Distinct water species confined at the interface of a phospholipid membrane

The physics of confined water has stimulated extensive research in recent years, in particular, regarding the role of hydrogen bonding as a significant factor in the observed dynamics. In this work, two-dimensional infrared spectroscopy was employed to investigate the response of the OH moiety of water in phospholipid membrane samples. The results show strong evidence for three distinct hydrogen bonding motifs (H2O with zero, one, or both OH moieties hydrogen bonded), whose relative proportions at the membrane interface are estimated.