POLARISATION DES SPECTRES CARACTÉRISTIQUES D'ÉMISSION X ET ÉTUDE DE LA STRUCTURE ÉLECTRONIQUE DES CORPS SOLIDES

Abstract
The lines (bandes) of X-ray emission spectra of atoms are formed by an energy degenereted components with different polarisation. The energy degeneration of the lines (bands) for atoms in single crystals completely or partialy excludes dependently of the symmetry of crystal and symmetry of the wave functions of initial and final stats of transition. Therefore it is possible by defined mutual orientation of a single crystal-emmitors and crystal-analayser to « switched off » a parts of components with defined direction of polarisation vector of radiative transitions. This directions may be defined by the group theory, if the point symmetry of single crystals is known. It must be pointed out, that the exitation of X-ray spectra can be carried out by electrons as by photons. The excluding the components with different polarisation change all lines (bands) parameters - the frequency shift of maximum intensity, change the energy distribution of intensity. Our experimental investigations of « orientational » dependence of the K- and L-emission lines (bands) from various atoms in different syngle crystals has shown that : the investigation of the atoms X-ray emission spectra in single crystals gives a new and important information about space symmetry of the initial stats wave functions for valence bands ; allow to determine more reliable the « degry of overlapping » the valence bands ; to determine the size of splitting outer and inner atomic levels in crystalain fields. For examples : for single crystal of V₂O₅ the rate of 3 p, 4 p vanadium atomic levels splitting, appreciated from the chift of lines maximum are egnal 1 and 0.8 eV respectively and 1.4 eV for 2 p atomic levels of oxygen. The CHα-band of carbon in graphite has been received only for σ-electron transition.