Time-dependent structural dynamics of cyclohexadiene probed by strong-field ionization*

We present the results of a time-resolved UV-pump strong-field-ionization-NIR-probe experiment on a prototypical carbon ring molecule, cyclohexadiene (CHD). UV-photoabsorption propels CHD to an electronically excited state, which is coupled to the ground state by a series of conical intersections. Upon de-excitation, the molecule can either return to the initial geometry or isomerize into an open-ring hexatriene (HT) molecule. We discuss possible signatures of the electronic de-excitation and ring-opening in our experimental observables, which include coincident fragment ion yields, kinetic energies, and angular distributions obtained by a coincident ion momentum imaging measurement.