Final Report Summary - VIBCOH (Vibrational coherence as a quantum probe for ultrafast molecular dynamics)
We have developed an experimental setup that uses a sequence of short laser pulses that enables us to initiate a photochemical reaction in a molecular system and to follow how the absorbed photon energy is transferred and dissipated during the induced process. The setup is particularly sensitive to the nuclear motion of the molecule and allows us to resolve even the fastest motion in terms of vibrational spectra. Such spectrum represents a fingerprint of the molecular structure, and thus, yields crucial information about structural changes during the reaction. Based on such measurements, we aim to unravel the specific nuclear motions that promote a rapid and efficient energy transfer. Although extensively studied, the exact underlying mechanisms are still poorly understood.
The molecules studied in this project range from biologically active photoreceptors, such as carotenoids and opsin proteins, to materials proposed as next generation devices for solar energy conversion. A particular highlight of the work is the investigation of the nuclear motion during the process of singlet fission in TIPS-pentacene and its derivatives. The latter represent promising materials for organic solar cells devices which have the ability to convert photon energy into electrical energy much more efficiently compared to traditional silica-based solar cells. Organic materials such as pentacene, use the process of singlet fission to divide the energy of one photon between two molecules, and thereby, generate twice as much charge carriers than traditional solar cells. Using our setup, we were able to reveal the underlying molecular dynamics behind this phenomenon.