Photodynamics of N-and N,B-Containing Polycyclic Aromatic Hydrocarbons and their Clusters: A Free Electron Laser Study

PANH (nitrogen-containing polycyclic aromatic hydrocarbons) are of considerable interest in optoelectronics as electron-conducting materials, but also in interstellar chemistry, where they are considered as carriers of the unidentified infrared bands.

In this talk I will focus on two molecules that serve as models for their photodynamics. The first one is phenanthridine, the second one is an azaborine. Labotatory investigations of these compounds are challenging, because inserting heteroatoms in aromatic molecules complicates the photochemistry by introducing nπ* states that are difficult to probe by laboratory laser sources. Therefore, we investigate the molecular dynamics after UV excitation by time-resolved X-ray photoelectron (TR-XPS) and X-ray absorption (TR-XAS) spectroscopy at the N and B 1s edge, using X-ray free electron laser (FEL) radiation. In cooperation with theory, detailed insight into the photodynamics is obtained. Molecular dimers are in turn characterized by IR/UV spectroscopy. Here, an FEL operating in the IR is employed.