Molecular Physics

During the last few decades, molecular physics has gained increasing importance in physics, chemistry and biology. There are several reasons for this progress. The development of new experimental techniques with vastly improved sensitivity and spectral resolution has allowed detailed measurements of structure and dynamics even for large molecules in minute concentrations. This opens the way for studying chemical reactions and biological processes on a molecular level. Using ultrashort laser pulses, very fast dynamical processes in excited molecular states can be measured with a time resolution of a few femtoseconds. Examples are the dissociation of excited molecules, or the redistribution of the energy pumped into a selectively excited molecular state by photon absorption. This energy redistribution onto many vibronic states can be caused by collisions or by couplings between different molecular states, and it often results in a permanent change of molecular structure (isomerization). For the first time in the development of molecular physics, such ultrashort phenomena can be measured in realtime.