The ability to probe energy flow in molecules, following the absorption of ultraviolet light, is crucial to unraveling photophysical phenomena. Here we excite a coherent superposition of vibrational states in the first excited electronic state (S-1) in catechol, resulting in a vibrational wave packet. The observed quantum beats, assigned to superpositions of the low-frequency, and strongly mixed, O-H torsional mode tau(2), elegantly demonstrate how changes in geometry upon photoionization from the S-1 state to the ground state of the cation (D-0) enables one to probe energy flow at the very early stages of photoexcitation in this biological chromophore.
- MULTIREFERENCE PERTURBATION-THEORY
- S-1 STATE