Electronic coherences built by an attopulse control the forces on the nuclei

Attopulses have an energy bandwidth broad enough to coherently excite several electronic states of molecules. Towards the control of chemical reactivity by attopulses we derive the quantum mechanical expression for the force exerted on the nuclei in such a vibronic wave packet both during and after the exciting pulse. Tuning the pulse parameters allows accessing specific electronic coherences that determine the force strength and direction during and after the pulse. Following the pulse, the force due to the non adiabatic interactions accelerates or slows down the motion of the vibronic wave packet on the excited electronic states and its sign controls the direction of population transfer. Computational results for the LiH and LiT molecules and the probing by the emission dipole are discussed.