Hi Juan,
Without getting too much into detail, the trick
is to introduce constraints that seem physically
reasonable and see what happens. This requires
you to use the "a priori" information you have
about your system; i.e. the information you have
from non-EXAFS theory or experiment.
Mayb
Hi all,
Thank you very much Scott for your not slow answer and sorry for my very slow
one.
I think my system is a little bit complicated. I have bimetallic catalysts
(PtSn)
and I did fits supposing two different structures but I do not know the relative
proportion of these two structures. In th
Hi Juan,
Sorry for the slow response; the end of the term gets busy for me!
I think there are still some loose ends in this
discussion that are worth trying to tie up:
At 03:03 PM 12/11/2006, you wrote:
First of all, I would like to thanks Anatoly for his file and everybody for
useful comm
using Ifeffit
Subject: Re: [Ifeffit] CN and bond distances in Artemis
Hi Anatoly,
Sorry very much Anatoly, you are right, I only told you low values for S02
but I
did not give any value to you. Which is the minimum reasonable coordiantion
number
in a fcc structure?
Yes, I assumed a fixed value of
Hi Anatoly,
Sorry very much Anatoly, you are right, I only told you low values for S02 but I
did not give any value to you. Which is the minimum reasonable coordiantion
number
in a fcc structure?
Yes, I assumed a fixed value of 12 for N and I left S02 as variable. I realize
that my fault was to
Antonio Macia Agullo
Sent: Tuesday, December 12, 2006 12:25 PM
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] CN and bond distances in Artemis
Hi Matt,
Thank you very much for your comments. S02 is a variable for me and it gives
information about the size of the particles (related to
Hi Matt,
Thank you very much for your comments. S02 is a variable for me and it gives
information about the size of the particles (related to coordination number).
For
instance, in the case of Pt foil it should be close to 0.85, however it is much
smaller (0.20) in the case of platinum nanoparti
Juan:
For S02 from fluorescence measurements or data collected at other
times/beamlines, etc,
I would ask what purpose this S02 is serving in your analysis. I'd
guess that you do "the normal thing" of fixing this value for several
paths and then float the coordination numbers so that
amp = S
Hi all,
First of all, I would like to thanks Anatoly for his file and everybody for
useful comments. I have analysed Anatoly's data and I have obtained a good value
for S02 = 0.85 or 0.82 (depending on the number of variables used). So, my data
is the problem, and it is not my analysis, but maybe
On Tuesday 05 December 2006 13:02, Scott Calvin wrote:
> P.S. Just as I finished writing this, Matthew
> Marcus' post came through. I do have Pt foil data
> in transmission that I can dig up for you, if
> you'd like. Maybe I'll send it to Matt to put in
> the database; it's pretty good quality, as
but why to take chances?
Anatoly
-Original Message-
From: Matthew Marcus [mailto:[EMAIL PROTECTED]
Sent: Tuesday, December 05, 2006 1:54 PM
To: [EMAIL PROTECTED]; XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] CN and bond distances in Artemis
I imagine somebody has done so and woul
Hi JA,
I agree with Anatoly that remeasuring in
transmission is a good idea, if you have the beam
time. But I would also note that the value you
have for S02 with the correction is within the
realm of possibility, considering the
uncertainty: 1.20 - 0.30 = 0.90. And part of the
reason for s
x27;s
not essential.
mam
- Original Message -
From: "Anatoly Frenkel" <[EMAIL PROTECTED]>
To: "XAFS Analysis using Ifeffit"
Sent: Tuesday, December 05, 2006 10:37 AM
Subject: RE: [Ifeffit] CN and bond distances in Artemis
I would remeasure Pt foil in transmi
I would remeasure Pt foil in transmission, by all means.
Anatoly
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Juan
Antonio Macia Agullo
Sent: Tuesday, December 05, 2006 1:32 PM
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] CN and bond
Hi all,
I did fits with self absorption corrected data (Fluo and Booth algorithms) and
the
value for S02 is 1.20 (0.30). It seems that I am not very lucky, if I take an
average value (1.20 and 0.50), it should be ok (0.85) jeje, I am joking.
Then...what can I do now?
Thank you very much,
Best
On Tue, 5 Dec 2006, Juan Antonio Maciá Agulló wrote:
Ok, how can I apply an "infinite" sample correction? The other samples are
measured also in fluorescence mode, then is it better to measure Ptfoil in the
same conditions (fluorescence)?
The question about applying the correction has been
Juan,
There are 2 ways to apply the self-absorption correction in Athena. The
first way is to pick thicknesses starting with a couple microns and
going thicker and thicker until the correction has no effect. I like
this method because it gives an idea of the effects that thickness and
conce
Ok, how can I apply an "infinite" sample correction? The other samples are
measured also in fluorescence mode, then is it better to measure Ptfoil in the
same conditions (fluorescence)?
Thanks a lot
Best regards,
JA
begin:vcard
n:Maciá Agulló;Juan Antonio
tel;fax:0034-965903454
tel;work:0034-
On Tuesday 05 December 2006 09:03, Carlo Segre wrote:
> It looks like this is fluorescence data. It is likely that you have
> significant self-absorption if this is a Pt foil. Try to apply an
> "infinite" sample correction to this data before fitting. That should
> correct the SO2 somewhat.
I
Hi Juan Antonio:
It looks like this is fluorescence data. It is likely that you have
significant self-absorption if this is a Pt foil. Try to apply an
"infinite" sample correction to this data before fitting. That should
correct the SO2 somewhat. A much better thing to do is to take this
Hi all,
I did a multiple shell fit for platinum foil and the results were similar: S02 =
0.51 and the uncertainty varies from 0.02 to 0.03 depending on the fit. Please
find enclosed a file with values of energy, I0 and I of the platinum foil. I
include this file if someone has curiosity on raw da
Did you check your data against someone else's? Maybe you have hole effect
or overabsorption.
mam
- Original Message -
From: "Scott Calvin" <[EMAIL PROTECTED]>
To: "XAFS Analysis using Ifeffit"
Sent: Monday, December 04, 2006 11:42 AM
Subject: Re: [If
Hi Juan,
You're saying you have that low a value of S02
for a bulk platinum standard? Anatoly's
right...you'd better figure out why before you
continue. But one piece of advice I have: for a
simple crystalline standard like platinum, by all
means fit more than one coordination shell (with
c
If you mean that your S02 value for platinum foil is 0.53 instead of the
expected 0.85 or so, you have to first find out why that happened. There are
too many (for a quick list) setup-related and sample-related reasons that
can explain why it happened. You should be careful with your NP data
analys
24 matches
Mail list logo
