Interactive IR spectrum of aspirin

Click on the peaks, labelled with red markers, to display the corresponding molecular vibration.
The molecule contains 2 carbonyl (C=O) groups, one in a carboxylic acid group and one in an ester group. Both C=O stretches lie at very similar positions in the spectrum and their bands overlap. There is also a band at 3250 cm-1 due to the O-H bond in the acid group.