[Ifeffit] Nickel Chloride XAS data at RT and 320C

Gill, Simerjeet gills at bnl.gov
Tue Jan 15 13:44:29 CST 2019


Hi,

I am working with a molten salt system with Nickel Chloride as one of the components. If you have measured XAS data on anhydrous and hydrated Nickel Chloride at RT and 320C, I would really appreciate if you could share the raw data with me.

Thanks in advance for your help!

Simer

Simerjeet K Gill,
Materials Scientist,
Nuclear Science and Technology Department,
Brookhaven National Lab,
Upton, NY 11973

-----Original Message-----
From: Ifeffit <ifeffit-bounces at millenia.cars.aps.anl.gov> On Behalf Of ifeffit-request at millenia.cars.aps.anl.gov
Sent: Friday, January 11, 2019 12:20 PM
To: ifeffit at millenia.cars.aps.anl.gov
Subject: Ifeffit Digest, Vol 191, Issue 7

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: Standard deviation of R value (Matt Newville)
   2. Re: Standard deviation of R value (Anatoly Frenkel)
   3. Re: Standard deviation of R value (Erin Finley)


----------------------------------------------------------------------

Message: 1
Date: Fri, 11 Jan 2019 10:04:49 -0600
From: Matt Newville <newville at cars.uchicago.edu>
To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
Subject: Re: [Ifeffit] Standard deviation of R value
Message-ID:
	<CA+7ESbo=kOiHZx9skxwv6qzHADH9q5Rh2u=Y8np+5AB-XqRyiA at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Hi Erin,

On Fri, Jan 11, 2019 at 8:19 AM Erin Finley <efinley9033 at gmail.com> wrote:

> Hello, I see in many publications the R value reported with a standard 
> deviation. However, when I look at my resulting data from a fit I 
> don't see one listed. I am still new to EXAFS research and so I am 
> wondering where I can get this information. I am assuming I need to 
> calculate it from another parameter I am just not sure which one.
>
>
The uncertainties in R are typically in the fit report.  But also, we typically refine a "delR" parameter that is R - Reff, where Reff is the distance (half path-lengh) for the scattering path.  So, if you don't see an uncertainty reported for R but do see an uncertainty for delR (or whatever parameter name you used), use that.  The uncertainty in R will
(normally) be the uncertainty in delR.

If I'm misunderstanding the question, pleas give more details about what you are doing.

--Matt






Thanks for your help!
> Cheers,
>
> --
> Erin Finley
> PhD Candidate
> Brgoch Research Group
> Department of Chemistry
> University of Houston
> _______________________________________________
> 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
>


--
--Matt Newville <newville at cars.uchicago.edu> 630-252-0431
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20190111/c74ffe28/attachment-0001.html>

------------------------------

Message: 2
Date: Fri, 11 Jan 2019 11:18:03 -0500
From: Anatoly Frenkel <anatoly.frenkel at stonybrook.edu>
To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
Subject: Re: [Ifeffit] Standard deviation of R value
Message-ID:
	<CAFsMoZanre1HbNA9oXgNi9-EeJAt5XCABg6JbOvgMPq-_O9x1A at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

As an additional comment, it is a murky issue whether the reported thing together with R is the standard deviation. It is not easy to find it in the literature but there are some papers dating back to the 1990s that state that the uncertainties reported in the EXAFS fitting results correspond to the 95% confidence level which means 2 standard deviations for an approximately normal data set. I don't think it is correct. Regardless whether the distribution of some or all fitting variables are treated by the Levenburg-Marquartd method as normal or not, the reported error is really not a standard deviation but a square root of the element in a covariance matrix. What is the relationship of that and the standard deviation of the fitting variable is one of the few remaining unsolved mysteries in EXAFS analysis.

Anatoly


On Fri, Jan 11, 2019 at 11:05 AM Matt Newville <newville at cars.uchicago.edu>
wrote:

> Hi Erin,
>
> On Fri, Jan 11, 2019 at 8:19 AM Erin Finley <efinley9033 at gmail.com> wrote:
>
>> Hello, I see in many publications the R value reported with a 
>> standard deviation. However, when I look at my resulting data from a 
>> fit I don't see one listed. I am still new to EXAFS research and so I 
>> am wondering where I can get this information. I am assuming I need 
>> to calculate it from another parameter I am just not sure which one.
>>
>>
> The uncertainties in R are typically in the fit report.  But also, we 
> typically refine a "delR" parameter that is R - Reff, where Reff is 
> the distance (half path-lengh) for the scattering path.  So, if you 
> don't see an uncertainty reported for R but do see an uncertainty for 
> delR (or whatever parameter name you used), use that.  The uncertainty 
> in R will
> (normally) be the uncertainty in delR.
>
> If I'm misunderstanding the question, pleas give more details about 
> what you are doing.
>
> --Matt
>
>
>
>
>
>
> Thanks for your help!
>> Cheers,
>>
>> --
>> Erin Finley
>> PhD Candidate
>> Brgoch Research Group
>> Department of Chemistry
>> University of Houston
>> _______________________________________________
>> 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
>>
>
>
> --
> --Matt Newville <newville at cars.uchicago.edu> 630-252-0431 
> _______________________________________________
> 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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20190111/77e833a3/attachment-0001.html>

------------------------------

Message: 3
Date: Fri, 11 Jan 2019 10:22:41 -0600
From: Erin Finley <efinley9033 at icloud.com>
To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
Subject: Re: [Ifeffit] Standard deviation of R value
Message-ID: <14556591-AA95-4EBB-B264-FC6BF138632C at icloud.com>
Content-Type: text/plain; charset="us-ascii"

Thanks Matt! That makes perfect sense and what I had thought may be the case. 

Erin  

> On Jan 11, 2019, at 10:04 AM, Matt Newville <newville at cars.uchicago.edu> wrote:
> 
> Hi Erin,
> 
>> On Fri, Jan 11, 2019 at 8:19 AM Erin Finley <efinley9033 at gmail.com> wrote:
>> Hello, I see in many publications the R value reported with a standard deviation. However, when I look at my resulting data from a fit I don't see one listed. I am still new to EXAFS research and so I am wondering where I can get this information. I am assuming I need to calculate it from another parameter I am just not sure which one.
>> 
> 
> The uncertainties in R are typically in the fit report.  But also, we typically refine a "delR" parameter that is R - Reff, where Reff is the distance (half path-lengh) for the scattering path.  So, if you don't see an uncertainty reported for R but do see an uncertainty for delR (or whatever parameter name you used), use that.  The uncertainty in R will (normally) be the uncertainty in delR.
> 
> If I'm misunderstanding the question, pleas give more details about what you are doing.
> 
> --Matt
> 
> 
> 
> 
> 
> 
>> Thanks for your help!
>> Cheers,
>> 
>> --
>> Erin Finley
>> PhD Candidate
>> Brgoch Research Group
>> Department of Chemistry
>> University of Houston
>> _______________________________________________
>> 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
> 
> 
> --
> --Matt Newville <newville at cars.uchicago.edu> 630-252-0431 
> _______________________________________________
> 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20190111/5a915598/attachment.html>

------------------------------

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 191, Issue 7
***************************************



More information about the Ifeffit mailing list