[Ifeffit] Re: Ifeffit Digest, Vol 1, Issue 121

Matt - it might be sensible to just add a new function to do the rebinning i.e. map mu(E)->mu'(E') on resampled grid (mu data around the edge could be left unchanged). People could call the function ('rebin"?) only they needed it; subsequent routines could be kept as they are now. Anyone who doesn't like the rebinning wouldn't be obligated to use it. thanks - grant On Thu, 13 Mar 2003 ifeffit-request@millenia.cars.aps.anl.gov wrote:

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Today's Topics:

1. RE: Rebinning (Kelly, Shelly D.) 2. Rebinning (Bruce Ravel) 3. Re: Rebinning (Carlo U. Segre) 4. Re: Rebinning (Matt Newville)

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Message: 1 Date: Wed, 12 Mar 2003 13:52:45 -0600 From: "Kelly, Shelly D." Subject: RE: [Ifeffit] Rebinning To: "'XAFS Analysis using Ifeffit'" Message-ID: Content-Type: text/plain; charset="us-ascii"

Hello All,

There seems to be a lot of interest in Rebinning data. I have a perl script that I've written to do the same thing. I thought it might be of interest.

Shelly

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-----Original Message----- From: Newville, Matthew G. Sent: Tuesday, March 11, 2003 2:08 PM To: Carlo.Segre@iit.edu; XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Rebinning

Hi Carlo,

Thanks!! That's wonderful. It seems like this should be an option in spline() and bkg_cl(), and possibly in pre_edge(). I admit to being still a little confused by the goal of the rebinning, especially with respect to loss of resolution. It seems like to use this script, you need to do two things: 1. select an E0. The data will be put at energies that will give an even k-grid with this e0. I think it's inevitable that if e0 changes, you might want to re-bin.

2. assume that the k-grid is small enough that the measurements at independent energies are within the acceptable energy resolution that they can be simply summed.

Is that right?

Would it be OK with you (and everyone else) to have a weighted average replace the boxcar average? For example, at k=12, [E(k+0.05) - E(k)] = 5eV, which is larger than normal energy resolutions, so the boxcar average might wash out the high-k EXAFS, no? It might be better to convolve the spectra with a lorenztian reflecting the incident energy resolution (probably defaulting to 1eV). Does that seem OK or is there something eles going on?

Anyway, thanks!!

--Matt

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