A sharp and intense structure of the core exciton is observed in total
photon yield spectra of a cubic BN crystal at 192 eV, below the trans
ition from the boron Is level to the conduction-band edge. We have dis
covered, however, that the Raman intensity for leaving behind the vale
nce exciton does not show any enhancement even when the frequency of t
he incident field crosses the core-exciton level. This comes from the
fact that relative magnitudes among the nonlinear channels depend on t
he relevant frequency. We analyzed the Raman spectra taking into accou
nt the strong coupling between the core exciton and radiation fields,
i.e., the polariton effect, Rayleigh scattering, and the Auger process
.