Ultrafast dynamics of isolated fluorenone

Abstract

The ultrafast dynamics of isolated 9-fluorenone was studied by femtosecond time-resolved photoionization and photoelectron spectroscopy. The molecule was excited around 264 - 266 nm into the S6 state. The experimental results indicate that the excitation is followed by a multistep deactivation. A time constant of 50 fs or less corresponds to a fast redistribution of energy within the initially excited manifold of states, i.e., a motion away from the Franck - Condon region. Internal conversion to the S 1 state then proceeds within 0.4 ps. The S 1 state is long-lived, and only a lower bound of 20 ps can be derived. In addition, we computed excited state energies and oscillator strengths by TD-DFT theory, supporting the interpretation of the experimental data. (Figure presented) © 2011 American Chemical Society.