ANALYTICAL CHEMISTRY - INFRARED SPECTROSCOPY Commonly referred to as IR spectroscopy, this technique allows chemists to identify characteristic groups of atoms (functional groups) present in molecules.

C H C H C C THE FINGERPRINT REGION - 1500CM-1 TO 500CM-1 Stretch Stretch Stretch The fingerprint region of the spectrum contains a complex set of absorptions, which are unique to each compound. Though these are M M M hard to interpret visually, by comparison with references they allow identification of specific compounds. ALKENE ALDEHYDE ALKENE AROMATICS

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ALKYNE ALKANE ALKYNE CARBONYLS AROMATICS ESTERS, ETHERS, ALCOHOLS, ALKYL CHLORIDE (850-550) CARBOXYLIC ACIDS ALKYL BROMIDE (690-515)

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Infrared frequencies make up a portion of the electromagnetic spectrum. If a range of infrared frequencies are shone through an organic compound, some of the frequencies are absorbed by the chemical bonds within the compound. ierent chemical bonds absorb dierent frequencies of infrared radiation. There are a number of characteristic absorptions which allow functional groups the parts of a compound which give it its particular reactivity to be identified. This graphic shows a number of these absorptions.

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