Characterization of hydrogen bonded transients in liquid water and ice by ultrafast infrared pump and x-ray absorption probe spectroscopy

• Applicant: Professor Dr. Philippe Wernet
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2006 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 26519276

Ordinary yet unique, liquid water is probably the most important and least understood substance on earth. A fluctuating network of hydrogen bonds connecting the constantly mobile molecules determines both structure and anomalous properties of water. The hydrogen bonds are strong enough to link the water molecules but they are also weak enough to constantly break and reform on an ultrafast time scale of 1 picosecond (10-12 seconds). Understanding the fast making and breaking of these bonds and the involved molecular rearrangements is a prerequisite for understanding structure and properties of water. We propose to elucidate the making and breaking of hydrogen bonds in water with an unprecedented combination of experimental techniques. The breaking of hydrogen bonds will be initiated by a controlled laser excitation. The subsequent evolution of the hydrogen bond network will be monitored on a molecular level and as a function of time by x-ray spectroscopy in a stroboscopic fashion (pump-probe scheme). This will give unique access to the short-lived early stages in the processes of hydrogen bond breaking and making and it promises to significantly advance our understanding of water.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1134: Transient structures in condensed matter investigated by ultrafast x-ray techniques
• Participating Person: Professor Dr. Wolfgang Eberhardt