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Université de Fribourg

Physical mechanisms and scaling laws of K-shell double photoionization

Hoszowska, Joanna ; Kheifets, A. K. ; Dousse, Jean-Claude ; Berset, Michel ; Bray, I. ; Cao, Wei ; Fennane, Karima ; Kayser, Yves ; Kavčič, Matjaz ; Szlachetko, Jakub ; Szlachetko, Monika

In: Physical Review Letters, 2009, vol. 102, no. 7, p. 073006

We report on the photon energy dependence of the K-shell double photoionization (DPI) of Mg, Al, and Si. The DPI cross sections were derived from high-resolution measurements of x-ray spectra following the radiative decay of the K-shell double vacancy states. Our data evince the relative importance of the final-state electron- electron interaction to the DPI. By comparing the double-to-single...

Université de Fribourg

The paleoecological significance of nerineoid mass accumulations from the Kimmeridgian of the Swiss Jura Mountains

Waite, Richard ; Wetzel, Andreas ; Meyer, Christian A. ; Strasser, André

In: Palaios, 2008, vol. 23, no. 8, p. 548-558

The Kimmeridgian shallow-water carbonates of the Swiss Jura Mountains display stratigraphic levels containing mass accumulations of nerineoidean gastropods. The macro- and microfacies of the rocks with these nerineoidean assemblages suggest that their occurrence was related to water depth, physical energy within the habitat, sedimentation rate, substrate stability, and food supply. Typical...

Université de Fribourg

Morphology, molecular phylogeny, and ecology of Binucleata daphniae n. g., n. sp. (Fungi: Microsporidia), a parasite of Daphnia magna Straus, 1820 (Crustacea: Branchiopoda)

Refardt, Dominik ; Decaestecker, Ellen ; Johnson, Pieter T. J. ; Vávra, Jirí

In: Journal of Eukaryotic Microbiology, 2008, vol. 55, no. 5, p. 393 - 408

We describe a new microsporidian species Binucleata daphniae, n. g., n. sp., that infects the integument cells lining the hemocoele cavity of the carapace and the postabdomen of the cladoceran Daphnia magna Straus. Infected cells filled with spores accumulate as large clusters in the carapace cavity and heavily infected hosts are detected by their opaque appearance. Despite the parasite's...

Université de Fribourg

Double 1s shell ionization of Si induced in collisions with 1–3-MeV protons

Kavčič, Matjaz ; Tökési, K.

In: Physical Review A, 2005, vol. 72, p. 062704

The double 1s ionization of Si induced in collisions with protons was studied by measuring the K x-ray emission of a solid Si target ionized by the impact of 1–3-MeV protons. In order to resolve the hypersatellite contributions corresponding to the radiative decay of the double 1s vacancy state, a high-resolution crystal spectrometer was employed yielding sub-eV energy...

Université de Fribourg

Small-angle neutron scattering on a core-shell colloidal system: a contrast-variation study

Zackrisson, M. ; Stradner, Anna ; Schurtenberger, Peter ; Bergenholtz, Johan

In: Langmuir, 2005, vol. 21(23), p. 10835

Small-angle neutron scattering (SANS) measurements are reported on a sterically stabilized, core-shell colloidal system using contrast variation. Aqueous dispersions of polystyrene particles bearing grafted poly(ethylene glycol) (PEG) have been studied over a large range of particle concentrations and two different solvent conditions for the PEG polymer. SANS data are analyzed quantitatively by...

Université de Fribourg

Modeling properties of molecules with open d-shells using density functional theory

Atanasov, Mihail ; Daul, Claude A.

In: Comptes Rendus Chimie, 2005, vol. 8(9-10), p. 1421-1433

An overview of the theory and applications of a recently proposed ligand-field density functional theory (LFDFT) is given. We describe a procedure based on DFT allowing to deduce the parameters of this non-empirical LF approach consisting of the following steps: (i) an average of configuration (AOC) DFT calculation, with equal occupancies of the d-orbitals is carried out (ii) with...

Université de Fribourg

Paleoecological control of ostracode distribution in a Pennsylvanian Auernig cyclothem of the Carnic Alps, Austria

Fohrer, Beate ; Samankassou, Elias

In: Palaeogeography, Palaeoclimatology, Palaeoecology, 2005, vol. 225(1-4), p. 317

Pennsylvanian (Kasimovian) ostracodes from the lower part of the Auernig Group, Carnic Alps, Austria, inhabited a shallow-marine and open-marine environment. Paleontological investigations of two ostracode faunas brought significant differences between the ostracode assemblage of the Anthracoporella (dasycladalean algae) mound environment and the one from the overlying nodular limestone....

Université de Fribourg

Origin of peloids in Early Cretaceous deposits, Dorset, South England

Samankassou, Elias ; Tresch, Jonas ; Strasser, André

In: Facies, 2005, vol. 51, p. 264

Peloids are ubiquitous components in modern and fossil carbonates. The term peloid is non-genetic because the origin of these grains and the pathways of their formation are not fully understood. Based on Berriasian material originating from Dorset, southern England, we report here on peloids that result from the more or less in-place breakdown of previously micritized bivalve shells. The...

Université de Fribourg

Double 1s shell ionization of Si induced in collisions with protons and heavy ions

Kavčič, M. ; Kobal, M. ; Budnar, M. ; Dousse, Jean-Claude ; Tökési, K.

In: Nuclear Instruments and Methods in Physics Research B: Beam Interactions with Materials and Atoms, 2005, vol. 233(1-4), p. 235-239

The double 1s ionization of Si induced in collisions with protons and heavier ions (C, Ne) was studied by measuring the K X-ray emission of a solid Si target. In order to resolve the hypersatellite contributions in the spectra, high-resolution crystal diffractometry was employed yielding subelectronvolt energy resolution. Experimentally obtained hypersatellite yields were used to determine the...

Université de Fribourg

Double-K-shell ionization of Mg and Si induced in collisions with C and Ne ions

Kobal, M. ; Kavčič, M. ; Budnar, M. ; Dousse, Jean-Claude ; Maillard, Yves-Patrick ; Mauron, Olivier ; Raboud, Pierre-Alexandre ; Tökési, K.

In: Physical Review A, 2004, vol. 70, p. 062720-62730

The satellite and hypersatellite K x-ray emission of a thin Mg foil and thick polycrystalline Si target bombarded by 34-MeV C and 50-MeV Ne ions was measured using high-resolution crystal diffractometry. The corresponding projectile reduced velocities v/vK were 1.09 and 0.92 for C ions and 1.02, 0.86 for Ne ions in case of Mg and Si targets, respectively. An energy resolution of approximately 0.5...