Time-resolved diffraction and attosecond probing

At this point it becomes more profitable to think in terms of molecular diffraction to supplement spectroscopic analysis. By using time-re solved X-ray diffraction techniques, the molecular dynamics of excited states can, in principle, be observed directly without any knowledge of the PES. This approach is already being employed, using synchrotron radiation, but the time resolution is at present limited to 10 ps (Wulff et al., 2003). However, the development offemtosecond X-ray ffee-electron lasers (e.g. http //tesla.desy.de) will make it possible to obtain diffiaction data on the 

CH19 COHERENT CONTROL AND THE FUTURE OF ULTRA-SHORT PROBING 

However, there will still be a place for spectroscopic studies, as the diffraction studies will raise many questions, such as why one type of molecule proceeds down a particular path whilst other, related molecules proceed down an entirely different path, yielding different products. Spectroscopic studies, which provide information on the force field in a molecule, may well be able to answer such questions when diffraction and spectroscopic studies, together with theory, are combined. Thus, we can expect three strongly coupled parallel streams of research, i.e. time-resolved diffraction, time-resolved spectroscopy and related theoretical studies, to develop over the next decade. 

Further possibilities that are already emerging include the use of lasers with attosecond pulse dura- 

A complete knowledge of the whole mosaic of chemical reactivity needs a full understanding of its most elementary piece, namely that of an elementary chemical reaction occurring in just one event. For this, the molecular beam method is one of the most powerful tools to investigate the dynamics of elementary 

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