Dissecting the hydrogen bond network of water: charge transfer and nuclear quantum effects

The molecular structure of water is dynamic, with intermolecular (H)-bond interactions being modified by both electronic charge transfer and nuclear quantum effects (NQEs). Electronic charge transfer and NQEs potentially change under acidic / basic conditions, but such details have not been measured. Here, we developed correlated vibrational spectroscopy, a symmetry-based method that distinctively separates interacting from non-interacting molecules in self- and cross-correlation spectra, giving access to previously inaccessible information. We found that OH- donated ~8% more negative charge to the H-bond network of water and H3O+ accepted ~4% less negative charge from the H-bond network of water. D2O had ~9% more H-bonds compared to H2O, and acidic solutions displayed more dominant NQEs than basic ones.