Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes.

Area of Science:

• Physical Chemistry
• Chemical Physics
• Computational Chemistry

Background:

• Photoexcitation in metal-organic complexes can follow two pathways: energy dissipation via phonon-assisted transitions or photolysis via light-driven transitions.
• Understanding these competing dynamics is crucial for controlling photochemical reactions and material properties.

Purpose of the Study:

• To compare the probabilities of phonon-assisted and light-driven electronic transitions in gas-phase metal-organic complexes.
• To model light-driven fragmentation using advanced computational methods and validate against experimental data.

Main Methods:

• Density matrix formalism and on-the-fly nonadiabatic couplings were used to investigate phonon-assisted dynamics.
• A time-dependent excited-state molecular-dynamics (TDESMD) algorithm, based on Rabi theory, modeled light-driven fragmentation.
• Simulated mass spectra were generated from TDESMD trajectories for comparison with experimental data.

Main Results:

• Under medium laser intensity, light-driven electronic transitions were found to be more probable than phonon-assisted transitions.
• The TDESMD simulations predicted the formation of multiple photolysis products.
• Simulated mass spectra showed good agreement with experimental photoionization time-of-flight (PI-TOF) mass spectra features.

Conclusions:

• Light-driven transitions dominate over phonon-assisted pathways in metal-organic complexes under specific laser conditions.
• Computational modeling, particularly TDESMD, is a powerful tool for elucidating photochemical mechanisms and predicting experimental outcomes.
• The study successfully links theoretical simulations to experimental observations, advancing the understanding of photoexcitation dynamics.