The clusters are studied with laser spectroscopy under isolated conditions both at very low temperatures in supersonic beams and at room temperature in a cell. They typically consist of an aromatic molecule with solvent molecules (microsolvated molecules).

Small clusters are selected in size and structure by resonant two photon ionization (R2PI) with pulsed UV lasers and massspectrometry. With infrared lasers we are able to measure the fingerprint vibrations of the cluster and in particular of its solvent moiety, from which its structure is determined by computer simulation of the vibrational spectra

We these laser methods we study fundamental photo reactions or ion-molecule reactions under controlled microsolvation.
Examples: charge, hydrogen and energy transfer or chemical reactions

With ultrashort pico- and femtosecond laser we observe in real-time the rotation of a cluster or large molecule, from which the structure may be deduced by computer simulation. By time-resolved photoelectron spectroscopy photoreactions may be investigated in real-time.

In liquid phase also weakly bound complexes are formed, the most prominent ones being that of biomolecules in solution. These generally form very specific complexes by molecular recognition ( e.g. enzyme-substrate, receptor-ligand complexes). Binding constants can be determined in situ by fluorescence correlation microscopy. This project is part of the Frankfurt Sonderforschungsbereich SFB 579: RNA-Liganden Wechselwirkungen

To detect these noncovalent bonded species mass spectrometrically, we developed a soft and ultrasensitive laser desorption technique, where ions are laserdesorbed from tiny droplets or from micro liquid beams into vacuum where they are analyzed with mass spectrometry. This project is part of the Frankfurt Sonderforschungsbereich SFB 579: RNA-Liganden Wechselwirkungen