  We study the spectral projection associated to a barrier-top resonance for
the semiclassical Schrodinger operator. First, we prove a resolvent estimate
for complex energies close to such a resonance. Using that estimate and an
explicit representation of the resonant states, we show that the spectral
projection has a semiclassical expansion in integer powers of h, and compute
its leading term. We use this result to compute the residue of the scattering
amplitude at such a resonance. Eventually, we give an expansion for large times
of the Schrodinger group in terms of these resonances.
