Data Analysis
Refinement of DMC data using FULLPROF
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Fullprof recognizes the DMC data format (Ins=8).
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.
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