Jemna struktura absorpcnich spekter K atomu Fe, Cu, Zn, Ga, Ge, As a Se v ternarnich polovodicich s chalkopyritovou strukturou.

In this work we studied K absorption spectra in two compounds with chalcopyrite structure: CuGaSe2 and CuFeS2. We continued hereby in the studies of binary semiconductors with the sphalerite structure, which had been performed in the laboratory of x-ray spectroscopy in the past decades. For this reason the Cu, Ga and Se K absorption edges in CuGaSe2 were measured and compared with analogous edges in ZnGeAs2 and ZnSe, which were taken from the literature. Furthermore, we measured Cu and Fe K absorption spectra in CuFeS2 to compare them with the Cu and Ga spectra in CuGaSe2. Our goal was to study the bonding of different atoms in the same tetrahedral coordination and especially to study the influence of the transitive element Fe with the unoccupied 3d shell on these bondings. Furthermore, the results were compared with theoretical calculations which had been performed in the Department of Structure Analysis of the Institute of Physics, Prague. The spectra were calculated using a real-space multiple-scattering approach as well as a pseudopotential band-structure technique.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Long-lasting Cadomian magmatic activity along an active northern Gondwana margin: U–Pb zircon and Sr–Nd isotopic evidence from the Brunovistulian Domain, eastern Bohemian Massif

Cadomian magmatic complexes of the Brunovistulian Domain crop out at the eastern termination of the Bohemian Massif. However, the age, nature and geotectonic affinity of some of pre-Variscan (meta-)igneous rock complexes from this domain are still unknown. Geochronological and geochemical study of the granitic rocks across the Brunovistulian Domain reveals new information about the timing and nature of this magmatic activity originally situated along the northern margin of Gondwana. Zircon U–Pb data (601 ± 3 Ma, Brno Massif; 634 ± 6 Ma, paraautochtonous core of the Svratka Dome; 568 ± 3 Ma, Bíteš orthogneiss) from the allochtonous Moravicum indicate the prolonged magmatic activity within the Brunovistulian Domain during the Ediacaran. The major- and trace-element and Sr–Nd isotopic signatures show heterogeneous geochemical characteristics of the granitic rocks and suggest a magmatic-arc geotectonic setting. The two-stage Depleted Mantle Nd model ages (c. 1.3–2.0 Ga) indicate derivation of the granitic rocks from a relatively primitive crustal source, as well as from an ancient and evolved continental crust of the Brunovistulian Domain. These results constrain the magmatic-arc activity to c. 635–570 Ma and provide a further evidence for a long-lived (at least c. 65 Myr) and likely episodic subduction-related magmatism at the northern margin of Gondwana. The presence of granitic intrusions derived from variously mature crustal sources at different times suggests heterogeneous crustal segments to having been involved in the magmatic-arc system during its multistage evolution

Krajina pro chov a výcvik ceremoniálních kočárových koní v Kladrubech nad Labem:Nominační dokumentace UNESCO

Nominační dokumentace Národního hřebčína Kladruby nad Labem pro zápis na Seznam světového dědictví UNESCO