  Stimulated Rayleigh scattering of pump and probe light pulses of close
carrier frequencies is considered. A nonzero time delay between the two pulses
is shown to give rise to amplification of the delayed (probe) pulse accompanied
by attenuation of the pump, both on resonance and off resonance. In either
case, phase-matching effects are shown to provide a sufficiently large gain,
which can exceed significantly direct one-photon-absorption losses.
