zhouxiuquan
Hello,
I have a question regarding refinements of TOF data with TOPAS and GSAS. We were not able to get as good refinement in TOPAS as in GSAS, and we used the two exponential functions as described in TOPAS WIKI topics :
" TOF_Exponential(a0, 100, ,0, 1, t1, -)
TOF_Exponential(b0, 100, b1, 100, 4, t1, +)"
However, intensities and the peak shape from TOPAS were off, while they visually fit well in GSAS. I was wondering how different is this profile from the the profile in GASA. In addition, is there a macro for GSAS TOF profile in TOPAS.
Thank you very much!
Sincerely,
Zhou
zhouxiuquan
Hi Alan,
Thank you very much! I did not expect a reply so soon, and I really appreciate this. It seems that the issue has been resolved, and we do get a pretty good fit with TOPAS now, although I still have a few questions. When refining TOF data, which of the two macros: TOF_Exponential() and TOF_PV() can provide a better fit for the profile?
Thanks again for your help!
Sincerely,
Zhou
alancoelho
Typically both TOF_PV and TOF_Exponential would be used, see test_examples\TOF_Bank2_1.inp. This particular example fits to a simulated GSAS pattern.
The phase dependent TOF_PV macro signals that the peak type to be used is a pseudo-Voigt which varies as a function of D_spacing. The TOF_Exponential macro convolutes a decaying exponential into the pseudo-Voigt.