X‐ray spectroscopic investigation of beryllium by polarized K‐emission valence bands

A theory of polarized K‐emission bands is given and a special method of measuring the spectra by means of a grating spectrometer is described. In this way polarized components of the radiation emitted by a monocrystalline sample are recorded. The spectra of optically anisotropic crystals measured in such a way possess a higher content of information by additional applicable selection rules for polarized radiation compared with the spectra of polycrystalline samples. In the case of the polarized Be K‐emission valence bands conclusions can be drawn on the existence of bonding charges. A more unambiguous correlation of spectra structures with van Hove singularities of the band structure provides a better experimental check up of several recent band structure calculations for metallic beryllium. This is especially demonstrated for the discontinuities at the points Γ and M .