Quantum dynamical three-dimensional ab initio approach to a femtosecond pump-probe ionization spectrum of Na3(B) at low laser field intensities

The transient femtosecond pump-probe ionization spectrum of Na3 in its B state is simulated for low laser field intensities. All three vibrational degrees of freedom of Na3 have been taken into account in order to calculate a pump-probe spectrum using ab initio potential energy surfaces. The time-dependent wavepacket dynamics elucidate the excitation mechanism during the pump-probe experiment. The dominant oscillations in the ion signal correspond to the motion of a coherent wavepacket along the Qs mode. The theoretical and experimental pump-probe ionization spectra are found to be in good agreement.