[Ifeffit] Ifeffit Digest, Vol 159, Issue 4
Matteo Busi
basebush at gmail.com
Sat May 14 18:20:03 CDT 2016
Dear Chris,
I would be glad to at least read the papers you mentioned. If it possible
you can send them here or at my email basebush at gmail.com when you have time.
Regards,
Matteo
Den lørdag 14. mai 2016 skrev <ifeffit-request at millenia.cars.aps.anl.gov>
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> 1. Re: Ifeffit Digest, Vol 159, Issue 3 (Christopher Thomas Chantler)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 13 May 2016 21:43:34 +0000
> From: Christopher Thomas Chantler <chantler at unimelb.edu.au <javascript:;>>
> To: "ifeffit at millenia.cars.aps.anl.gov <javascript:;>"
> <ifeffit at millenia.cars.aps.anl.gov <javascript:;>>
> Cc: Christopher Thomas Chantler <chantler at unimelb.edu.au <javascript:;>>
> Subject: Re: [Ifeffit] Ifeffit Digest, Vol 159, Issue 3
> Message-ID:
> <
> 1C86B7F795364B44940B1EAAB9D774FADEE724BE at 000s-ex-mbx-qs1.unimelb.edu.au
> <javascript:;>>
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> Content-Type: text/plain; charset="us-ascii"
>
> Dear All, Matteo
>
> It is difficult to do post facto, but if you have a well-defined solid,
> foil or crystal then mapping the thickness, measuring the mass and hence
> determining the mass per unit area, for the exact region illuminated by the
> beam, provides accurate units. Usually you will need to make a measurement
> of the average m/A from (i) total mass and (ii) total area, and then (iii)
> map the whole sample with X-ray tomography and (iv) the region illuminated
> by the X-ray beam.
>
> We have a series of papers which explain more than one methodology for
> doing that within the XERT technique. If your sample is a solution it is a
> bit more tricky, and I would refer you to recent JSR and JPCC papers for
> our Hybrid technique. Both can work well but need a bit more care than a
> normal XAFS measurement.
>
> Best wishes
> Chris
> ------------------------------------------------------------
> Christopher Chantler, Professor, FAIP
> Editor-in-Chief, Radiation Physics and Chemistry
> Chair, International IUCr Commission on XAFS
> President, International Radiation Physics Society
> School of Physics, University of Melbourne
> Parkville Victoria 3010 Australia
> +61-3-83445437 FAX +61-3-93474783
> chantler at unimelb.edu.au <javascript:;> chantler at me.com <javascript:;>
> http://optics.ph.unimelb.edu.au/~chantler/xrayopt/xrayopt.html
> http://optics.ph.unimelb.edu.au/~chantler/home.html
>
>
> ________________________________________
> From: Ifeffit [ifeffit-bounces at millenia.cars.aps.anl.gov <javascript:;>]
> on behalf of ifeffit-request at millenia.cars.aps.anl.gov <javascript:;> [
> ifeffit-request at millenia.cars.aps.anl.gov <javascript:;>]
> Sent: Saturday, 14 May 2016 3:00 AM
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> Subject: Ifeffit Digest, Vol 159, Issue 3
>
> Send Ifeffit mailing list submissions to
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> Today's Topics:
>
> 1. How to assign measure unit to XAFS data (Matteo Busi)
> 2. Re: How to assign measure unit to XAFS data (Alexey Boubnov)
> 3. Re: How to assign measure unit to XAFS data (Matt Newville)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 13 May 2016 02:11:39 +0200
> From: Matteo Busi <basebush at gmail.com <javascript:;>>
> To: ifeffit at millenia.cars.aps.anl.gov <javascript:;>
> Subject: [Ifeffit] How to assign measure unit to XAFS data
> Message-ID:
> <CAOyEiGg1N7wL-tnzPXFBCrUYQD=6=
> bvsRFnDNEe3ZaCeguFU5Q at mail.gmail.com <javascript:;>>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Bruce, Matt, and mailing list readers,
>
> I have one question regarding the XAFS data. I have collected absorption
> coefficient in fluorescence regime of a CuSO4 penta hydrate sample(however
> my question can be generalized to any compound).
> Through Athena I then obtained the x\mu(eV) spectra as well as \chi(k) and
> \chi(R). I am wondering how can I assign a unit to the x\mu values. I would
> like to have it in the cm^-1 or cm^2 kg^-3 unit so than I can match it with
> tabulated data for the Copper absorption coefficient and proceed with my
> studies.
>
> In case a treatment is needed for the normalized \mu , that would also suit
> my situation.
>
> My idea was to divide by the thickness of the sample but I don't find a
> reasonable justificiation for this.
>
> I really hope I made the question clear to any reader this time, and if
> that is not the case I apologyze in advance.
