In membranes, the interfacial hydrogen bond network is disrupted due to interactions with the lipid headgroups and imbalance of donors and acceptors. In bulk water, the hydrogen bond dynamics are as fast as hundreds of femtoseconds , but the dynamics become slower at the interface as a few picoseconds. In general, disordered water networks exhibit slower reorganization dynamics because the hydrogen bond switching process is a concerted process involving multiple water molecules . However, since the spectrum measures frequency fluctuations, not only hydrogen bond switching, but also local fluctuations in hydrogen bond distances and angles significantly contribute to the measured loss in frequency correlation . Measured dynamics from 2D IR can indicate the changes of water networks at the lipid-water interface and hence the effects of variables such as membrane composition, crowding, or interfacial localization of ions.