Talk:Molar absorption coefficient

Absorbance versus absorption
"It is an intrinsic property of the species; the actual absorbance of a sample is dependent on its thickness L and the concentration c of the species."

Should this actually say:?

"It is an intrinsic property of the species; the actual absorption of a sample is dependent on its thickness L and the concentration c of the species."


 * No, absorbance is fine, because it is a way to quantify absorption, and because the phrase refers to the distinct nature of absorbance and molar absorptivity, two different concepts that are often confused.--Nevermore78 01:29, 3 April 2006 (UTC)


 * Note that absorbance has a very specific technical definition. 128.146.32.223 (talk) 02:56, 2 September 2009 (UTC)

Thickness?
I've actually never used the term thickness before, should we perhaps use path length instead of thickness? Hmm. Article needs some work. Better put it on my to-do list.GreatMizuti 13:00, 3 October 2006 (UTC)

Done 84.92.241.186 14:15, 28 April 2007 (UTC)

Units?
Perhaps the units should also be listed on the main page, as is done with all other physics items listed in wiki? Mueschke

I made a separate paragraph for units neffk (talk) 14:10, 28 May 2009 (UTC)

Molar (decadic) absorption coefficient
IUPAC recommends that &epsilon; be called the molar (decadic) absorption coefficient. See, , and especially. — DIV (128.250.204.118 08:20, 7 September 2007 (UTC))


 * This article should be appropriately changed. 128.146.32.223 (talk) 02:56, 2 September 2009 (UTC)


 * These links should be changed, the new IUPAC site don't have it. The new (old) links are: 10.2.1.3 Molecular spectroscopy, 10.3.5.2 Measuring techniques, and 11.2 Terms and symbols used in photochemistry and in light scattering. 148.234.94.14 (talk) 19:48, 10 March 2017 (UTC)

Convert between ε and E1%
Shouldn't ε and E1% be swapped in the conversion formula? It should rather be E1%=(ε*molecular weight)/10 and not vice versa. Sachoques (talk) 20:24, 4 June 2008 (UTC)


 * No, because the units don't work out that way. ε is in M-1cm-1, E1% in g-1 L cm-1, and molecular weight in g mol-1: (mol/L)-1cm-1  =  mol-1 L cm-1 = g-1 L cm-1 * g mol-1 -- 99.153.134.31 (talk) 23:03, 14 September 2008 (UTC)
 * Err... actually, after thinking about it, I'm not sure what units E1% should have (absorbances should be unitless). The general principle holds, though. Since ε is per molar, you need to get the moles in the denominator of the other side. -- 99.153.134.31 (talk) 23:27, 14 September 2008 (UTC)

E1% is unitless, is the absorbance of a solution of 1% protein, with optical path of 1 cm, I believe... — Preceding unsigned comment added by 200.16.16.13 (talk) 19:33, 26 September 2014 (UTC)

So, the conversion is as follows: E1%= 10g mol MW-1 L -1 ε b

Or, the other way around:

ε=E1% MW L mol-1 b-1 g-1 /10 — Preceding unsigned comment added by 200.16.16.13 (talk) 19:39, 26 September 2014 (UTC)

Request for clarification
What is it commonly known by and what is it actually known as, as the lead is somewhat ambiguous. Per WP:COMMONNAME, the article should be located at the article title it is most commonly known. WP:CHEMNAME covers elements and compounds and not other chemistry related articles, thus this article is not covered by that naming convention. —  James ( Talk •  Contribs ) • 6:48pm • 08:48, 8 November 2011 (UTC)

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Swap article title to Extinction coefficient?
I have recorded or examined spectra for several decades, but I have never encountered the term "attenuation coefficient". Never even seen the term before just a few seconds ago in my attempt to learn about extinction coefficients for IR bands. I started a discussion on moving the title to something that practitioners actually use vs what IUPAC thinks we should use. See Wikipedia talk:WikiProject Chemistry.--Smokefoot (talk) 21:46, 28 November 2022 (UTC)
 * There is a pending proposal to move this to Molar absorption coefficient at the discussion linked above. Mdewman6 (talk) 20:21, 1 December 2022 (UTC)