Organic Molecular Chemistry B03

The matrix-isolation technique is used to record high-resolution spectra (electronic absorption and emission as well as infrared) of non-covalently bound aggregates of N-heteropolycyclic aromatics. The molecules are brought from the gas-phase into a frozen film of a polycrystalline noble gas (e.g. Ar or Ne) at low temperatures (4 - 30 K). First, the spectra of individual molecules will be recorded to obtain detailed information about their electronic structure in the absence of intermolecular interactions. Then, aggregation of the molecules is initiated by increase of the concentration and/or by annealing of the matrix host material. The infrared and electronic excitation spectra, and where possible, the fluorescence spectra are compared with the results of quantum-chemical calculations on the aggregate structures.