Structure, Reactivity and Dynamics of Clusters

Molecular and ionic clusters are of interest in a wide variety of disciplines, ranging from hetero- and homogeneous processes in atmospheric chemistry to complex electronic phenomena in cluster models of materials science. The meeting brings together researchers from theory and experiment working with clusters of defined size, the structures, kinetics and dynamics of which can be characterized by spectroscopic methods and advanced quantum chemical calculations. Spectroscopic techniques include microwave spectroscopy of small hydrogen bonded systems, photodissociation spectroscopy of ions with mass spectrometric fragment detection, vibrational predissociation spectroscopy using messenger tagging or multiple photon dissociation, as well as photoelectron spectroscopy. Reactivity experiments are conducted in flow tubes or ion traps and analyzed by mass spectrometry. Chemical reaction dynamics of clusters is studied directly by crossed-beam experiments or femtosecond time resolved pump-probe spectroscopy. However, chemical dynamics often modify the outcome of reactivity or photodissociation experiments, and indirect information is obtained by a range of modeling techniques.

One of the appealing aspects of cluster experiments is that modern quantum chemical methods are often capable of treating the complete system, which leads to a very high level of confidence in the comparison of experiment and theory. Small clusters can be described by multiference techniques, while larger systems may require automated geometry optimization via genetic algorithms or machine learning techniques. Such methods afford computer simulations of nucleation processes, which involve clusters of defined size that may feature a plethora of different isomers, or the simulation of material properties with cluster models. High resolution spectroscopy of clusters challenges quantum chemistry and provides benchmarks for the description of non-covalent interactions or metal-metal bonding. The calculation of electronically excited states affords the simulation of electronic absorption spectra and photochemical rearrangements or dissociation.

The interaction of researchers from these diverse backgrounds will stimulate new collaborations and spark new ways for tackling unsolved problems.