ORIENTATION DEPENDENCE OF X-RAY REFLECTION FROM BNHEX IN THE ENERGY REGION OF B AND N K-EDGES

The reflection spectra fine structure from two surfaces of the hexagon al BNhex cut parallely and perpendicularly to the c-axis of the crysta l in the energy region 40-850 eV, i.e. including the B-K and N-K absor ption edges, have been obtained for different angles of incidence usin g s-polarized synchrotron radiation. The B-K and N-K absorption spectr a fine structure for both crystal orientations were calculated from th e reflection spectra at 86 degrees using the Kramers-Kronig dispersion relations and were combined in a common scale by means of XPS-data. A strong orientation dependence of both reflection and absorption spect ra was found. The comparison of the B-K and N-K absorption spectra lea ds to the following conclusion the N-K-spectra demonstrate features si milar to the B-K-spectra, that means both B and N 2p states participat e in the formation of N2p pi(), B2p pi(*), N2p sigma(*) and B2p sigma () resonance states in BNhex.