Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes

This
study compares two competing pathways of photoexcitations
in gas-phase metal–organic complexes: first, a sequence of
phonon-assisted electronic transitions leading to dissipation of the
energy of photoexcitations and, second, a sequence of light-driven
electronic transitions leading to photolysis. Phonon-assisted charge
carrier dynamics is investigated by combination of the density matrix
formalism and on-the-fly nonadiabatic couplings. Light-driven fragmentation
is modeled by a time-dependent excited-state molecular-dynamics (TDESMD)
algorithm based on Rabi theory and principles similar to the trajectory
surface hopping approximation. Numerical results indicate that, under
the medium intensity of the laser field, light-driven electronic transitions
are more probable than phonon-assisted ones. The formation of multiple
products is observed in TDESMD trajectories. Simulated mass spectra
are extracted from TDESMD simulations and compared to experimental
photoionization time-of-flight (PI-TOF) mass spectra. It is found
that several features in the experimental mass spectra are reproduced
by the simulations.