The Cosmochemical Cycle of Organic Matter

Hydrocarbons of all shapes and sizes are found throughout the various stages of star- and planet formation. Recently, using radio astronomical observations, a variety of cyclic- and even polycyclic hydrocarbons have been detected in the very cold (10 K) Taurus molecular cloud. These detections challenge our understanding of the chemical formation mechanisms under these low-temperature and low-density conditions. In photon-dominated regions, on the other hand, very large Polycyclic Aromatic Hydrocarbons (PAHs) of 50 carbon atoms and larger are commonly detected as a class based on the characteristic mid-infrared emission bands that they emit after being electronically excited by ultraviolet and optical radiation. These large PAHs are exposed to a very strong radiation field that can alter their molecular structure and may even lead to dissociation. In this seminar, I will show how experimental studies using synchrotron and free electron laser radiation – in conjunction with quantum chemical computations – allow us to reveal the formation and dissociation mechanisms of interstellar (aromatic) hydrocarbons at a molecular level of detail.