The surface vibrational spectrum of water at biological interfaces is often interpreted as having ‘ice-like’ and ‘liquid-like’ components. Here we show that the vibrational spectrum of water at both water–lipid and water–protein interfaces greatly simplifies upon H/D isotopic dilution, which is inconsistent with the presence of ‘ice-like’ structures. The changes in the spectra as a function of isotope content can be explained by intramolecular coupling between bend and stretch vibrations of the water molecules.

Ultrafast Spectroscopy

Bonn, M., Bakker, H., Tong, Y., & Backus, E. (2012). No ice-like water at aqueous biological interfaces. Biointerphases, 7(1-4, Article number: 20), 1–5. doi:10.1007/s13758-012-0020-3