Uncharted Waters: Quantifying Hydrogen Bonds in Liquid Water with Correlated Vibrational Spectroscopy

Water’s rapidly changing hydrogen-bond network links molecular interactions to its unusual bulk properties. The talk introduces correlated vibrational spectroscopy (CVS), which combines higher-order optical measurements, symmetry selection and angular polarimetry to isolate signals from interacting molecules and directly examine low-frequency hydrogen-bond stretching.

CVS measurements reveal electronic charge transfer and nuclear quantum effects in water and acidic or basic solutions. Hydroxide donates roughly 8% more negative charge to the network than water, while protons reduce transfer by less than 4%. Nuclear quantum effects weaken hydrogen bonds in pure water by about 10% and change charge transfer in acidic, but not basic, solutions. In acids, charge is accepted locally by a proton and reduced by its delocalization. In bases, donation extends across several hydration shells, beyond the region affected by proton delocalization. The presentation explains how these measurements probe intermolecular correlations and concludes with further applications of CVS.