Thank you Sir Bruce Ravel

I am using laser plasma X-ray source that emits Cu kalpha and Kbeta together with Bremsstrahlung. I am working with Ni sample whose edge falls between K alpha and K beta lines. I am recording the signal on CCD screen through graphite spectrometer in such a way that part of the beam is being transmitted through the sample while other portion is going direct to the ccd. In other words I have monitoring/Reference and transmitted signal simultaneously on CCD. The setting is such that I can record Cu kalpha together with K absorption edge of Ni always in above mentioned singals. I am interested in K edge.

Now while performing pump probe experiment, as i mentioned in previous message, there happens a shift of K edge. Additionaly sometimes the drift of the signal is observed on the screen. Now comes the alignment of the spectra to deal with the possible drift. 

My question is this that should I align the spectra with reference to Cu K-alpha line of monitoring beam? or should I align the spectra with each other (transmitted signal of one spectra to the other) taken on different delays? I hope you understand my question and hope to see the valuable solution.

Best Regards


From: Bruce Ravel <bravel@bnl.gov>
To: mazhar iqbal <mazharphy_05@yahoo.com>; XAFS Analysis using Ifeffit <ifeffit@millenia.cars.aps.anl.gov>
Sent: Tuesday, May 31, 2016 9:22 PM
Subject: Re: [Ifeffit] Regarding time resolved XAS

On 05/30/2016 02:20 AM, mazhar iqbal wrote:
> I want to ask about the aligning the XAS spectra that is given in
> Athena. Can we do the alignment of time resolved spectra? As you know
> that the resolved spectra (IR pump X-ray probe) may have edge shift due
> to laser pumping. Do you think that the same method of the alignment can
> be applied here as well. An additional piece of information is that  we
> have a reference fluorescence line always on the screen that well behind
> the K absorption edge.

Well, you have told us what you have tried nor what problem you are
actually facing.  If the question is "does Athena help you align data?"
  I think you already know that the answer is yes.

I don't understand the business about a "fluorescence line always on the
screen".  How do you propose to use that to align your XAS data?

In the case of a situation where you are purposefully changing the
chemical state of the sample, then you need to have some absolute
reference by which to perform the alignment -- a reference spectrum
measured simultaneously, an encoder reading on the monochromator,
something that allows you to do the chore.

You question is a bit vague and open-ended.  Without more information or
a more focused question, I don't know how to help you further.


B



--
  Bruce Ravel  ------------------------------------ bravel@bnl.gov

  National Institute of Standards and Technology
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