Intensity analysis of boron and nitrogen K‐edge spectra for hexagonal boron nitride by EELS

SUMMARY Boron and nitrogen K‐edge spectra for hexagonal boron nitride (h‐BN) were measured by electron energy loss spectroscopy (EELS) at orientations of a momentum transfer q parallel and perpendicular to the c‐axis in order to investigate anisotropic unoccupied states π* and σ*, separately. Differences between intensity profiles for B K and N K spectra are attributed to different transition probabilities at B K and N K edges from Is states to the π* and σ* states. The intensity of the first peak at q ∥ c in the B K spectrum, which is ascribed to the transition from B‐1s to the Q — 2 state in the π* band, is 10 times as large as that in the N K spectrum. Quantitative calculation of transition probabilities for B K and N K spectra at q ∥ c shows that the contribution of B‐2p z orbital to the Q — 2 state is 1–7 times as large as that of N‐2p z . This value suggests that the enhanced peak in the B K spectrum is explained by means of single electron excitations, disregarding the electron‐electron interactions for the exciton reported by several workers. The contributions of 2p x and 2p y orbitals of B and N atoms to σ* states are also estimated by intensity analysis of B K and N K spectra at q⊥c .