[Ifeffit] Ifeffit Digest, Vol 167, Issue 3
Raj kumar
rajrk37 at gmail.com
Thu Jan 5 08:36:25 CST 2017
Hi Scott and Bruce,
In continuation with earlier email, here, I am just briefing the
observation on the analyzing systems. In my case, reference sample (bulk
YbVO4) itself takes large second so2 with huge uncertainty(2.04 +/- 1.36) to
get a satisfactory fit. Further, this parameter is found to correlate with
ss1 and delc (a parameter to define the movement of atoms in c direction).
Among two, the former parameter (ss1) strongly correlate with so2 and take
value below 1 and large so2, for using ss1 as fixed and free parameter,
respectively. This large value of so2 cannot be controlled with the used
model. Also, I have tried to fit the curve with fixed so2 i.e., below 1 but
leads to unsatisfactory fit. After considering your suggestion and closely
look into second so2, i have concluded the following: Since, so2 is used as
a normalization parameter and with the available uncertainty, i would
consider the obtained number as reasonable value to normalize the unknown
to calculate the CN in other systems. Is this good strategy to proceed to
calculate the CN? and later to describe the trend on obtained parameters?
Regards,
Raj
On 4 January 2017 at 12:38, <ifeffit-request at millenia.cars.aps.anl.gov>
wrote:
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> Today's Topics:
>
> 1. Re: Ifeffit Digest, Vol 167, Issue 2 (Raj kumar)
> 2. Re: Ifeffit Digest, Vol 167, Issue 2 (Bruce Ravel)
> 3. Re: Ifeffit Digest, Vol 167, Issue 2 (Raj kumar)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 3 Jan 2017 21:32:51 +0100
> From: Raj kumar <rajrk37 at gmail.com>
> To: ifeffit at millenia.cars.aps.anl.gov
> Subject: Re: [Ifeffit] Ifeffit Digest, Vol 167, Issue 2
> Message-ID:
> <CACc-a9+uy+4i65LrZf8kiJRk6bdTD2cVSdeeGLp2r0x4fDBrSQ at mail.
> gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Scott,
>
> Thank you very much for your prompt response. EXAFS measurement was done
> after the XRD characterization. From XRD, it is confirmed that there is no
> side phase formation and contamination. Hence, i guess the heavier element
> role could be avoided here.
>
> Split distances could be the reason??. The following is the method, i have
> opted for modelling the obtained curve. Since YbVO4 is zircon structure, i
> have constrained distance in paths 3, 8 and 9 with the pre-structural info
> and let other distances vary with regular mathematical expression
> alpha*Reff. am i doing wrong here? Before this, I have tried alpha*Reff for
> all paths but fit failed miserably for multi-shells.
>
> Regards,
> Raj
>
> On 3 January 2017 at 19:00, <ifeffit-request at millenia.cars.aps.anl.gov>
> wrote:
>
> > Send Ifeffit mailing list submissions to
> > ifeffit at millenia.cars.aps.anl.gov
> >
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> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> > or, via email, send a message with subject or body 'help' to
> > ifeffit-request at millenia.cars.aps.anl.gov
> >
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> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of Ifeffit digest..."
> >
> >
> > Today's Topics:
> >
> > 1. Re: Problem with large so2 (Scott Calvin)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Tue, 3 Jan 2017 09:59:18 -0600
> > From: Scott Calvin <dr.scott.calvin at gmail.com>
> > To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> > Subject: Re: [Ifeffit] Problem with large so2
> > Message-ID: <3EF5E209-7681-49C6-9713-4BBF34C619A5 at gmail.edu>
> > Content-Type: text/plain; charset="utf-8"
> >
> > Hi Raj,
> >
> > I haven?t looked at your files, but the kinds of results you are
> > describing often indicate the model you are using beyond the first shell
> is
> > incorrect. It may be that it has the wrong elements (e.g., heavier
> elements
> > are present than what you modelled) or that the model includes split
> > distances when in reality the compound is more symmetric.
> >
> > In short, no, the high second S02 does not make sense (although it would
> > be good to know the uncertainties).
> >
> > Best,
> > Scott Calvin
> > Lehman College of the City University of New York
> >
> > > On Jan 3, 2017, at 9:38 AM, Raj kumar <rajrk37 at gmail.com> wrote:
> > >
> > > Dear All,
> > >
> > >
> > >
> > > I have been trying to fit EXAFS signal of YbVO4 both in bulk and
> > nanoparticles form. Here, I would like to estimate so2 from bulk
> > (reference) and subsequently use the number, as normalization parameter,
> to
> > calculate the co-ordination number in all nanoparticles. Nanoparticles
> were
> > synthesized by solution route. From our earlier understanding on the
> > synthesis, in some cases, Yb may or may not completely involve in
> reaction.
