Search results for "RET"
showing 10 items of 32883 documents
Direct mass measurements and ionization potential measurements of the actinides
2019
Abstract The precise determination of atomic and nuclear properties such as masses, differential charge radii, nuclear spins, electromagnetic moments and the ionization potential of the actinides has been extended to the late actinides in recent years. In particular, laser spectroscopy and mass spectrometry have reached the region of heavy actinides that can only be produced only at accelerator facilities. The new results provide deeper insight into the impact of relativistic effects on the atomic structure and the evolution of nuclear shell effects around the deformed neutron shell closure at N = 152. All these experimental activities have also opened the door to extend such measurements t…
The research reactor TRIGA Mainz – a strong and versatile neutron source for science and education
2019
Abstract The TRIGA Mark II-reactor at the Johannes Gutenberg University Mainz (JGU) is one of three research reactors in Germany. The TRIGA Mainz became first critical on August 3rd, 1965. It can be operated in the steady state mode with a maximum power of 100 kWth and in the pulse mode with a peak power of 250 MWth and a pulse length of 30 ms. The TRIGA Mainz is equipped with a central thimble, a rotary specimen rack, three pneumatic transfer systems, four beam tubes, and a graphite thermal column. The TRIGA Mainz is intensively used both for basic and applied research in nuclear chemistry and nuclear physics. Two sources for ultra-cold neutrons (UCN) are operational at two beam ports. At …
Model building on the non-factorisable type IIA T6/(Z4×ΩR) orientifold
2016
We construct global semi-realistic supersymmetric models with intersecting D6-branes on the non-factorisable orientifold . The non-factorisable structure gives rise to differences compared to the factorisable case: additional conditions for the three-cycles to be Lagrangian and extra constraints on the wrapping numbers for building fractional cycles.
Measurement of the laser resonance ionization efficiency for lutetium
2019
Abstract The development of a highly efficient resonance ionization scheme for lutetium is presented. A laser ion source, based on the all-solid-state Titanium:sapphire laser system, was used at the 30 keV RISIKO off-line mass separator to characterize different possible optical excitation schemes in respect to their ionization efficiency. The developed laser resonance ionization scheme can be directly applied to the use at radioactive ion beam facilities, e. g. at the CERN-MEDICIS facility, for large-scale production of medical radioisotopes.
Effective characterization of the phase and intensity profiles of asymmetrically distorted light pulses in optical fiber systems
2009
International audience; We address the problem of characterization of light pulses that propagate in long-haul high-bit-rate optical communication systems under strongly perturbed conditions. We show that the conventional technique for characterization of the phase and intensity profile of such pulses becomes qualitatively inconsistent when the pulse's profile is asymmetrically distorted with respect to its center of mass. We resolve these inconsistencies by partially reformulating the conventional technique by means of appropriate pulse parameters, which we call upgraded parameters, that allow a fair characterization of the intensity and phase of all types of light pulses, including those …
Catalytic epoxidation using dioxidomolybdenum(VI) complexes with tridentate aminoalcohol phenol ligands
2019
Reaction of the tridentate aminoalcohol phenol ligands 2,4-di-tert-butyl-6-(((2 hydroxyethyl)(methyl)amino)methyl)phenol (H2L1) and 2,4-di-tert-butyl-6-(((1-hydroxybutan-2-yl)amino)methyl)phenol (H2L2) with [MoO2(acac)2] in methanol solutions resulted in the formation of [MoO2(L1)(MeOH)] (1) and [MoO2(L2)(MeOH)] (3), respectively. In contrast, the analogous reactions in acetonitrile afforded the dinuclear complexes [Mo2O2(μ-O)2(L1)2] (2) and [Mo2O2(μ-O)2(L2)2] (4). The corresponding reactions with the potentially tetradentate ligand 3-((3,5-di-tert-butyl-2-hydroxybenzyl)(methyl)amino)propane-1,2-diol (H3L3) led to the formation of the mononuclear complex [MoO2(L3)(MeOH)] (5) in methanol whi…
The Taming of Redox‐Labile Phosphidotitanocene Cations
2019
International audience; Tame d0 phosphidotitanocene cations stabilized with a pendant tertiary phosphane arm are reported. These compounds were obtained by one-electron oxidation of d1 precursors with [Cp2Fe][BPh4]. The electronic structure of these compounds was studied experimentally (EPR, UV/Vis, and NMR spectroscopy, X-ray diffraction analysis) and through DFT calculations. The theoretical analysis of the bonding situation by using the electron localization function (ELF) shows the presence of π-interactions between the phosphido ligand and Ti in the d0 complexes, whereas dπ–pπ repulsion prevents such interactions in the d1 complexes. In addition, CH–π interactions were observed in seve…
Oxidovanadium(V) amine bisphenolates as epoxidation, sulfoxidation and catechol oxidation catalysts
2017
Air-stable oxidovanadium(V) complexes with tetradentate amine bisphenolate ligands were made by the reaction of VOSO4·xH2O and ligand precursors in MeOH solutions. Isolated compounds were studied as catechol oxidase models as well as catalysts for epoxidation and sulfoxidation reactions. All compounds can catalyse such oxidation reactions without notable structure-activity correlations. The 51V NMR studies indicate that the complexes turn to the number of different species during the catalytic experiments. peerReviewed
Gold/Isophorone Interaction Driven by Keto/Enol Tautomerization
2016
The binding behavior of isophorone (C9H14O) to Au adatoms and clusters deposited on MgO/Ag(001) thin films is investigated by scanning tunneling microscopy (STM) and density functional theory (DFT). The STM data reveal the formation of various metal/organic complexes, ranging from Au1/isophorone pairs to larger Au aggregates with molecules bound to their perimeter. DFT calculations find the energetically preferred keto-isophorone to be unreactive toward gold, while the enol-tautomer readily binds to Au monomers and clusters. The interaction is governed by electrostatic forces between the hydroxyl group of the enol and negative excess charges residing on the ad-gold. The activation barrier b…
2,4,5-Triaryl imidazole probes for the selective chromo-fluorogenic detection of Cu(II). Prospective use of the Cu(II) complexes for the optical reco…
2019
The sensing behaviour toward metal cations and biothiols of two 2,4,5-triarylimidazole probes (3a and 3b) is tested in acetonitrile and in acetonitrile-water. In acetonitrile the two probes present charge-transfer absorption bands in the 320-350 nm interval. Among all cations tested only Cu(11) is able to induce bathochromic shifts of the absorption band in the two probes, which is reflected in marked colour changes. Colour modulations are ascribed to the formation of 1:1 Cu(II)-probe complexes in which the cation interacts with the imidazole acceptor heterocycle. Besides, the two probes present intense emission bands (at 404 and 437 nm for 3a and 3b respectively) in acetonitrile that are q…