>
> Best Regards
> Matteo
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> Message: 2
> Date: Fri, 13 May 2016 08:29:15 +0200
> From: Alexey Boubnov <alexeyboubnov at gmail.com <javascript:;>>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov
> <javascript:;>>
> Subject: Re: [Ifeffit] How to assign measure unit to XAFS data
> Message-ID:
> <
> CAJZPK0VrRQ2Ad-Mxr2q4kdZorjdT_ceaVroPO3m57LYuS_CiAg at mail.gmail.com
> <javascript:;>>
> Content-Type: text/plain; charset="utf-8"
>
> Dear Matteo,
>
> ?x that you measured is dimensionless: x in the thickness (in cm) and ? the
> Absorption coeffiecient (per cm). Indeed, if you want to know the
> Absorption coefficient ? of your sample, you should divide ?x by x.
>
> All the best,
> Alexey
>
> 2016-05-13 2:11 GMT+02:00 Matteo Busi <basebush at gmail.com <javascript:;>>:
>
> > Hi Bruce, Matt, and mailing list readers,
> >
> > I have one question regarding the XAFS data. I have collected absorption
> > coefficient in fluorescence regime of a CuSO4 penta hydrate
> sample(however
> > my question can be generalized to any compound).
> > Through Athena I then obtained the x\mu(eV) spectra as well as \chi(k)
> and
> > \chi(R). I am wondering how can I assign a unit to the x\mu values. I
> would
> > like to have it in the cm^-1 or cm^2 kg^-3 unit so than I can match it
> with
> > tabulated data for the Copper absorption coefficient and proceed with my
> > studies.
> >
> > In case a treatment is needed for the normalized \mu , that would also
> > suit my situation.
> >
> > My idea was to divide by the thickness of the sample but I don't find a
> > reasonable justificiation for this.
> >
> > I really hope I made the question clear to any reader this time, and if
> > that is not the case I apologyze in advance.
> >
> > Best Regards
> > Matteo
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov <javascript:;>
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
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> >
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> ------------------------------
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> Message: 3
> Date: Fri, 13 May 2016 07:13:08 -0500
> From: Matt Newville <newville at cars.uchicago.edu <javascript:;>>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov
> <javascript:;>>
> Subject: Re: [Ifeffit] How to assign measure unit to XAFS data
> Message-ID:
> <
> CA+7ESbq84ZpYx9DvP8JvM7yNzO0U31jFCZZ-_X43b21sM43+og at mail.gmail.com
> <javascript:;>>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Matteo,
>
>
> On Thu, May 12, 2016 at 7:11 PM, Matteo Busi <basebush at gmail.com
> <javascript:;>> wrote:
>
> > Hi Bruce, Matt, and mailing list readers,
> >
> > I have one question regarding the XAFS data. I have collected absorption
> > coefficient in fluorescence regime of a CuSO4 penta hydrate
> sample(however
> > my question can be generalized to any compound).
> > Through Athena I then obtained the x\mu(eV) spectra as well as \chi(k)
> and
> > \chi(R). I am wondering how can I assign a unit to the x\mu values. I
> would
> > like to have it in the cm^-1 or cm^2 kg^-3 unit so than I can match it
> with
> > tabulated data for the Copper absorption coefficient and proceed with my
> > studies.
> >
>
>
> The analysis tools treat "xmu" as a dimensionless value. To get values
> for the mu in cm^-1 or grm/cm^2, you'll have to convert the measured values
> used for XAFS analysis (say, readings from ion chambers) into actual X-ray
> intensities, and try to account for anything else in the beam path that
> will attenuate the X-rays. For measurements made in transmission, this can
> be done. In fact, for most transmission measurements, the *change* in
> -ln(I0 / I1) is usually a very good measure of the change in absorption of
> the sample, so that if the observed jump is a value of 2, the sample really
> did change its absorption by Delta_xmu = 2. But the absolute values for
> xmu are definitely not in meaningful units. Typically, the photo-current
> from the ion chamber or diode is converted to a voltage and then summed
> over some time period in a data acquisition system. You'd have to know
> the details of that system to convert the "I0" and "I1" numbers into actual
> beam intensities.
>
> For fluorescence measurements, the situation is worse. You'd need a very
> good measure of the solid angle of your detector, fluorescence efficiency,
> and the attenuation of the fluorescence getting from the sample to the
> detector. Depending on the detector type, you'd also need a good
> assessment of the backgrounds. It's probably not impossible, but I think
> it would not be easy unless that was the actual point of the experiment and
> you made many careful measurements of the detection system. If you're
> asking this question here, you'd didn't make those measurements.
>
>
>
> >
> > In case a treatment is needed for the normalized \mu , that would also
> > suit my situation.
> >
> > My idea was to divide by the thickness of the sample but I don't find a
> > reasonable justificiation for this.
> >
>
>
> If you're measuring in fluorescence, dividing by the thickness of the
> sample is not what you want.
>
>
> >
> > I really hope I made the question clear to any reader this time, and if
> > that is not the case I apologyze in advance.
> >
> >
>
> Cheers,
>
> --Matt
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