[Ifeffit] Some basic questions

[pushkar shejwalkar]

Hi Alexey,
    Thank you very much for your kind advise and help. I will certainly
look into Linear combination to determine Pd and Pd2+. I saw the similar
information in terms of the Au and Au3+ data is available on gitHub. Hope
that it will be helpful in designing the experiment in my case.
Best
Pushkar

On Wed, Feb 1, 2017 at 8:08 PM, Alexey Boubnov <alexeyboubnov at gmail.com>
wrote:

> Dear Pushkar,
>
> 1) The priority is the mass, i.e. the number of absorbing atoms of the
> measured element, because that determines the edge jump. The thickness
> mostly depends on the type of sample and amount of BN (or cellulose) used
> and is usually important for the stability and homogeneity of the pellet.
> 0.5 mm to 1 mm thickness is fine. The thickness affects the total
> absorption, so do not use too much BN. If your pure material makes good
> pellets without BN, great!
>
> 2) You have a bimetallic Cu-Pd alloy. Yes, treat Pd as a neighbour of Cu.
> In the feff-input, replace some of the Cu with Pd and calculate the
> scattering paths. For the Cu K-edge spectrum, refine the Cu-Cu and Cu-Pd
> paths and for the Pd K-edge spectrum refine the Pd-Pd and Pd-Cu paths.
> Prior to that, refine the spectra of the pure metals (Cu and Pd foils) to
> get an idea of the S02, deltaE0 and sigma2 values that you should expect
> for the alloy.
> Googling "exafs bimetallic" gives many nice articles.
>
> 3) Using linear combination analysis (e.g. in Athena) the fraction of Pd
> and Pd2+ can be easily determined.
>
> All the best!
> Alexey
>
> 2017-02-01 7:19 GMT+01:00 pushkar shejwalkar <pshejwalkar2004 at gmail.com>:
>
>> Dear All,
>>         I have some basic questions that are more related to the
>> practical handling of the samples rather than the concept.
>> 1) Recently we had to prepare for the Cu and Pd samples and I had carried
>> out the calculations of how much material will be needed for such
>> measurement to get relatively good uT and deltauT values. For such purpose,
>> I used the program developed by SPring-8 (on their website) dedicated for
>> BL-14 beamline. In this program we can put in the cell diameter and what
>> kind of BN thickness is needed. Since my samples are metal immobilized
>> heterogeneous organic materials, it has a lot of background in terms of
>> C,H,Si,N etc. Thus, I use material directly and I do not use BN at all. So
>> my BN thickness is 0. How do I change this mass of material needed into the
>> thickness of cell? What I do, is I use density of material and for the
>> cylinder of pellet I calculate the thickness. My question is, WHAT GETS THE
>> PRIORITY, THICKNESS OR MASS of material that goes in? Becuase thickness of
>> pellet governs the XAFS equation, whereas mass governs the absorption peak
>> (height and high uT). It is difficult to comprehend everything written on
>> website, Since the website is in Japanese and I am not. Also it is kinda
>> difficult to communicate with the authorities directly in free English, I
>> am asking this question here.
>> 2) Secondly, In the mixed metal case of type AB, If I focus the energy
>> for A, how will the B have effect on the scattering of A. A=Cu and B=Pd. I
>> will be measuring Pd in later days. Would it be possible to consider Pd (in
>> this case) as a neighboring atom and purely treat it like I would otherwise
>> e.g. N or O like that?
>> Since this is my first time with mixed metal situation, any reference
>> publications or material to read would be very helpful.
>> 3) In another case of mine, I have Pd and Pd2+ mixture in my sample.
>> Would it be possible to estimate the exact concentration of each of them?
>> Using two analytically pure Pd and Pd2+ salts to make calibration curve
>> would it be possible to get the exact concentration? What will be the
>> independent variable on the graph?
>> .
>> Thank you for your kind help and information, in advance
>> Best
>> Pushkar
>>
>> --
>> Best Regards,
>> Pushkar Shejwalkar.
>> Post-doctoral -Researcher,
>> Tokyo Engineering University,
>> Tokyo-to
>> Japan
>>
>>
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>
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-- 
Best Regards,
Pushkar Shejwalkar.
Post-doctoral -Researcher,
Tokyo Engineering University,
Tokyo-to
Japan
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