Spectroscopy of mass selected clusters
Determination of structure and dynamics of
metal- and semiconductor clusters
Margarita Astruc Hoffmann, Nina Morgner, Markus Maier, Bernd v. Issendorff und Hellmut Haberland 
Cluster physics has two goals: on one hand it studies the development of solid state properties like crystal structure, photoabsorption behaviour or magnetism as a function of cluster size. On the other hand clusters can be used as simple model systems for the examination of fundamental phenomena as e.g. electron-electron correlation or electron-ion-coupling.
In both cases it is necessary to characterize free mass selected clusters as comprehensively as possible. A number of spectroscopical methods are available for this purpose. In our group mainly photoabsorption spectroscopy and photoelectron spectroscopy is used. The first allows one to study excited states, while the latter can be used to determine the electron density of states of the cluster in the ground state. 
Using fs-laser pulses both methods are applied to do time-resolved measurements of ultrafast processes.