Hello All,
I am looking for thoughts and opinions regarding the best way to
approach post-edge fitting and normalization of C and N NEXAFS data. I
know soft x-rays aren't exactly the focus of the list, but it is still
the best access to a lot of people with a lot of XAS knowledge, and I
would be very interested in your opinions.
Obviously, linear or quad curve fitting followed by normalization is
standard and well accepted for hard x-ray spectra.
However, as far as I can tell there is no such accepted norm of C and N
NEXAFS treatment. I have seen that some groups use a single point
normalization, e.g. 310 for the case of C, and simply divide through the
entire spectrum with this value. Other groups take the min and max
value of the spectrum and map it onto a 0 to 1 scale. Neither of these
approaches seems satisfactory to me for data with obvious backgrounds
like those attached. While these data are not perfect, it seems like
they should definitely be useable.
My thought is why not do a 'standard' hard x-ray type normalization like
that shown with an e0 set to the theoretical ionization potential for C
or N. I understand that this has problems with the potential of
including tailing sigma* transitions or first EXAFS oscillations in the
background region because it doesn't extend far enough beyond the edge.
However, it seems to me an approach like this must be 'less-wrong' than
the more simplistic methods mentioned above and capable of yielding
useful data.
Thoughts, comments, jeers? --Peter
