Single-Electron Subpicosecond Coherent Dynamics in KBrFCenters

The coherent dynamics of a vibronic wave packet in KBr $F$ centers is presented. We observe the temporal evolution of single-electron wave packets following femtosecond laser excitation. Electron dynamics leads to subpicosecond periodic oscillations of the sample transmission. These are monitored in real time by pump-probe techniques yielding directly the vibrational frequencies of the localized modes associated to ground and excited electronic states. These results, complemented by stationary optical characterization, give further insight into the configuration coordinate model for $F$ centers.