Excitation in ion-atom collisions inside subfemtosecond laser pulses

We discuss new excitation mechanisms in energetic ion-atom collisions embedded in short laser pulses. For comparable duration and strength of the pulse and collisional interaction, the laser field will probe and modify the interaction between projectile and target. Coherence effects emerge, insight into reaction dynamics is gained, and new dynamical features are discovered. As an example, we show (i) how a propensity rule for s-p excitation can be dramatically changed, and (ii) how the presence of the laser pulse modifies the ionization process in ion-atom collisions.