We propose a method to steer the outcome of reactive atom-diatom scattering,
using rotational wavepackets excited by strong non-resonant laser pulses. Full
close-coupled quantum mechanical scattering calculations of the D+H2 and F+H2
reactions are presented, where the H2 molecule exists as a coherent
superposition of rotational states. The nuclear spin selective control over
the molecular bond axis alignment afforded by the creation of rotational
wavepackets is applied to reactive scattering systems, enabling a nuclear spin
selective influence to be exerted over the reactive dynamics. The extension of
the conventional eigenstate-to-eigenstate scattering problem to the case in
which the initial state is composed of a coherent superposition of rotational
states is detailed, and a selection of example calculations are discussed,
along with their mechanistic implications. The feasibility of the
corresponding experiments is considered, and a suitable simple two pulse laser
scheme is shown to strongly differentiate the reactivities of o-H2 and p-H2
