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Laser spectroscopic studies of elements in the heavy actinide and transactinide region help understand the nuclear ground state properties of these heavy systems. Pioneering experiments at GSI, Darmstadt identified the first atomic transitions in the element nobelium. For the purpose of determining nuclear properties in nobelium isotopes with higher precision, a new apparatus for high-resolution laser spectroscopy in a gas-jet called JetRIS is under development. To determine the spectral resolution and the homogeneity of the gas-jet, the laser-induced fluorescence of 164Dy atoms seeded in the jet was studied. Different hypersonic nozzles were investigated for their performance in spectral resolution and efficiency. Under optimal conditions, a spectral linewidth of about 200–250 MHz full width at half maximum and a Mach number of about 7 was achieved, which was evaluated in context of the density profile of the atoms in the gas-jet. [ABSTRACT FROM AUTHOR]

We present a crossed molecular beam velocity-map ion imaging study of state-to-state rotational energy transfer of NO(A²Σ+, v = 0, N = 0, j = 0.5) in collisions with Ne atoms. From these measurements, we report differential cross sections and angle-resolved rotational angular momentum alignment moments for product states N' = 3 and 5-10 for collisions at an average energy of 523 cm-1, and N' = 3 and 5-14 for collisions at an average energy of 1309 cm-1, respectively. The experimental results are compared to the results of close-coupled quantum scattering calculations on two literature ab initio potential energy surfaces (PESs) [Pajón-Suárez et al., Chem. Phys. Lett. 429, 389 (2006) and Cybulski and Fernández, J. Phys. Chem. A 116, 7319 (2012)]. The differential cross sections from both experiment and theory show clear rotational rainbow structures at both collision energies, and comparison of the angles observed for the rainbow peaks leads to the conclusion that Cybulski and Fernández PES better represents the NO(A²Σ+)-Ne interaction at the collision energies used here. Sharp, forward scattered (<10?), peaks are observed in the experimental differential cross sections for a wide range of N' at both collision energies, which are not reproduced by theory on either PES. We identify these as L-type rainbows, characteristic of attractive interactions, and consistent with a shallow well in the collinear Ne-N-O geometry, similar to that calculated for the NO(A²Σ+)-Ar surface [Kłos et al., J. Chem. Phys. 129, 244303 (2008)], but absent from both of the NO(A²Σ+)-Ne surfaces tested here. The angle-resolved alignment moments calculated by quantum scattering theory are generally in good agreement with the experimental results, but both experiment and quantum scattering theories are dramatically different to the predictions of a classical rigid-shell, kinematic-apse conservation model. Strong oscillations are resolved in the experimental alignment moments as a function of scattering angle, confirming and extending the preliminary report of this behavior [Steill et al., J. Phys. Chem. A 117, 8163 (2013)]. These oscillations are correlated with structure in the differential cross section, suggesting an interference effect is responsible for their appearance. [ABSTRACT FROM AUTHOR]

Laser spectroscopic studies of elements in the heavy actinide and transactinide region help understand the nuclear ground state properties of these heavy systems. Pioneering experiments at GSI, Darmstadt identified the first atomic transitions in the element nobelium. For the purpose of determining nuclear properties in nobelium isotopes with higher precision, a new apparatus for high-resolution laser spectroscopy in a gas-jet called JetRIS is under development. To determine the spectral resolution and the homogeneity of the gas-jet, the laser-induced fluorescence of 164Dy atoms seeded in the jet was studied. Different hypersonic nozzles were investigated for their performance in spectral resolution and efficiency. Under optimal conditions, a spectral linewidth of about 200–250 MHz full width at half maximum and a Mach number of about 7 was achieved, which was evaluated in context of the density profile of the atoms in the gas-jet.

Laser spectroscopy enables the determination of fundamental atomic and nuclear properties with high precision. In view of the low production rates of the heaviest elements, a high total efficiency is a crucial requirement for any experimental setup to be used in on-line experiments. The setup requires the use of gas stopping techniques to slow down the radionuclides of interest. In previous studies laser spectroscopy was performed inside a gas-filled stopping cell with a limited spectral resolution of a few GHz. Collisional broadening inside stopping cells ultimately limits the precision of laser spectroscopic studies and hampers in particular hyperfine spectroscopy. The spectral linewidth is reduced by an order of magnitude when the laser spectroscopy is performed in a well-collimated gas jet formed by the exit nozzle of a gas stopping cell. In addition, the exposure of the jet to high-repetition rate laser light which saturates the optical transitions allows maintaining a high total efficiency. Here, we present a new setup dedicated to laser spectroscopy of the heaviest elements with an improved resolution, which is presently under construction. This setup combines the efficient filament neutralization demonstrated for nobelium with the improved resolution of in-gas-jet spectroscopy. [ABSTRACT FROM AUTHOR]

