Ultrafast Dynamics of Water Molecules Excited to Electronic F States: A Time-Resolved Photoelectron Spectroscopy Study

The ultrafast dynamics of water molecules excited to the two F states is studied by combining two-photon excitation and time-resolved photoelectron imaging techniques. The lifetimes of the F₁A₁ and F₁B₁ states of H₂O (D₂O) were derived to be 1.0±0.3 (1.9±0.4) and 10±3 (30±10) ps, respectively. We propose that the F₁A₁ state mainly decays through the D state, due to the nonadiabatic coupling between them, while the F₁B₁ state decays through the F₁A₁ state via Coriolis interaction.