Using q range instead of 2Th

levkhait

Hello everyone!

I have some synchrotron data in ".xy" format, where the X-axis is in q-range instead of 2Th. I can transform it to 2Th outside of Topas, but I was wondering if there is a way to work with it directly in the input files.

I found a similar question on the forum, but the link in the replies does not open: https://topas.awh.durham.ac.uk/flarum/public/d/288-import-data-in-q-space

Thanks for your time!

Lev

rowlesmr

yes you can. I need to have a look at my ED input files to check the exact notation.

rowlesmr

Look up pk_xo

[pk_xo E]
Provides a mechanism for transforming peak position to an x-axis position.
The peak position for neutron time-of-flight data is typically calculated in time-of-flight space, tof, or:
tof = t0 + t1 dhkl + t2 dhkl2
where t0 and t1 and t2 are diffractometer constants. pk_xo can be used to refine TOF data.

johnsoevans

I was talking to Alan about this at epdic today. He commented that you may need to change the extra_X_right value that extends the range slightly so all necessary peaks are included. The default value assumes 2th and is 0.5 which may not be appropriate for q.