Talk:Circular dichroism

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Q: Can anyone tell me if CD spectroscopy has been tested on polymers, and not only on biological materials ? thank you. Guillom 13:59, 4 October 2005 (UTC)

A: Yes you can, provided the polymers you are performing the measurements on are not racemized during the polymerization reaction. Racemization can, for example, occur in concentrated NaOH solutions at high temperatures.

I think the link to ellipticity that is redirected to the flattening article should be removed because this parameter is different than the definition of elliptical polarization. --Bjsamelsonjones 6/28/06

Q: In the 'Experimental limitations' is this 0.1 mm pathlength correct? Or should it be 1 mm? Thanks A: It is correct. Both 1mm and 0.1 mm cuvettes are used. 0.1 mm cuvettes reduce the light scattering, leading to better spectra.

Cells are available with path lengths to .05mm (one cell manufacturer) , and shorter paths may sometimes be used; there are practical difficulties, e.g. knowing the true path length, sealing the mating faces so that evaporation does not change the concentration. Non-demountnable cells also exist. They can be very difficult to clean, and are quite expensive. Not only is high-purity syntheic quartz needed, but the cells should be strain-free, and the faces should be parallel. The benefit of short paths is more related to lower solvent absorbtion, as mentioned in the article, than to scattering. It is a challenge to find an appropriate solvent for work below 200nm. Curtis Johnson would be one name to search for in the literarture to learn about appropriate techniques.

--AJim 04:40, 25 March 2007 (UTC)

The article currently reads: "The ultraviolet CD spectrum of proteins can predict important characteristics..." This is misleading. The CD spectrum does not *predict* anything, rather it is a result of the secondary structure present in the protein. --128.227.142.130 21:01, 28 June 2007 (UTC)

[edit] CD Spectrometer

How does the CD spectrometer actually operate? What are the components that actually generate, process, and detect the light? It would be great if there was a schematic that explains how measurements are made. M stone 14:37, 2 November 2007 (UTC)

I agree. An animation has been added but it doesn't explain much. LostLucidity (talk) 16:38, 12 March 2008 (UTC)

[edit] Inaccurate summary / article title: move, rewrite, merge?

While some of the article is about circular dichroism, the article summary inaccurately states "Circular dichroism [...] is a form of spectroscopy". No, circular dichroism spectroscopy is a form of spectroscopy, employing circular dichroism. Circular dichroism is an optical effect, in which a material absorbs light of one circular polarization differently from the other. Given that basically the whole article is "applied" (even the more theoretical first section is mostly about samples and experiments and quantities), I'd suggest that someone a bit more knowledgeable on the subject than I might do something like this:

1. Move this article to a new Circular dichroism spectroscopy article, excising theoretical stuff and replacing it with links here and to Dichroism.
2. Rewrite the existing theoretical/optical content into a new Circular dichroism, probably a stub or start-class article.
3. Evaluate merging Circular dichroism into dichroism.
4. Evaluate whether Circular dichroism spectroscopy needs to live.

Of course, if there's strong consensus on the third or fourth points, they may override the need to go through with the first or the second.

Andrew Rodland (talk) 21:10, 31 December 2007 (UTC)