Hi Peng: The answer is yes, you can use a variable called "n" or n_o" but you need to be careful on how you set up the fitting. here is one way to do it: For the path of interest, in the two boxes which are labeled "N" and "S02", you fill them in as "1" and "n_o" (for number of oxygens for example). Then you let "n_o" (note that at least in Artemis, lower case is the same as upper case in variables) vary as a guess parameter. The result will be a number that is of the order of the number of near neighbors but it will be too large by the factor of one over the amplitude reduction factor. If you have a way to estimate the amplitude reduction factor as a set variable called "amp" you can set up the model a bit differently, putting "amp * n_o" in the "S02" box. This might give a better estimate of the coordination number (path degeneracy). Note that numerically there is no difference between the above and taking a guessed value of "amp" and multiplying it by the number in the "N" box. It is simply a matter of convenience and ease of looking at the output. Carlo On Sat, 26 Jul 2014, Peng Liu wrote:
Hi all,
When I model a standard, I know the degeneracy through the other data. But for spectra of unknown material, I would like to set degeneracy as a variable like the amplitude, deltE0, e.g.. However, I can assign a letter to N and define it. Do you have any idea how I should do it?
Thanks for your reply,
Peng
-- Carlo U. Segre -- Duchossois Leadership Professor of Physics Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org