The coherent dynamics of vibronic wave packets in the green fluorescent protein is reported. At room temperature the nonstationary dynamics following impulsive photoexcitation displays an oscillating optical transmissivity pattern with components at 67 fs $\left(497{\mathrm{cm}}^{-1\mathrm{}}\right)$ and 59 fs $\left(593{\mathrm{cm}}^{-1\mathrm{}}\right)$. Our results are complemented by ab initio calculations of the vibrational spectrum of the chromophore. This analysis shows the interplay between the dynamics of the aminoacidic structure and the electronic excitation in the primary optical events of green fluorescent proteins.

• Received 13 November 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.3439