Direct high-precision mass spectrometry of the heaviest elements with SHIPTRAP, at GSI in Darmstadt, Germany, requires high efficiency to deal with the low production rates of such exotic nuclides. A second-generation gas stopping cell, operating at cryogenic temperatures, was developed and recently integrated into the relocated system to boost the overall efficiency. Offline measurements using 223Ra and 225Ac recoil-ion sources placed inside the gas volume were performed to characterize the gas stopping cell with respect to purity and extraction efficiency. In addition, a first online test using the fusion-evaporation residue 254No was performed, resulting in a combined stopping and extraction efficiency of 33(5)%. An extraction time of 55(44) ms was achieved. The overall efficiency of SHIPTRAP for fusion-evaporation reaction products was increased by an order of magnitude to 6(1)%. This will pave the way for direct mass spectrometry of heavier and more exotic nuclei, eventually in the region of superheavy elements with proton numbers Z ⩾ 104. [ABSTRACT FROM AUTHOR]

Highlights • The adsorption properties NO and H 2 O 2 on original and Ti-doped Fe 3 O 4 (1 1 1) surface were first studied by DFT calculations. • Ti doping plays a significant role of the catalytic oxidation of NO by H 2 O 2 over Ti-doped Fe 3 O 4 (1 1 1) surfaces. • Oxidation mechanism of NO over Ti-doped Fe 3 O 4 (1 1 1) surfaces by active oxygen was discussed. Abstract Magnetite is considered a promising catalyst for catalytic oxidation of nitrogen oxide (NOx) by vaporized H 2 O 2. The NO oxidation mechanisms on original and Ti-doped Fe 3 O 4 (1 1 1) catalyst surfaces were analyzed by density functional theory, and the individual and combined adsorption characteristics of H 2 O 2 and NO on the original and Ti-doped surfaces were investigated. Results revealed that H 2 O 2 disassociates on the original and Ti-doped surfaces with large adsorption energies. Ti doping significantly augmented the adsorption intensity of H 2 O 2 and promoted the decomposition of H 2 O 2 on the catalyst surface. NO was adsorbed on the original and Ti-doped surfaces in molecular form. The adsorption intensity of H 2 O 2 was greater than that of NO. HNO 2 was generated on the original and Ti-doped surfaces through NO and H 2 O 2 co-adsorption, thereby confirming that NO was oxidized. Analysis of electronic structures demonstrated that H 2 O 2 was decomposed according to the Haber-Weiss mechanism. The oxidation of NO by surface oxygen atoms over the original and Ti-doped surfaces was also calculated, and the low energy barrier obtained suggests that NO is easily oxidized by active O over catalyst surfaces. [ABSTRACT FROM AUTHOR]

The mass distributions of fragments resulting from the fission of the isotopes of Fm and No at excitation energies 0–50 MeV are studied with the statistical scission-point fission model. The available experimental mass distributions in the spontaneous and thermal-neutron-induced fission are well described and the origin of transition between asymmetric and symmetric fission modes with variations of neutron number and excitation energy is explored. [ABSTRACT FROM AUTHOR]

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The hydrogen like ion is the simplest structure of an atom, so the studying on it gives a change to test of methods using for determinating of atomic structures. It is also an occasion the studying on hydrogen like ions to understand atomic structure. For this reason, it is performed a study for hydrogen like nobelium (No101+, Z=102). It has been used both multiconfiguration Hartree-Fock, MCHF, and multiconfiguration Dirac-Fock method, MCDF, as calculating level structure of No101+. The calculations have contained some relativistic corrections and quantum electrodynamic effects. There are very few theoretical works in available literature and no experimental one for No101+. The calculated results have been interpreted in comparison with other theoretical results. [ABSTRACT FROM AUTHOR]