> > Therefore, I except Yb in two environments, one surrounded by mere oxygen
> > (in precise oxygen-Hydrogen; due to disorder one may expect a single
> peak)
> > and another one in YbVO4 environment. With this info and for reasonable
> > fit, I have used two so2 as free parameters for N: one for first shell
> > (oxygen at two distances) and another for rest other shells. If I use
> > single so2, I obtain the value of around 0.92 with unsatisfactory fit
> > whereas the fit seems plausible with two so2 i.e., 0.75 and 2.2,
> > respectively. Using the same strategy, I could successfully fi!
> > t the nanoparticles again with large second so2 (1.79). From literature
> > and IFEFFIT earlier discussion, i understood that so2 should be between
> > 0.8-1.2 value. Here, I would like to know, does this huge second so2
> value
> > makes sense? is the obtained so2 value can be used to calculated
> > coordination number for unknown? Further, i have attached my worked files
> > with this message.
> > >
> > >
> > >
> > > Regards,
> > >
> > > Raj
> > >
> > > <YbVO4-bulk.fpj><YbVO4-nps.fpj>_____________________________
> > __________________
> > > Ifeffit mailing list
> > > Ifeffit at millenia.cars.aps.anl.gov
> > > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
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> > _______________________________________________
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> > End of Ifeffit Digest, Vol 167, Issue 2
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>
> Message: 2
> Date: Tue, 3 Jan 2017 15:45:37 -0500
> From: Bruce Ravel <bravel at bnl.gov>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] Ifeffit Digest, Vol 167, Issue 2
> Message-ID: <d24675d6-264a-7850-54bd-109fe393b9bd at bnl.gov>
> Content-Type: text/plain; charset=windows-1252; format=flowed
>
> On 01/03/2017 03:32 PM, Raj kumar wrote:
> > From XRD, it is confirmed that there is no side phase formation and
> > contamination. Hence, i guess the heavier element role could be avoided
> > here.
>
> Raj,
>
> While this might be true for your sample, in general, a statement like
> this always concerns me.
>
> From XRD, you can say is that there is no /crystalline/ side phase
> formation and that there is no contamination in the /diffracting/
> /portion/ of the sample.
>
> It is very common when preparing nanoparticulate matter for there to be
> non- or poorly-diffracting content in the sample. If that content
> contains the absorbing element, then it will have an impact on the XAS
> data.
>
> B
>
>
>
> --
> Bruce Ravel ------------------------------------ bravel at bnl.gov
>
> National Institute of Standards and Technology
> Synchrotron Science Group at NSLS-II
> Building 743, Room 114
> Upton NY, 11973
>
> Homepage: http://bruceravel.github.io/home/
> Software: https://github.com/bruceravel
> Demeter: http://bruceravel.github.io/demeter/
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 4 Jan 2017 12:38:05 +0100
> From: Raj kumar <rajrk37 at gmail.com>
> To: ifeffit at millenia.cars.aps.anl.gov
> Subject: Re: [Ifeffit] Ifeffit Digest, Vol 167, Issue 2
> Message-ID:
> <CACc-a9+EHP7bGjjpxW+cUp=9LzSZzKG=TvnM+gYVeR-T2g1yqQ at mail.
> gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Scott,
>
> I would like to add an extra point to the previous message. Yes, i am
> getting a large uncertainty for the second so2 (2.04 +/- 1.36).
>
> Regards,
> Raj
>
> On 3 January 2017 at 21:32, Raj kumar <rajrk37 at gmail.com> wrote:
>
> > Hi Scott,
> >
> > Thank you very much for your prompt response. EXAFS measurement was done
> > after the XRD characterization. From XRD, it is confirmed that there is
> no
> > side phase formation and contamination. Hence, i guess the heavier
> element
> > role could be avoided here.
> >
> > Split distances could be the reason??. The following is the method, i
> have
> > opted for modelling the obtained curve. Since YbVO4 is zircon structure,
> i
> > have constrained distance in paths 3, 8 and 9 with the pre-structural
> info
> > and let other distances vary with regular mathematical expression
> > alpha*Reff. am i doing wrong here? Before this, I have tried alpha*Reff
> for
> > all paths but fit failed miserably for multi-shells.
