  We study experimentally interaction-driven spin oscillations in optical
lattices in the presence of an off-resonant microwave field. We show that the
energy shift induced by this microwave field can be used to control the spin
oscillations by tuning the system either into resonance to achieve near-unity
contrast or far away from resonance to suppress the oscillations. Finally, we
propose a scheme based on this technique to create a flat sample with either
singly- or doubly-occupied sites, starting from an inhomogeneous Mott
insulator, where singly- and doubly-occupied sites coexist.
