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Generating large starting configurations for molecular Reverse Monte Carlo modelling of an unique non-linear optical amorphous solid
No full textWe report on the recent advances regarding the source code optimization of Reverse Monte Carlo modelling used in scattering data analysis of an amorphous molecular solid which has recently attracted attention as a new brilliant white light emitter if irradiated by a simple infrared laser diode. The algorithm used for generating random molecular starting configurations without overlapping molecules in a box with periodic boundary conditions has been accelerated by a factor of roughly 400 in a 54k atom case. The resulting bigger independent starting configurations are used to gain further insight into previously presented x-ray scattering data. New improved scattering data have been obtained, revealing new structural features in the lower Q range
Spinodal decomposition of reactively sputtered thin films
No full textWe investigate the decomposition mechanisms of metastable cubic (c-)(V0.64Al0.36)0.49N0.51 thin films, grown by reactive high power pulsed magnetron sputtering, by combination of structural and compositional characterization at the nanometer scale with density functional theory (DFT) calculations. Based on thermodynamic considerations of ∂2∆G/∂x2 < 0, spinodal decomposition is expected for c-V1-xAlxN with x ≥ 0.35. While no indications for spinodal decomposition are observable from laboratory and synchroton diffraction data after annealing in Ar atmosphere at 1300 °C, the formation of wurtzite (w-)AlN is evident after annealing at 900 °C by utilizing high energy synchrotron X-ray diffraction. However, the complementary nature of elemental V and Al maps, obtained by energy dispersive X-ray spectroscopy in scanning transmission electron microscopy mode, imply spinodal decomposition of c-(V0.64Al0.36)0.49N0.51 into V- and Al-rich cubic nitride phases after annealing at 900 °C. These chemical modulations are quantified by atom probe tomography and maximum variations of x in V1-xAlxN are in the range of 0.36 to 0.50. The magnitude of the compositional modulations is enhanced after annealing at 1100 °C as x varies on average between 0.30 and 0.61, while the modulation wavelength remains unchanged at approximately 8 nm. Based on DFT data, the local x variation from 0.30 to 0.61 would cause lattice parameter variations from 4.111 to 4.099 Å. This difference corresponds to a shift of the (200) peak from 44.0 to 44.1°. As the maximum decomposition-induced peak separation magnitude of 0.1° is significantly smaller than the measured full width at half maximum of 0.4°, spinodal decomposition cannot be unravelled by diffraction data. However, consistent with DFT predictions, spinodal decomposition in c-(V0.64Al0.36)0.49N0.51 is revealed by chemical composition characterization at the nanometer scale
Revealing the two-electron cusp in the ground states of He and via quasifree double photoionization
No full textWe report on kinematically complete measurements and ab initio nonperturbative calculations of double ionization of He and H2 by a single 800 eV circularly polarized photon. We confirm the quasifree mechanism of photoionization for H2 and show how it originates from the two-electron cusp in the ground state of a two-electron target. Our approach establishes a method for mapping electrons relative to each other and provides valuable insight into photoionization beyond the electric-dipole approximation
PtyNAMi: ptychographic nano-analytical microscope
No full textPtychographic X-ray imaging at the highest spatial resolution requires an optimal experimental environment, providing a high coherent flux, excellent mechanical stability and a low background in the measured data. This requires, for example, a stable performance of all optical components along the entire beam path, high temperature stability, a robust sample and optics tracking system, and a scatter-free environment. This contribution summarizes the efforts along these lines to transform the nanoprobe station on beamline P06 (PETRA III) into the ptychographic nano-analytical microscope (PtyNAMi)
A New Precision Process at FCC-hh: the diphoton leptonic Wh channel
No full textThe increase in luminosity and center of mass energy at the FCC-hh will open up new clean channels where BSM contributions are enhanced at high energy. In this paper we study one such channel, Wh → ℓνγγ. We estimate the sensitivity to the , , and SMEFT operators. We find that this channel will be competitive with fully leptonic WZ production in setting bounds on . We also find that the double differential distribution in the and the leptonic azimuthal angle can be exploited to enhance the sensitivity to . However, the bounds on and we obtain in our analysis, though complementary and more direct, are not competitive with those coming from other measurements such as EDMs and inclusive Higgs measurements
Synthesis and high-resolution spectroscopic studies of Dy in KGdLiF luminescent compound under visible-vacuum ultraviolet radiation
No full textNovel KGdLiF luminescent compounds doped with Dy ions were synthetized. Positions of f-d bands were assigned. It was found that energy transfer from Gd to Dy is not effective. Decay curves of the luminescence originating with the F multiplet in KGdDyLiF for = 0.003, 0.006, 0.012, 0.023.0.047, 0.094, 0.188, 0.375, 0.75 and 1 have been measured as a function of Dy concentration. For diluted sample it reaches ca.1.9 m s whereas for 100 at% it is 1.37 μs? Non-exponential character of Dy decay curves were observed for Dy concentrations larger than x = 0.047. The concentration quenching mechanism were determined. The most efficient luminescence was found for dysprosium concentration within the range 4.7–10 at.%. These phosphors can be easily synthetized at temperatures less than 700 °C. The CIE 1931 coordinates are x = 0.2890, y = 0.3453 (white) at 300 K. It was found that high spin f-d transitions of Dy are 18255 and 20880 cm shifted with comparison to position of Ce d lowest state and possess energies 51400 cm (194 nm) and 54025 cm (185 nm). That values are much higher than postulated in Dorenbos’ model
Load partition during hot deformation of AlSi12 and AlSi10Cu6Ni2 alloys: a quantitative evaluation of the stiffness of Si networks
No full textAn eutectic AlSi12 alloy contains a rigid 3D network formed by the eutectic Si in the as-cast condition, which disintegrates during solution treatment. Synchrotron tomography proved that a near eutectic AlSi10Cu6Ni2 alloy also exhibits a 3D network with higher and more stable stiffness due to the presence of aluminides that retain the initial as-cast microstructure during the solubilization treatment and increase the volume fraction of rigid phases. In order to evaluate the load borne by different phases during hot deformation, in situ synchrotron experiments were carried out revealing an underestimation of the load transfer from the soft α-Al matrix to the hard silicon 3D network in the AlSi12 alloy. By taking into account the additional stiffness introduced by the local interconnectivity, the stresses in different phases in the near eutectic AlSi10Cu6Ni2 alloy were calculated. Additionally, the analysis of the aluminide AlCu allowed to identify its influence in the global damage of the hybrid 3D network formed by the Si and aluminides in the near eutectic AlSi10Cu6Ni2 alloy
Azimuthal single- and double-spin asymmetries in semi-inclusive deep-inelastic lepton scattering by transversely polarized protons
No full textA comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing modulations provide evidence for a sizable worm-gear (II) distribution, . Most of the other modulations are found to be consistent with zero with the notable exception of large modulations for charged pions and positive kaons