Application of resonant X-ray emissions for molecular/electronic structure analysis of boron nitrides
We describe the application of resonant X-ray emissions for molecular/electronic structure analysis of boron nitrides using quasimonochromatic undulator radiation at the Photon Factory. Prominent resonant X-ray emissions due to B1s-B2pπ*-B1s-1 transitions were observed in w-BN composed of four-fold boron atoms and in h-BN composed of three-fold boron atoms, when the photon energy of the incident undulator beams coincided with the B1s-B2pπ* absorption energy. However, no resonance was observed in c-BN composed of four-fold boron atoms. The resonant X-ray emission reflects the electronic structure of unoccupied molecular orbitals which strongly depend on the conformnations of the boron atoms. These findings confirm that resonant X-ray emissions can be useful indices for molecular and electronic structure analysis of boron nitrides.