Ir peak table

An infrared peak table lists approximate absorption regions associated with molecular vibrations. It helps generate structural possibilities, but a peak position alone rarely identifies a whole molecule. Use the spectrum, sample context, and other evidence together.

Meaning and context

Common introductory guides place many O–H stretches broadly around 3200–3600 cm⁻¹ and many carbonyl stretches in the general 1650–1800 cm⁻¹ region. These are approximate regions, not fixed positions for every compound or measurement.

Examples and usage

Look at the band’s shape, intensity, and surrounding features as well as its position. A broad band and a sharp band in a similar region may suggest different explanations. Missing expected features can also be informative.

What to check

Hydrogen bonding, conjugation, functional-group environment, and experimental conditions can shift absorptions. Reference tables vary in scope. Treat a table as a guide to interpretation rather than a list that guarantees an identity from one matching number.

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