Ultraschnelle Dynamik von Strukturen und Schwingungen

Aqueous systems display ultrafast structural fluctuations in the time domain between 10^–14 and 10^–11 s, due to the limited strength of hydrogen bonds. Multidimensional ultrafast infrared spectroscopy allows for a time‐resolved observation of such elementary dynamics in bulk water, DNA oligomers and phospholipids. Both the couplings of different vibrational degrees of the hydrated system and bulk water dynamics can be mapped directly. Structural fluctuations of bulk water occur in the time range between 5×10^–14 and 10^–12 s, the breaking and reformation of hydrogen bonds on a time scale of 10^–12 s. At the interface between the water hydration shell and DNA or phospholipids, specific hydration geometries exist for periods of some 10^–11 s with minor fluctuations of their structure. However, a long‐lived 'memory of water' is absent.