Ultrafast intracluster reaction in Ba⋯FCH3 excited to the electronic B̃ state

The intracluster reaction initiated in Ba⋯FCH3 by excitation to its electronic B̃ state near 540 nm proceeds on an extremely short timescale. A time constant of (70±10) fs is deduced for the rate-determining step in Ba⋯FCH3 whereas for the deuterated complex Ba⋯FCD3 this time is enlarged to (100±10) fs. By comparison with the results obtained for the reaction via the excited à state at 618 nm a reaction model is suggested which explains the BaF product formation in two successive steps.