Talk:Infrared spectroscopy

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The 'Typical Method' section of this article needs an edit to bring it out of the 1970s. The sort of non-FT method that's described isn't used by anyone anymore, and that type of machine hasn't even been available commercially for many years. You would be hard-pressed to find such a machine anywhere, expect perhaps in the back of a university chemistry department's storage closet. In my opinion it should be eliminated entirely, or at least moved to the bottom of the article and placed in some sort of 'history of the technique' section. -July 1, 2005

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It might be helpful to add the equation for IR absorption frequency.

-- I agree. I'm brand new here, how does one add equations? I could write then up in MathType or MathCAD.

--nmathew

To add an equation just use the math tag or click on the button when editing. I'd put that equation in myself but I've but limited myself to editing only after at least 8 hours sleep the night before! Afn 09:27, 2 September 2005 (UTC)

Contents 1 value for carboxylic acid 2 IR spextroscopy on inorganic molecules 3 Sample Prep 4 IR Correlation Table 5 theory

[edit] value for carboxylic acid

The article puts the values for carboxylic acids as: carboxylic acids/derivates saturated carboxylic acids 1710 cm-1 unsat./aromatic carb. acids 1680-1690 cm-1 esters and lactones 1735 cm-1 (influence of conjugation and ring size like with ketones) anhydrides 1760 and 1820 cm-1 (both!) halogenides 1801 cm-1 amides 1650 cm-1 (associated amides) carboxylates (salts) 1550-1610 cm-1 (goes for aminoacid zwitterions as well)

but this site (http://www.chem.ucla.edu/~webspectra/irtable.html) puts it as 2800-300 cm-1

so which is it?

Thank you.

The first values you've quoted were for the C=O adsorption in carboxylic acids. The ones you refer to from the other site seem to be for the O-H adsorption region, although that would be more around 3000-3500cm-1. A carboxylic acid has both groups, but the article has categorised their adsorptions separately, corresponding to the individual bonds, for simplicity. krebbe 15:09, 18 January 2006 (UTC)

[edit] IR spextroscopy on inorganic molecules

Since the article said that IR spectroscopy is also helpful or used in inorganic compounds, it is OK to include the fundamental vibrations of such inorganic compounds in the correlation table and the visual representation as well. --Aeron Valderrama 00:37, 11 July 2006 (UTC)

[edit] Sample Prep

Took out: "These salts do not absorb infrared light, so spectral lines will only appear from the analyte." Mediums such as KBr are used because they do not absorb IR light in the region most organic chemists are concerned with, but they do absorb IR light.

This section also needs a grammar make over so it at least sounds like someone with a degree wrote it.

[edit] IR Correlation Table

The IR correlation table ought to be moved back into this article. The greatest reason is that one cannot find the article unless you look in the history of this article. Searching for "Infrared Specroscopy Correlation table" (the name of the article) doesn't find it at all. And in every book (that I've seen, and I've seen a few) covering IR spectroscopy for those intent on using it, a detailed table can be found.

I just think not including the correlation chart is like talking about a country without including a political map of its borders, it leaves out something of importance.

[edit] theory

I don't want to be nitpicky, but isn't it "antisymmetrical" instead of "asymmetrical" stretching?

Lothar —The preceding unsigned comment was added by 217.224.243.13 (talk) 17:39, 2 February 2007 (UTC).

It's usually asymmetric but 'antisymmetric can also be used. --Kkmurray 16:07, 5 April 2007 (UTC)