The photodissociation dynamics of 1,4-diiodobenzene is investigated using ultrafast time-resolved photoelectron spectroscopy. Following excitation by laser pulses at 271 nm, the excited-state dynamics is probed by resonance-enhanced multiphoton ionization with 405 nm probe pulses. A progression of Rydberg states, which come into resonance sequentially, provide a fingerprint of the dissociation dynamics of the molecule. The initial excitation decays with a lifetime of 33 ± 4 fs, in good agreement with previous studies. The spectrum is interpreted by reference to ab-initio calculations at the CASPT2(18,14) level including spin-orbit coupling. We propose that both the 5B1 and 6B1 states are excited initially, and based on the calculations we identify diabatic spin-orbit coupled states corresponding to the main dissociation pathways.
|Journal||The Journal of Chemical Physics|
|Early online date||21 May 2018|
|Publication status||E-pub ahead of print - 21 May 2018|