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Ultrafast dynamics of hydrogen bonded structures in condensed matter (ULTRADYNE)
Date du début: 1 mars 2010, Date de fin: 28 févr. 2015 PROJET  TERMINÉ 

Structure-function relationships in condensed matter will be unraveled by studying structural dynamics on atomic length and time scales. The most advanced structure-sensitive methods of ultrafast science such as time-resolved x-ray diffraction and multidimensional vibrational spectroscopy with a temporal resolution better than 100 fs will be applied for mapping fluctuating (macro)molecular structures and photoinduced structural transformations of solids in real-time. The following phenomena will be addressed: (i) Interactions between functional units of individual nucleic base pairs and deoxyribonucleic acid (DNA) oligomers will be determined by multidimensional vibrational spectroscopy. The transfer of excitations in a local geometry and along the double helix, energy dissipation along the helix and into the aqueous environment, as well as the mechanisms of local and global hydration will be studied via the ultrafast response of local vibrations. In this way, hydrogen bonding interactions of water with the DNA backbone and with base pairs are discerned. (ii) Photoinduced structural transformations in prototype hydrogen-bonded solids will be studied by ultrafast x-ray diffraction. The so far unknown dynamics and driving forces of phase transitions in molecular ferroelectrics such as ammonium sulfate and others will be determined by recording transient diffraction patterns after electronic and/or vibrational excitation. A key issue will be the so far unresolved change of the hydrogen bond pattern. This work will include the implementation of new forefront techniques of ultrafast science, e.g., ultrafast x-ray powder diffraction, for a broad range of future applications.

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