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Description
Femtosecond velocity map imaging is employed here to investigate the time-resolved formation of CH2 and Cl (2P3/2,1/2) following from the photodissociation of the CH2Cl radical at 298 nm, in combination with a 800 nm probe to monitor its temporal evolution. The CH2Cl species was generated through photolysis of the a precursor precursor, chloroiodomethane (CH2ICl), by excitation at 268 nm. The I (2P3/2,1/2) fragments resulting from the 268 nm photodissociation of the CH2ICl precursor were detected using resonance-enhanced multiphoton ionization (REMPI) coupled with velocity map imaging (VMI), enabling the determination of the initial internal energy distribution of the CH2Cl radicals. The lifetimes of the excited CH2Cl radical upon excitation at 298 nm were determined by analyzing the temporal evolution of CH2Cl+ ions produced by 800 nm multiphoton ionization as a function of the pump-probe time delay. The transients obtained show an average lifetime of 266 fs for this photodissociation channel. Furthermore, a more detailed analysis demonstrated the existence of multi-dynamic dissociation, since the high internal energy with which the CH₂Cl⁺ radicals were created allows to accessexcitation into the first three excited states. Finally, , oscillations in lifetimes were observed in the experimental transients as reflecting the evolution of the population across the different potential energy surfaces, due to vibrational coherence processes during excitation.