[Ifeffit] Two edge problem (in the same scan)

[Kelly, Shelly D.]

> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov [mailto:ifeffit-
> bounces at millenia.cars.aps.anl.gov] On Behalf Of Bruce Ravel
> Sent: Wednesday, January 26, 2005 1:30 PM
> To: asg2 at lehigh.edu; XAFS Analysis using Ifeffit
> Subject: Re: [Ifeffit] Two edge problem (in the same scan)
> 
> > Hello everybody,
> > I have a question/problem. Last year during the EXAFS course at
NSLS, I
> > had requested Bruce if it is possible to analyze the data with two
> > edges. For example, I have the data for As and Se K-edges, which I
> > collect in the same scan. In WinXAS program, I can section the edges
and
> > analyze them separately. At that time, the program was not able to
> > perform these edges or the sectioning. Have we reached this
possibility.
> > I tried again using the latest updated Athena, but it seems not to
be
> > working. Can you please tell me whether the sectioning or dealing
with
> > two edges in the same spectra can be done
> 
> I don't unfderstand why "sectioning" is necessary.  What precludes you
> from reading the data set a second time and setting e0 to be
appropriate
> for the second edge?  Then your pre- and post-edge lines will be made
> using the second e0 and everything else should just follow normally.
> 
> I understand that Athena does not have a way to specify the second
edge in
> the column selection dialog, but that seems to me like an
inconvenience
> more than a real limitation.  It is an inconvenience because you then
have
> to specify the second e0 by hand rather than have Athena's magic find
it
> for you, but is that really so hard?
> 
> B
> 

[Kelly, Shelly D.] 
Another feature that I have found useful for data with multiple edges is
the truncate function.  Once you read the data set into Arthena.  Make a
copy of the data set.  Choose your e-zero for each data set.  And then
truncate the data sets to the "normal" range.  This will help with some
of the automatic presets, which use the full data range by default, and
can give you a very scary initial background function.

SK