Speaker
Description
Evidence of resonant Coulomb explosion imaging induced by low-intensity femtosecond UV-pump UV-probe pulses is presented and applied to the investigation of the methyl iodide molecular dimer, (CH$_3$)$_2$. Since the UV-pump leads to excitation and dissociation of both monomers, and the UV-probe is configured to resonantly enhance ionization of a specic fragment, iodine or methyl, Coulomb repulsion between the two fragment ions takes place, which is detected by velocity map imaging (VMI). The time dependent fragment translational energy distributions are shown to provide relevant information on the initial geometry of the dimer. The experimental results are complemented by electronic structure calculations followed by semiclassical trajectories to further support the proposed approach. The direct correlation between the time-resolved Coulomb explosion trajectories of the nascent fragments and the original dimer geometry exploits a novel methodology for the investigation of cluster dynamics and structural characterization.