Oxy-H 2 O combustion is a novel oxy-fuel combustion technology, different from conventional and oxy-CO 2 combustion. NO and N 2 O emissions during devolatilization and char combustion of a single biomass particle in O 2 /N 2 and O 2 /H 2 O were investigated in a tube reactor under different temperatures (700 °C, 800 °C, and 900 °C) and oxygen concentrations (21%, 30%, 40%, and 50% by volume). Single biomass pellets of poplar wood, rice husk, and corn stalk were selected. The method of isothermal thermo-gravimetric analysis was applied to distinguish the two stages of biomass combustion based on its proximate analysis. The presence of H 2 O vapor can improve the free radicals, H 2 and CO concentrations, promoting NO and N 2 O reduction. The total conversions of fuel-N to NO and N 2 O in O 2 /N 2 are over 2 times higher than those in O 2 /H 2 O. In O 2 /N 2 , NO is formed as the sample heated up, while N 2 O is mainly formed during char combustion stage. However, NO is formed after N 2 O in O 2 /H 2 O. No matter in O 2 /N 2 or in O 2 /H 2 O, a higher fuel-N content in biomass results in higher NO and N 2 O yields during the two stages, whilst the conversions of fuel-N to NO and N 2 O during the two stages decrease with increasing fuel-N/ash content. In O 2 /N 2 , the total conversion of fuel-N to NO reaches the maximum value (14.35%) at T = 800 °C, whilst the total conversion of fuel-N to NO increases with increasing temperature in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing temperature in O 2 /N 2 and O 2 /H 2 O. The influence of oxygen concentration on NO and N 2 O is similar to that of temperature. In O 2 /N 2 , there is a maximum value of the total conversion of fuel-N to NO (14.35%) at 〈O 2 〉 = 30%, whilst there is no obvious change of the total conversion of fuel-N to NO with increasing oxygen concentration in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing oxygen concentration in O 2 /N 2 and O 2 /H 2 O. The results are beneficial to understand the NO and N 2 O emission mechanisms and favorable for the NO and N 2 O control in O 2 /H 2 O. [ABSTRACT FROM AUTHOR]

A copper complex, [CuI(tmpa)(MeCN)]+, effectively reductively couples NO(g) at RT in methanol (MeOH), giving a structurally characterized hyponitritodicopper(II) adduct. Hydrogen-bonding from MeOH is critical for the hyponitrite complex formation and stabilization. This complex exhibits the reverse redox process in aprotic solvents, giving CuI + NO(g), leading to CuI-mediated NO(g)-disproportionation. The relationship of this chemistry to biological iron and/or copper mediated NO(g) reductive coupling to give N2O(g) is discussed. [ABSTRACT FROM AUTHOR]

In this paper, activity of sol–gel synthesized LaB 0.5 B′ 0.5 O 3 (B = Fe, Mn, B′= Fe, Mn, Co, Cu) perovskite catalysts was evaluated in catalytic reduction of NO by CO. Perovskite catalysts were characterized by XRD, BET, H 2 -TPR and SEM analysis. LaMn 0.5 Cu 0.5 O 3 has the highest activity among LaB 0.5 B′ 0.5 O 3 perovskite catalysts (88% CO conversion and 93% NO conversion at 350 °C). The superior activity of LaMn 0.5 Cu 0.5 O 3 over other perovskite catalysts was associated to synergistic effect between Mn and Cu, higher reducibility at low temperature and more structural defects. The Langmuir–Hinshelwood mechanisms were used for Kinetic modeling of reduction of NO by CO. According to kinetic calculations, the most probable mechanism for this process was found to be the one based on dissociation of adsorbed NO (herein referred to as mechanism 1), according to which the experimental data was predicted at correlation coefficient of R 2 > 0.99. [ABSTRACT FROM AUTHOR]

Using the sensitive Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique an optical transition in neutral nobelium (No, Z = 102) was identified. A remnant signal when delaying the ionizing laser indicated the influence of a strong buffer gas induced de-excitation of the optically populated level. A subsequent investigation of the chemical homologue, ytterbium (Yb, Z = 70), enabled a detailed study of the atomic levels involved in this process, leading to the development of a rate equation model. This paves the way for characterizing resonance ionization spectroscopy (RIS) schemes used in the study of nobelium and beyond, where atomic properties are currently unknown. Graphical abstract: [ABSTRACT FROM AUTHOR]

