understanding the deposition of energy from ultrashort (t <50 fsec) laser pulses in an intermediate intensity regime (up to 1016 W/cm2) into isolated molecular systems (atoms, molecules and clusters)
	controlling the excitation, ionization and fragmentation mechanisms of large, finite systems by intense, shaped laser pulses
	understanding  the excitation and decay mechanisms of  highly excited molecular systems

Clusters are between molecules and bulk material and turn into small, transient plasma balls, "nanoplasmas", under intense laser irradiation. Hence, this research bears close relations with the projects 2-01 (relativistic plasma dynamics) and 2-02 (ionization dynamics) but requires both experimentally and theoretically sufficiently specialized tools and methods of its own. On the other hand, a gas of highly ionized clusters is characterized by high local densities in the plasma, but low density on a macroscopic scale. This makes it potentially very attractive as an active medium for X-ray lasers (project 3-04). The high local density is required for creation of inversion in a plasma, e.g. through collisional processes, whereas the low overall density greatly facilitates the propagation of X-radiation through the medium without refraction, one of the most severe loss mechanisms in laser driven X-ray lasers. For all these reasons the investigation of clusters in intense fields is of growing interest in many laboratories. MBI combines in its divisions A and B the necessary background both in cluster research and high intensity laser physics.
 
First experiments use fullerenes which have the advantage that their size and geometry are precisely known /HLS05, BLS05, BLH05, SLS06, LSB06, LSS07a, SLZ08, HSL/.

Recently, pulse-shaping experiments with closed-loop, optimal control feedback have been used to selectively break peptide bonds in small model peptides. The aim is to develop this method into an analytical tool for sequencing of large biopolymers in proteomics /LSS07b, LSS08/.

This work is carried out in the framework of the DFG - Sonderforschungsbereich 450 'Analyse und Steuerung ultraschneller photoinduzierter Reaktionen' Subproject: A2.
Financial support by the Deutsche Forschungsgemeinschaft is gratefully acknowledged.

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