0.000 0
0.00 71.00 81.00 0.00 0.00 0.00 0.00
! Gam-2 Gam-1 Gam-0 LStr LSiz
! -3.682 16.132 0.000 <- Instr. par. + shifts. Only shifts are
refined
-3.682 12.037 0.000 0.000 0.000
0.00 0.00 0.00 0.00 0.00
- For HRPD there is an IRF file with NPROF =9, is it possible to use
NPROF =13 and if yes, does anyone have such IRF file ? or how create
such file ?
- For constant wavelength, we can use a special order for the refinement
variables /Scale/Flat Background/W/Eta…. Is there any same rules for TOF
refinement ?
- Does anyone have done such works with GSAS on the same data ?, in
order to compare the reliability factors.
Thanks in advance,
--
Dr. François Goutenoire
Maître de Conférences, IUT Le Mans
Laboratoire des Oxydes et Fluorures, UMR6010
Avenue Olivier Messiaen,
72085 Le Mans, Cedex 9
