IR and Raman Spectroscopies, Studies of Hydrogen Bonding and Other Physicochemical Interactions

Vibrational spectra are sensitive to intermolecular interactions. This is most clearly evidenced by the differences seen in spectra of condensed phases compared to gases at low pressure which show not just the loss of rotational sidebands but also changes in profile, intensity and position. Hydrogen bonding (H-bonding) provides the most dramatic effects, but even the weak van der Waals forces can significantly modify spectra. In liquids, collisions can distort molecular configuration leading to local breakdown of symmetry. This article describes the hydrogen bonding and other physicochemical interactions studied by infrared and Raman spectroscopy.