The vibrational wavepackage dynamics and phase modulation via the resonant Rydberg states in molecules

The observation of vibrational coherence has become significant because it reflects the spatial and temporal localization of a nucleus in a specific mode and characterizes energy flow and multiple kinetic relaxations in chemical dynamics. Vibrational coherence in the S1 state of 2,4-difluoroanisole has been investigated in real time by femtosecond time-resolved photoelectron spectroscopy and time-of-flight mass spectroscopy. Quantum beats of superpositions exhibit temporal oscillations with a frequency of 78 cm-1. Combining the structure computations, oscillations derive from the structure change from planar to nonplanar geometry, which correspond the coherence wavepackets moving from the Franck-Condon region toward the minimum point of the potential energy surface, elucidating the energy flows following the excitation of 2,4-difluoroanisole in the S1 state. The phases of the quantum beat via the resonant Rydberg states exhibit a shift of π rad. The vibrational coherent phase modulation via the resonant Rydberg states will facilitate the chemical coherence control in complex molecular systems.