1,054 research outputs found
Kinetic data for the article "Understanding the Reversible and Irreversible Deactivation of Methane Oxidation Catalysts" Applied Catalysis B: Environment and Energy, 123646
No full textSupporting information to the article "Understanding the Reversible and Irreversible Deactivation of Methane Oxidation Catalysts" by Rasmus Lykke Mortensen,[a,b] Hendrik-David Noack[b], Kim Pedersen,[b] Maja A. Dunstan,(a) Fabrice Wilhelm,(c) Andrei Rogalev,(c) Kasper S. Pedersen,(a)Jerrik Mielby*[a] and Susanne Mossin*[a][a] R. L. Mortensen, Prof. S. Mossin, and Dr. J. Mielby, DTU Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kgs. Lyngby, Denmark, [email protected][b] H.-D. Noack, Dr. K. Pedersen, Umicore Denmark Aps, Kogle Allé 1, DK-2970 Hørsholm, Denmark[c] Dr. Fabrice Wilhelm, Dr. Andrei Rogalev, ESRF – The European Synchrotron, BP 220, 38043 Grenoble Cedex 9, France.</p
Fermi states and anisotropy of Brillouin zone scattering in the decagonal Al-Ni-Co quasicrystal
No full textQuasicrystals (QCs) are intermetallic alloys that have excellent long-range order but lack translational symmetry in at least one dimension. The valence band electronic structure near the Fermi energy E-F in such materials is of special interest since it has a direct relation to their unusual physical properties. However, the Fermi surface (FS) topology as well as the mechanism of QC structure stabilization are still under debate. Here we report the first observation of the three-dimensional FS and valence band dispersions near E-F in decagonal Al70Ni20Co10 (d-AlNiCo) QCs using soft X-ray angle-resolved photoemission spectroscopy. We show that the FS, formed by dispersive Al sp-states, has a multicomponent character due to a large contribution from high-order bands. Moreover, we discover that the magnitude of the gap at the FS related to the interaction with Brillouin zone boundary (Hume-Rothery gap) critically differs for the periodic and quasiperiodic directions
Magnetic Anisotropy of Single-Ion Magnet (PPh4)2 [ReF6]·2H2O
No full textStudying of single-molecule magnets has sprung many surprises such as, e.g., quantum tunneling of the magnetization, which is strongly related to the presence of a magnetic anisotropy. Electron spin resonance and inelastic neutron scattering measurements of (PPh4)2[ReF6]⋅2H2O complex evidence an unprecedented large single-site magnetic anisotropy of D ∼ 35 K in this material. Using state-of-the-art ab initio calculations we found that the single-ion anisotropy is indeed very large (but does not exceed 12 K) and revealed the physical mechanism lying behind this phenomenon. © 2023, The Author(s).Ural Branch, Russian Academy of Sciences, UB RASWe are grateful to Prof. A. Rogalev for drawing our attention to this Re SIM and E. Komleva for a detailed discussion of the paper. Computations were performed on the Uran supercomputer at the Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences
Contribution of Electromagnetic Interactions into the Transverse Polarization of the Muon in the Decay
No full textGrowth and characterisation of uranium multilayers.
