What does IR spectroscopy primarily measure?

IR spectroscopy primarily measures the absorption of infrared light by molecules. This technique is based on the principle that molecules vibrate at specific frequencies, which correspond to the vibrational transitions between energy levels. When infrared light passes through a sample, certain wavelengths of the light are absorbed by the molecular bonds within the sample, causing those bonds to vibrate more energetically.

The resulting absorption spectrum displays peaks at wavelengths where absorption occurs, providing valuable information about the functional groups present in the molecules. Each type of bond absorbs infrared light at characteristic wavelengths, enabling the identification of specific chemical structures based on the presence or absence of these peaks. Thus, IR spectroscopy is a powerful tool in organic chemistry for determining molecular structures and understanding functional groups.