Studied in detail, the embedding of hydrophobic molecules in water looks quite different than previously assumed. The inner and outer hydration layers with different properties were referred to as "HB-wrap" and "HB-hydration2bulk" (HB: water hydrogen bond) respectively.
Our joint experimental-theoretical study showed that HCI dissociation at "stardust conditions" is highly sensitive to the sequence in which molecular aggregation takes place. It is expected that this discovery is also a general feature of chemical reactions at ultracold conditions: Sequence matters!
We have been able to shed new light on the properties of water at the molecular level. Our study described accurately the interactions between three water molecules, which contribute significantly to the energy landscape of water. The research could pave the way to better understand and predict water behavior at different conditions.
Ion hydration is relevant to understand a variety of fundamental processes. We find strong indications of non-additive ionic behavior in salt soulutions, thus questioning the simplifying Hofmeister model. For high salt concentrations THz spectroscopy allows us to observe and to quantify ion pair formation.
We showed that water encapsulated in a tiny cage has special properties that are structurally and dynamically distinct from any known phase of water. The water forms a droplet inside the cage that facilitates the encapsulation of a host molecule, i.e. to access the catalytic center. The THz spectrum did not resemble either the spectrum of ice or the spectrum of bulk water.
In the liquid phase, water molecules are connected to one another via hydrogen bonds. Fluctuations in the water network occur on the sub-ps and ps timescale. THz absorption measurements (1 THz = 1012 Hz = 1 ps-1) "see" these dynamic reorientations of dipole moments. This makes THz spectroscopy a sensitive tool to probe solute-induced changes in the collective water network motions.
Ultracold Chemistry: How do molecules aggregate at ultracold temperatures?
Do chemical reactions exist at temperatures barely above absolute zero?
Microsolvation: How many water molecules are necessary to separate ion pairs in acids?