No full textThis thesis investigates the extents of the 5f-3d and 5f-4f electronic interactions in U/Fe, U/Co and U/Gd thin films, where electronic hybridisation effects are expected to influence the magnetism of the U 5f states. The samples were prepared by DC magnetron sputtering and included niobium buffer and capping layers to instigate crystalline growth and prevent oxidation of the multilayer stack. Layer thicknesses were varied between 5A and 90A with up to 30 bilayer repeats. The majority of the samples were grown at room temperature, but selected compositions were grown at elevated substrate temperatures. Many well-defined Bragg peaks were evident in the X-ray reflectivity spectra of multilayers of all three systems, indicating a low impurity contamination and a well-reproduced bilayer structure. High-angle X-ray diffraction spectra of the transition metal multilayers revealed poorly crystalline, oriented transition metal layers with a non-crystalline component of Fe and Co of 17A. U/Gd X-ray diffraction spectra displayed intensities up to two orders of magnitude greater than those observed for U/Fe or U/Co samples of similar composition and contained satellite peaks, indicating some degree of coherency between the two species. An intense peak was observed, arising from a crystalline uranium component at a position close to that expected for an exotic hep U phase, oriented in the 001 direction. Bulk magnetisation measurements revealed magnetically 'dead' Fe and Co layers of 15A and magnetic moments tending towards the bulk values of 2.2/zb and 1.7/iB for thick Fe and Co layers respectively. A study of the bulk magnetic properties of the U/Gd system did not indicate the presence of any significant 'dead' layer, but reported a saturation magnetic moment for thick Gd layers of 4.5//b> considerably reduced from the bulk value of 7.63//B- Calculations of the magnetic anisotropy for U/Gd samples revealed a possible transition from the gadolinium moments aligned within the plane of the film to samples displaying perpendicular magnetic anisotropy (PMA), at a gadolinium layer thickness of 5A. This transition could be achieved for thicker Gd layers if the thickness of the U layers were increased. A finite-size scaling effect was observed in a gadolinium layer thickness dependent study of the Curie temperature, indicating a transition from three to two dimensional behaviour for very thin Gd layers. Polarised neutron reflectivity spectra were taken in the specular geometry at magnetic saturation, and were simulated with separate, reduced moment and bulk moment ferromagnetic layers for U/Fe and U/Co samples and a simple bilayer structure for U/Gd samples. This simultaneous measurement of both the physical composition and bulk magnetisation measurements supported results obtained by X-ray reflectivity and magnetometry. The hybridisation of the electronic states in U/Fe and U/Gd resulted in an induced polarisation, detected using element selective techniques. X-ray magnetic circular dichroism measurements at the U Mrv and My edges were used to investigate the spin and orbital components of the uranium magnetic moment and a total magnetic moment on the U site of 0.1/b for the case of U/Fe multilayers, 0.01/zb in U/Gd samples and a signal only barely detectable above the statistical noise in the U/Co system were revealed. A uranium layer thickness dependent study of the magnetic moment values was used to indirectly deduce the profile of uranium magnetisation within the layers. X-ray resonant magnetic reflectivity measurements provided a depth dependent measure of the induced U 5f moment for selected U/Fe samples, which indicated a more complicated interfacial structure than that deduced by X- ray and neutron reflectivity techniques and showed that the majority of the U 5f moment was located at the interface region
Catalogue of Lepidoptera of Omsk Region (Russia). Microlepidoptera. Families: Eriocraniidae, Nepticulidae, Opostegidae, Adelidae, Prodoxidae, Incurvariidae, Psychidae, Tineidae, Roeslerstammiidae, Bucculatricidae, Gracillariidae, Yponomeutidae, Argyresthiidae, Plutelliidae, Acrolepiidae, Glyphipterigidae, Ypsolophidae, Lyonetiidae, Bedelliidae, Ethmiidae, Depressariidae, Elachistidae, Parametriotidae, Scythrididae, Chimabachidae, Cryptolechiidae, Oecophoridae, Batrachedridae, Coleophoridae, Momphidae, Blastobasidae, Autostichidae, Cosmopterigidae, Gelechiidae, Pterophoridae, Epermeniidae, Choreutidae, Galacticidae, Tortricidae, Pyralidae, Crambidae
