Lifetime Broadening and Impulsive Generation of Vibrational Coherence Triggered by Ultrafast Electron Transfer

The absorption band shape of chromophores in liquid solution at room temperature is usually dominated by pure electronic dephasing dynamics, which occurs on the sub-100 fs time scale. Herein, we report a series dyads consisting naphthalenediimide (NDI) electron acceptor with one or two phenyl-based donors for photoinduced intramolecular transfer fast enough to be competitive dephasing. As consequence, π–π* transition these broader than that NDI alone an extent scales rate. Additionally, this reaction so it leads impulsive excitation low-frequency vibrational mode charge-separated product. Quantum-chemical calculations suggest vibration involves C–N donor–acceptor bond, shortens considerably upon transfer.