Time-resolved structural dynamics - a challenge for future


Tomáš Polívka


Institute of Physical Biology, University of South Bohemia, Zámek 136, 373 33 Nové Hrady


Knowledge of structure and dynamics of molecular systems is the prerequisite for understanding of function. While static structures of molecules are usually obtained from methods like X-ray crystallography or NMR spectroscopies, information about dynamics is typically obtained from various forms of time-resolved spectroscopies. The most fundamental processes in chemistry and biology usually occur on the ultrafast time scale of femtoseconds to picoseconds. This is the time scale of elementary chemical reactions and of electronic and nuclear motions in molecules, thus this time scale is critical for following the most elementary processes such as bond breaking and formation or electron and energy transfer. Thus, our fundamental understanding of chemical and biological dynamics ultimately relies upon a thorough explanation of the ultrafast processes. Today we combine results from structural and dynamical methods to obtain insight into the function of molecular systems and understanding the molecular mechanisms of dynamic processes. It is a long nourished dream to get both structure and dynamics from the same experiment, i.e. to directly obtain time-resolved structures showing the three-dimensional evolution of a molecular system in the course of a chemical reaction. A number of different techniques are presently pursued towards this goal. Perhaps the most ambitious approach is to extend the present structural methods, X-ray or electron diffraction, to yield 3D structures on the molecular time scale. Besides this ‘direct’ approach, alternative methods for obtaining dynamical structural information, such as time-resolved X-ray absorption or multidimensional coherent femtosecond spectroscopies, emerged in past few years. The aim of this contribution is to give an overview of the state-of-art methods applied nowadays for obtaining dynamical structures of molecules at very short time scales, to compare their pros and cons, and their potential for future applications.