Data Analysis

Refinement of DMC data using FULLPROF

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Fullprof recognizes the DMC data format (Ins=8).
Example for Npr=4 (click to enlarge)
Example for Npr=4 (click to enlarge)
Best fits are achieved using profile function 4 (Npr=4) in Fullprof. Besides U,V and W this peak shape requires 4 additional parameters (Shape1, X, Y, Shp1).

These parameters are instrument parameters and should not be refined. At λ = 2.45 Å we get Shape1=0, X=0.2849, Y=0.3657, Shp1=0.00787. The parameters U,V and W depend on the sample and must be refined. Possible starting values at 2.45 Å are 0.94, -0.57, 0.18. See the table below for the list of peak shape parameters at other wavelengths. It is advised to set Wdt, the cut-off of the peak profile tails, to a small number, e.g. Wdt=3.

Example of a refinement: pcr file, data file, plot


You may as well use other profile functions, e.g. peak shape function 7 (Npr=7, see Fullprof manual). This will lead to quite similar values of the refined structural or magnetic parameters but with somewhat larger errors.
Peak shape parameters for peak shape function 4 (Npr=4)
Wavelength Shape1 X Y Shp1 U3) V3) W3)
2.45 Å 0 0.39068 0.35013 0.007046 1.03 -0.63 0.21
3.80 Å SD 1) 0 0.33132 0.34197 0.00575 0.62 -0.68 0.39
3.80 Å LD 2) 0 0.31362 0.37559 0.00560 0.45 -0.40 0.23
4.20 Å SD 1) 0 0.33522 0.33866 0.00544 0.46 -0.44 0.29
4.20 Å LD 2) 0 0.31712 0.35498 0.00548 0.46 -0.44 0.29
4.50 Å SD 1) 0 0.31415 0.32137 0.00521 0.45 -0.43 0.31
4.50 Å LD 2) 0 0.36928 0.39220 0.00462 0.42 -0.39 0.30
1) short distance, 2) long distance, 3) possible starting values for the refinement





Old parameters, before 2014:
Peak shape parameters for peak shape function 4 (Npr=4)
Wavelength Shape1 X Y Shp1 U3) V3) W3)
2.45 Å 0 0.2849 0.3657 0.00787 0.94 -0.57 0.18
3.80 Å SD 1) 0 0.3443 0.3156 0.00583 0.75 -0.81 0.35
3.80 Å LD 2) 0 0.4631 0.3970 0.00477 0.48 -0.33 0.20
4.20 Å SD 1) 0 0.3620 0.3385 0.00536 0.55 -0.58 0.35
4.20 Å LD 2) 0 0.4381 0.4092 0.00457 0.38 -0.15 0.17
4.50 Å LD 2) 0 0.4386 0.3904 0.00437 0.31 -0.12 0.18
1) short distance, 2) long distance, 3) possible starting values for the refinement

Contact

Instrument responsible
Keller, Lukas Dr.
Phone: +41 56 310 4007
E-mail: lukas.keller@psi.ch

Instrument office
Room WNLA/104
Phone: +41 56 310 3184

Instrument area
Phone: +41 56 310 3683

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