> >
> > Regards,
> > Raj
> >
> > On 3 January 2017 at 19:00, <ifeffit-request at millenia.cars.aps.anl.gov>
> > wrote:
> >
> >> Send Ifeffit mailing list submissions to
> >> ifeffit at millenia.cars.aps.anl.gov
> >>
> >> To subscribe or unsubscribe via the World Wide Web, visit
> >> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >> or, via email, send a message with subject or body 'help' to
> >> ifeffit-request at millenia.cars.aps.anl.gov
> >>
> >> You can reach the person managing the list at
> >> ifeffit-owner at millenia.cars.aps.anl.gov
> >>
> >> When replying, please edit your Subject line so it is more specific
> >> than "Re: Contents of Ifeffit digest..."
> >>
> >>
> >> Today's Topics:
> >>
> >> 1. Re: Problem with large so2 (Scott Calvin)
> >>
> >>
> >> ----------------------------------------------------------------------
> >>
> >> Message: 1
> >> Date: Tue, 3 Jan 2017 09:59:18 -0600
> >> From: Scott Calvin <dr.scott.calvin at gmail.com>
> >> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> >> Subject: Re: [Ifeffit] Problem with large so2
> >> Message-ID: <3EF5E209-7681-49C6-9713-4BBF34C619A5 at gmail.edu>
> >> Content-Type: text/plain; charset="utf-8"
> >>
> >> Hi Raj,
> >>
> >> I haven?t looked at your files, but the kinds of results you are
> >> describing often indicate the model you are using beyond the first
> shell is
> >> incorrect. It may be that it has the wrong elements (e.g., heavier
> elements
> >> are present than what you modelled) or that the model includes split
> >> distances when in reality the compound is more symmetric.
> >>
> >> In short, no, the high second S02 does not make sense (although it would
> >> be good to know the uncertainties).
> >>
> >> Best,
> >> Scott Calvin
> >> Lehman College of the City University of New York
> >>
> >> > On Jan 3, 2017, at 9:38 AM, Raj kumar <rajrk37 at gmail.com> wrote:
> >> >
> >> > Dear All,
> >> >
> >> >
> >> >
> >> > I have been trying to fit EXAFS signal of YbVO4 both in bulk and
> >> nanoparticles form. Here, I would like to estimate so2 from bulk
> >> (reference) and subsequently use the number, as normalization
> parameter, to
> >> calculate the co-ordination number in all nanoparticles. Nanoparticles
> were
> >> synthesized by solution route. From our earlier understanding on the
> >> synthesis, in some cases, Yb may or may not completely involve in
> reaction.
> >> Therefore, I except Yb in two environments, one surrounded by mere
> oxygen
> >> (in precise oxygen-Hydrogen; due to disorder one may expect a single
> peak)
> >> and another one in YbVO4 environment. With this info and for reasonable
> >> fit, I have used two so2 as free parameters for N: one for first shell
> >> (oxygen at two distances) and another for rest other shells. If I use
> >> single so2, I obtain the value of around 0.92 with unsatisfactory fit
> >> whereas the fit seems plausible with two so2 i.e., 0.75 and 2.2,
> >> respectively. Using the same strategy, I could successfully fi!
> >> t the nanoparticles again with large second so2 (1.79). From literature
> >> and IFEFFIT earlier discussion, i understood that so2 should be between
> >> 0.8-1.2 value. Here, I would like to know, does this huge second so2
> value
> >> makes sense? is the obtained so2 value can be used to calculated
> >> coordination number for unknown? Further, i have attached my worked
> files
> >> with this message.
> >> >
> >> >
> >> >
> >> > Regards,
> >> >
> >> > Raj
> >> >
> >> > <YbVO4-bulk.fpj><YbVO4-nps.fpj>_____________________________
> >> __________________
> >> > Ifeffit mailing list
> >> > Ifeffit at millenia.cars.aps.anl.gov
> >> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >> > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
> >>
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> >> ------------------------------
> >>
> >> Subject: Digest Footer
> >>
> >> _______________________________________________
> >> Ifeffit mailing list
> >> Ifeffit at millenia.cars.aps.anl.gov
> >> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >> Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
> >>
> >>
> >> ------------------------------
> >>
> >> End of Ifeffit Digest, Vol 167, Issue 2
> >> ***************************************
> >>
> >
> >
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