Re: [Ifeffit] Origin of terminology "self-absorption"
I tried a few searches, but rapidly get lost in other uses of the term. My guess is we borrowed it from some other spectroscopy, much the way we borrowed "Debye-Waller factor" from XRD, and then proceeded to change its meaning. But it would be nice to be able to track that down. --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory On Nov 16, 2010, at 10:54 AM, Matthew Marcus wrote:
It's definitely a misnomer. I use "overabsorption" and encourage others to do so. I suppose to track it down would require going back over the seminal papers on the subject. mam
On 11/16/2010 10:19 AM, Scott Calvin wrote:
Hi all,
As some of you know, I'm currently working on a textbook on XAFS analysis. Because of that, I'm going to occasionally pose some questions for the list that may seem a bit random. I hope none of you mind me using the list in this way; the questions may seem to come out of left field, but I think they will still be of interest to many.
With that said, here's my question for today:
What is the origin of the use of "self-absorption" to describe the suppression of fine-structure observed in thick, concentrated samples measured in fluorescence? I understand the physics of the effect itself, my question is the curious wording. Compared to a thin concentrated sample, the effect might better be described as "saturation," while compared to a thick dilute sample, it's actually related to a lack of absorption by other elements.
--Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
It's a term taken from x-ray fluorescence spectroscopy, or probably
really any fluorescence spectroscopy, where it has very sensible
meaning: the attenuation of the fluorescence signal by the sample
itself. I would even say it is used "mostly correctly" in XAFS, or at
least with a similar intent as the original term, much as the term
Debye-Waller Factor is used.
--Matt
On Tue, Nov 16, 2010 at 1:01 PM, Scott Calvin
I tried a few searches, but rapidly get lost in other uses of the term. My guess is we borrowed it from some other spectroscopy, much the way we borrowed "Debye-Waller factor" from XRD, and then proceeded to change its meaning. But it would be nice to be able to track that down.
--Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory
On Nov 16, 2010, at 10:54 AM, Matthew Marcus wrote:
It's definitely a misnomer. I use "overabsorption" and encourage others to do so. I suppose to track it down would require going back over the seminal papers on the subject. mam
On 11/16/2010 10:19 AM, Scott Calvin wrote:
Hi all,
As some of you know, I'm currently working on a textbook on XAFS analysis. Because of that, I'm going to occasionally pose some questions for the list that may seem a bit random. I hope none of you mind me using the list in this way; the questions may seem to come out of left field, but I think they will still be of interest to many.
With that said, here's my question for today:
What is the origin of the use of "self-absorption" to describe the suppression of fine-structure observed in thick, concentrated samples measured in fluorescence? I understand the physics of the effect itself, my question is the curious wording. Compared to a thin concentrated sample, the effect might better be described as "saturation," while compared to a thick dilute sample, it's actually related to a lack of absorption by other elements.
--Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
But the effect commonly known by that name not only has nothing to do with the re-absorption of the fluorescent light by the sample,
it can be reduced by increasing
such absorption, for instance by doing grazing-exit detection.
mam
----- Original Message -----
From: "Matt Newville"
I tried a few searches, but rapidly get lost in other uses of the term. My guess is we borrowed it from some other spectroscopy, much the way we borrowed "Debye-Waller factor" from XRD, and then proceeded to change its meaning. But it would be nice to be able to track that down.
--Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory
On Nov 16, 2010, at 10:54 AM, Matthew Marcus wrote:
It's definitely a misnomer. I use "overabsorption" and encourage others to do so. I suppose to track it down would require going back over the seminal papers on the subject. mam
On 11/16/2010 10:19 AM, Scott Calvin wrote:
Hi all,
As some of you know, I'm currently working on a textbook on XAFS analysis. Because of that, I'm going to occasionally pose some questions for the list that may seem a bit random. I hope none of you mind me using the list in this way; the questions may seem to come out of left field, but I think they will still be of interest to many.
With that said, here's my question for today:
What is the origin of the use of "self-absorption" to describe the suppression of fine-structure observed in thick, concentrated samples measured in fluorescence? I understand the physics of the effect itself, my question is the curious wording. Compared to a thin concentrated sample, the effect might better be described as "saturation," while compared to a thick dilute sample, it's actually related to a lack of absorption by other elements.
--Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Scott may be right about its borrowing. The term "self-absorption" is used in XRF and XRD to describe the fall-off in characteristic line emission from an x-ray tube with a heavy element (e.g. silver or tungsten) target as the potential is increased. With light element targets the emission increases roughly monotonically with potential. With heavy element targets, the emission eventually saturates and may even roll-over. See "Quantitative X-ray Spectrometry", Jenkins, Gould and Geddke, 1981. Carl Carl W. Ponader Ph.D. Characterization Science & Services Corning Incorporated SP-AR-2-4 Corning, NY 14831 607-974-3364 -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Scott Calvin Sent: Tuesday, November 16, 2010 2:02 PM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Origin of terminology "self-absorption" I tried a few searches, but rapidly get lost in other uses of the term. My guess is we borrowed it from some other spectroscopy, much the way we borrowed "Debye-Waller factor" from XRD, and then proceeded to change its meaning. But it would be nice to be able to track that down. --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory On Nov 16, 2010, at 10:54 AM, Matthew Marcus wrote:
It's definitely a misnomer. I use "overabsorption" and encourage others to do so. I suppose to track it down would require going back over the seminal papers on the subject. mam
On 11/16/2010 10:19 AM, Scott Calvin wrote:
Hi all,
As some of you know, I'm currently working on a textbook on XAFS analysis. Because of that, I'm going to occasionally pose some questions for the list that may seem a bit random. I hope none of you mind me using the list in this way; the questions may seem to come out of left field, but I think they will still be of interest to many.
With that said, here's my question for today:
What is the origin of the use of "self-absorption" to describe the suppression of fine-structure observed in thick, concentrated samples measured in fluorescence? I understand the physics of the effect itself, my question is the curious wording. Compared to a thin concentrated sample, the effect might better be described as "saturation," while compared to a thick dilute sample, it's actually related to a lack of absorption by other elements.
--Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
participants (4)
-
Matt Newville -
Matthew Marcus -
Ponader, Carl W Dr -
Scott Calvin