Jon,
What you have here may be the classic "rocks and dust" problem. Doing it as
two phases might therefore be appropriate. It's a little painful as you
will need to put in a lot of constraints to tie the two phases together.
This will still work OK with your combined data refinement.
Bob Von Dreele
At 07:54 PM 3/21/00 +0000, you wrote:
>Hi all,
>
>I've got some high resolution data from a synchrotron with quite a lot of
>sample broadening. A quick go with a curve fitting program has shown that
>the fitting a pseudo-voigt peakshape leads to a negative eta parameter. So
>it is more that 100% "lorentzian" in character. I can get quite nice fits
>to individual peaks with a sum of two lorentzians, or with the strange
>pseudo-voigt. To refine the data I want to give a peakshape like this to a
>Reitveld refinement program.
>
>Can this be done with GSAS without using more than one crystallographic
>phase? As far as I can tell the answer is no - can anyone tell me
>otherwise or lend any handy hints? I'd like to be doing a combined fit of
>this data with some high resolution TOF neutron data at some point in the
>future, which seems to rule out many other programs.
>
>Pointers to source code for a suitable peakshape (with an low angle
>asymmetry correction) would be also be appreciated.
>
>Thanks in advance,
>
>Jon Wright
>
>============================================================================
> Dept. of Chemistry, Lensfield Road, Cambridge, CB2 1EW
> Phone-Office 01223 (3)36396; Lab 01223 (3)36305; Home 01223 462024