No full textA total of 781 species of Microlepidoptera belonging to 41 families are reported for the territory of Omsk Region. The most numerous is the Tortricidae family represented by 255 species, then Crambidae (94 species), Gelechiidae (70), Pyralidae (66), Pterophoridae (44), Depressariidae (32), Gracillariidae (29), Tineidae (25), Elachistidae (14), Adelidae and Elachistidae (8 species in each family), Yponomeutidae, Ypsolophidae, Ethmiidae and Cosmopterigidae (7 species in each family), Scythrididae and Oecophoridae (6 species in each family), Eriocraniidae (4), Nepticulidae, Momphidae and Epermeniidae (3 species in each family), Prodoxidae, Glyphipterigidae, Lyonetiidae and Choreutidae (2 species in each family), Opostegidae, Incurvariidae, Roeslerstammiidae, Argyresthiidae, Plutelliidae, Acrolepiidae, Bedelliidae, Parametriotidae, Chimabachidae, Cryptolechiidae, Batrachedridae, Blastobasidae, Autostichidae, Galacticidae (1 species in each family). 10 species are new to the Omsk Region. Agonopterix purpurea (Haworth, 1811) and Aethes flagellana (Duponchel, 1836) are reported from the territory of Omsk Region as new to the Asian Part of Russia; Fomoria weaveri (Stainton, 1855) reported from the territory of West Siberia for the first time.The author is thankful to colleagues and friends: S.Yu. Sinev, A.L. Lvovsky, S.V. Baryshnikova (all from St. Petersburgh), V.V. Dabatolov, O.E. Kosterin, P.Ya. Ustjuzhanin (all from Novosibirsk), R.V. Yakovlev (Barnaul), V.V. Anikin (Saratov), N.I. Kirichenko (Krasnoyarsk), E.J. van Nieukerken (Leiden, The Netherlands), M.G. Ponomarenko (Vladivostok) for their help with determination and useful disscussions on this project; K.B. Ponomarev, V.V. Rogalev, S.M. Saikina (all from Omsk), V.Yu. Teploukhov (Bolshiye Uki, Omsk Oblast), O.N. Kholodov (Krasnyi Oktyabr`, Omsk Oblast), A.A. Salnik (Ermak, Omsk Oblast), for their valuable help, good company during the expeditions and data supply
Disentangling bulk and surface Rashba effects in ferroelectric alpha-GeTe
No full textMacroscopic ferroelectric order in alpha-GeTe with its noncentrosymmetric lattice structure leads to a giant Rashba spin splitting in the bulk bands due to strong spin-orbit interaction. Direct measurements of the bulk band structure using soft x-ray angle-resolved photoemission (ARPES) reveals the three-dimensional electronic structure with spindle torus shape. By combining high-resolution and spin-resolved ARPES as well as photoemission calculations, the bulk electronic structure is disentangled from the two-dimensional surface electronic structure by means of surface capping, which quenches the complex surface electronic structure. This unravels the bulk Rashba-split states in the ferroelectric Rashba a-GeTe(111) semiconductor exhibiting a giant spin splitting with Rashba parameter alpha(R) around 4.2 eV angstrom, the highest of so-far known materials
A high resolution, 6 channels, silicon drif detector array with integrated JFET's designed for XAFS spectroscopy:first X-ray fluorescence excitation spectra recorded at the ESRF
No full textMagnetic properties of the (Mo2/3R1/3)2AlC(R=Ho,Dy ) i-MAX phases studied by x-ray magnetic circular dichroism and neutron diffraction
No full textInternational audienceWe report on the magnetic properties of single crystals of Ho- and Dy-based (Mo2/3R1/3 )2AlC i-MAX phases.In these nanolamellar compounds, where planes of R and Mo arranged in a skewed triangular lattice are separated by planes of Al and C, geometrical frustration and magnetic exchange interactions lead to complex magnetic properties. Temperature-dependent bulk magnetization, specific heat, and resistivity measurements reveal two magnetic phase transitions in Dy i-MAX (15 and 12 K) and only one in Ho i-MAX (8.5 K). Strong magnetic anisotropy and metamagnetic transitions with a step at 1 3 of saturation moment along the crystal a axis are observed in field-dependent bulk magnetization curves. X-ray magnetic circular dichroism measurements unveil induced moments on Mo and Al, and a quantitative estimation of the orbital and spin moments of Mo based on magneto-optical sum rules suggests an unusual interaction between the R 4 f and the Mo 4d magnetic moments. Magnetic structures are derived from neutron diffraction measurements, revealing a zero-field incommensurate amplitude modulated order in both compounds, followed by an antiferromagnetic equal-moments structure at lower temperature for Dy i-MAX. The bulk magnetization 1/3 step is found to be linked to the flip of one R moment out of three within the planes. Detailed phase diagrams for Ho and Dy i-MAX are derived from these measurements
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