Work Group Prof. Dr. F. Temps

Photolysis of carbonyl compounds

The Walsh type I C-C bond fission reaction of ketones is a classic example of a photochemical reaction. It is of great imprtance in the Earth's atmosphere and as a source of methyl radicals in organic chemistry. At shorter photolysis wavelengths, the acetyl co-product may carry enough internal energy to undergo secondary unimolecular dissociation. The wavelength-dependent branching ratio between formation of CH3 + CH3CO and CH3 + CH3 + CO has long been debated. Since the two methyl fragments are formed with different kinetic energies, the method of velocity-mapped photofragment imaging used in our laboratory provides valuable insight into the dynamics of acetone and many acetone derivatives. 

With the advent of first femtosecond time-resolved data on acetone, severe questions arose about the previously accepted photodissociation mechanism via the triplet state of acetone. Using femtosecond photoelectron imaging, we have recently been able to demonstrate the involvement of Rydberg state.