[Ifeffit] Fitting pre-edge feature in Fe XANES

[shbone at berkeley.edu]

Dear All:

I would like to attempt fits to the pre-edge features of a set of Fe
K-edge XANES spectra for Fe(II) samples that show partial oxidation with
the goal of determining whether Fe(III) exists in octahedral or
tetrahedral coordination (e.g. Wilke et al., American Mineralogist, 2001).

Broadly, the fitting procedure involves extracting the pre-edge feature
from the edge using a spline function and then deconvoluting this feature
using a set of pseudo-voigt functions.

I believe that I can use the LCF module in Sixpack to fit the feature
using the pseudo-voigt functions, but I'm having trouble extracting the
pre-edge feature.

I've tried using the spline function in Sixpack (and Athena), but I don't
have enough options to modify the spline. It seems to me that I need to
use a very rigid spline (for instance, one with only 3 or so knots), and
that the options in Sixpack and Athena don't allow for this.

I heard the program exafspak would allow me more freedom to control the
spline function, but I haven't been able to successfully download the
program, let alone use it. So, my questions are the following:

(1) Is there a program other than exafspak that I could use to fit a
spline to my data where I would have more control over the spline options?
I would prefer not to use exafspak since my knowledge of unix is nil.

(2) Has anyone used exafspak on a mac? I'm using OS 10.5.8 and I'd
appreciate any tips you might be able to give me on installing the
program. I followed the directions for installation provided on the
website, but the command to install the program (i.e. "add_exafs") wasn't
recognized.

Thanks for your help!

Sharon