RARE-EARTH N4,5 EMISSION-SPECTRA OF SOME RARE-EARTH HEXABORIDES

The rare-earth N4,5 emission spectra of PrB6 and NdB6 were measured to investigate the 4f states. These spectra show some emission peaks abo ve and below the one-electron 4d threshold. The emission spectra are c ompared with existing results of absorption and resonant photoemission . Comparison shows that the emission spectra are composed of two types of 4f --> 4d emission processes, 4d(9)4f(n) --> 4d(10)4f(n-1) + hv an d 4d(9)4f(n+1) --> 4d(10)4f(n) + hv', where n is the number of 4f elec trons in the ground state. The intensity of the 4f --> 4d emission is estimated for light rare-earth hexaborides. This result suggests that the intensity of the 4f --> 4d emission is weaker than the 5p --> 4d e mission.