  Experimentally observed decay rate of the long wavelength Langmuir wave in
metals and dense plasmas is orders of magnitude larger than the prediction of
the prevalent Landau damping theory. The discrepancy is explored, and the
existence of a regime where the forward Raman scattering is stable and the
backward Raman scattering is unstable is examined. The amplification of an
x-ray pulse in this regime, via the backward Raman compression, is
computationally demonstrated, and the optimal pulse duration and intensity is
estimated.
