On Thursday 29 July 2004 08:49 pm, m.bondin@pgrad.unimelb.edu.au wrote:
Is there any way of determining if this small difference in energy, and hence E0, between the Fe atoms in the clusters can or cannot be neglected in modelling the EXAFS?
The generic answer to this sort of question is that the fit should tell you what the data will support. Are the data well fit in the R-factor sense? Are the fitted values for e0 different outside their error bars? Does the reduced chi-square value decrease significantly when you add the many e0 values? Are the e0 values physcially justifiable? Are the other parameters physically reasonable? At the end of the day you may be inclined to believe a particular fitting model, but not solidly convinced. That is not a failure of analysis (either by the software or by its user), it just means that the data is supported by a particular model, but not conclusively. In that case, I would say it is good science to report your inclination so long as you also report an honest assessment of the data and an honest assessment of your uncertainty in the result. HTH B -- Bruce Ravel ----------------------------------- ravel@phys.washington.edu Code 6134, Building 3, Room 405 Naval Research Laboratory phone: (1) 202 767 2268 Washington DC 20375, USA fax: (1) 202 767 4642 NRL Synchrotron Radiation Consortium (NRL-SRC) Beamlines X11a, X11b, X23b National Synchrotron Light Source Brookhaven National Laboratory, Upton, NY 11973 My homepage: http://feff.phys.washington.edu/~ravel EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/