Aspects and investigation of photochemical dynamics -- A time-resolved probing method: photoionization -- Simulation of time-resolved photoionization signals -- Simulation: the Norrish type-I reaction in acetone -- Experimental setups -- Paracyclophanes I: [2+2]cycloaddition of ethylenes -- Paracyclophanes II: The Paternò-Büchi reaction -- Probing structural dynamics by interaction between chromophores.

Rasmus Brogaard's thesis digs into the fundamental issue of how the shape of a molecules relates to its photochemical reactivity. This relation is drastically different from that of ground-state chemistry, since lifetimes of excited states are often comparable to or even shorter than the time scales of conformational changes. Combining theoretical and experimental efforts in femto-second time-resolved photoionization Rasmus Brogaard finds that a requirement for an efficient photochemical reaction is the prearrangement of the constituents in a reactive conformation. Furthermore, he is able to show that by exploiting a strong ionic interaction between two chromophores, a coherent molecular motion can be induced and probed in real-time. This way of using bichromophoric interactions provides a promising strategy for future research on conformational dynamics.