The quantum dynamics of an atomic collision pair interacting with the electric field of an infrared sub-picosecond laser pulse is investigated by means of propagation of representative wavepackets. Depending on the optimal choice of the laser pulse, two competing types of scattering events are encountered. First, for continuum → bound transitions, effective (85 %) vibrationally state-selective photoassociation reactions O + H → OH(ν) are induced by stimulated emission [Chem. Phys. Lett. 260 (1996) 604]. Second, for non-resonant cases, laser controlled acceleration of the colliding atoms can be achieved. Laser field optimization allows to design the energy distribution of the scattered atoms.