  The non-dispersed soft x-ray emission from a La/B4C periodic multilayer
irradiated by monochromatic x-rays has been measured as a function of the
incident photon energy in the 125-200 eV range for different scattering angles.
We have observed a scattered intensity peak at incident energies which shift
towards the low-energy side as the value of the scattering angle increases.
These observations are interpreted as Raman scattering by the 5p level of
lanthanum assisted by Bragg diffraction from the lattice of the periodic
multilayer. A simple model based upon the laws of energy and momentum
conservation enables us to account for the variation of the incident energy
associated with the Bragg-Raman peak.
