24 research outputs found
First description of a fossil chamaeleonid from Greece and its relevance for the European biogeographic history of the group
The fossil record of Chamaeleonidae is very scarce and any new specimen is therefore considered important for our understanding of the evolutionary and biogeographic history of the group. New specimens from the early Miocene of Aliveri (Evia Island), Greece constitute the only fossils of these lizards from southeastern Europe. Skull roofing material is tentatively attributed to the Czech species Chamaeleo cf. andrusovi, revealing a range extension for this taxon, whereas tooth-bearing elements are described as indeterminate chamaeleonids. The Aliveri fossils rank well among the oldest known reptiles from Greece, provide evidence for the dispersal routes of chameleons out of Africa towards the European continent and, additionally, imply strong affinities with coeval chamaeleonids from Central Europe
Oxygen -spectra and electronic structure of the oxyanions , TeO_{3}^{2−}SO_{4}^{2−}, TeO_{4}^{2−}$
Molecular orbital analysis of the ion by studies of the anisotropic -ray emission of its components
OPTICAL ABSORPTION OF SOLID NEON AND ARGON IN THE SOFT X-RAY REGION
Les spectres d'absorption de couches minces d'Ar et de Ne solide ont été mesurés pour des photons de 25 à 500 eV. On a également étudié le spectre correspondant pour les gaz pour comparer à l'état atomique. La source de lumière était le synchroton à électrons DESY de 7,5 GeV. Au voisinage des transitions depuis les couches internes (2 s dans Ne, 3 s et 2 p dans Ar) on peut voir une structure fine caractérisant l'état solide ou l'état atomique. La structure dans le spectre du solide est attribuée à un exciton et une transition interbande. L'absorption vers le continuum à quelque distance des différents seuils est très semblable dans le solide et le gaz.The absorption spectra of thin films of solid Ne and Ar have been measured in the photon energy range 25 to 500 eV. For comparison with the atomic states the corresponding spectra in the gas have also been investigated. The 7.5 GeV electron synchroton DESY served as light source. Near the onset of inner shell transitions (2 s in Ne, 3 s and 2 p in Ar) fine structure can be seen which is characteristic for the solid or atomic state. The structure in the spectra of the solid is ascribed to exciton and interband transitions. The absorption in the continuum at some distance from the various thresholds shows great similarities between the solid and gaseous states