MoFe/Beta@CeO 2 core−shell catalyst was designed with nano-size Beta supporting MoFe bimetallic oxides as the core and CeO 2 thin film as the shell. The structure and physico-chemical properties of the coated and uncoated CeO 2 catalysts were characterized by TEM, SEM, XRD, N 2 adsorption-desorption, XPS, XANES, ICP-AES, NH 3 -TPD, H 2 -TPR and in-situ DRIFTS. The catalytic activity tests for NH 3 -SCR of NO indicated that the catalyst coated by CeO 2 shell exhibits a remarkable improvement of deNO x activity, excellent tolerance to SO 2 and H 2 O, as well as high thermal stability. The both chemisorbed oxygen species (O 2 − , O − ) and specific surface area increased for the catalysts after the coating of CeO 2 shells. CeO 2 shells not only increase the acid amount but also improve its acid strength, which could be beneficial to improving NO oxidation to NO 2 during NH 3 -SCR. Furthermore, there is a strong interaction among the iron oxides, molybdenum oxides and CeO 2 shells. CeO 2 shells can serve as an effective barrier to inhibit the active metal oxides nanoparticles from aggregating at high temperature. As a result, the coated catalyst with CeO 2 thin film shows a better thermal stability than the uncoated one. What’s more, CeO 2 shells can not only suppress the formation of ammonium nitrate and sulfate species blocking the active iron sites but also restrain the generation of iron sulfate, leading to a higher SO 2 and H 2 O-tolerance. The above results demonstrate that the design of a core−shell structure catalyst is favorable for improving the performance of deNO x catalysts. [ABSTRACT FROM AUTHOR]

A grand challenge in photocatalysis is to seek chemically stable photcatalysts with minimized recombination of photoinduced charges in order to maximize the efficiency of the subsequent redox reactions. Because of the structural noncentrosymmetry, TiO2-based and lead-containing perovskite-type photocatalysts exhibit excellence in both stability and ferroelectricity to facilitate charge separation state. To extend their visible light activity, we use molten salts synthesis methodology to prepare Pb2Bi4Ti5O18 perovskites with various nanoscale morphologies and evaluated their visible light-driven photocatalytic activity for NO removal. The results show that perovskite Pb2Bi4Ti5O18 samples exhibit excellent stability as well as display over 50% NO removal efficiency under visible light in contrast to no more than 15% for commercial P25. A set of radical scavengers were used to probe the reaction mechanism. A bond-valence method was used to calculate the direction and magnitude of the dipole moments of the asymmetric unit in the structure. We revealed that the photocatalytic Pb2Bi4Ti5O18 possesses distorted units in which the dipole-induced internal fields promote the charge separation, leading to the enhanced photocatalytic activity. Because this novel photocatalytic NO removal is a solid-gas reaction in which the lead content is secured in solid phase, this work finds a suitable application for Pb-containing perovskite photocatalysts with great industrial interests and add a new fundamental coordination for better photocatalysts-by-designing. [ABSTRACT FROM AUTHOR]

The experimental determination of atomic levels and the first ionization potential of the heaviest elements ( Z ⩾ 100 ) is key to challenge theoretical predictions and to reveal changes in the atomic shell structure. These elements are only artificially produced in complete-fusion evaporation reactions at on-line facilities such as the GSI in Darmstadt at a rate of, at most, a few atoms per second. Hence, highly sensitive spectroscopic methods are required. Laser spectroscopy is one of the most powerful and valuable tools to investigate atomic properties. In combination with a buffer-gas filled stopping cell, the Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique provides the highest sensitivity for laser spectroscopy on the heaviest elements. The RADRIS setup, as well as the measurement procedure, have been optimized and characterized using the α -emitter 155 Yb in on-line conditions, resulting in an overall efficiency well above 1%. This paves the way for a successful search of excited atomic levels in nobelium and heavier elements. [ABSTRACT FROM AUTHOR]

We investigate the collinear ternary fission of the 260 No isotope. The calculations are performed in the framework of the three cluster model for all possible accompanied light particles of even mass numbers A = 4 − 52 . The folding nuclear and Coulomb interaction potentials are used, based on the M3Y-Reid nucleon–nucleon force for the nuclear part. The deformation of the involved fragments and their relative orientations with respect to each other inside the fissioning nuclei are considered. Among all possible fragmentation channels, the suggested most probable channels are indicated as the ones showing a peak in the Q-value and a local minimum in the fragmentation potential, with respect to the mass and charge asymmetries. The indicated favored fragmentation channels from the approximate spherical calculations and those obtained after considering the deformations of the produced fragments are discussed in detail. In addition to the preferred heavy fragments of closed shells, favored prolate ones of high deformations appear when the nuclear deformations are taken into account. Among indicated fifty six favored channels, a collinear ternary fission of the 260 No isotope is indicated to be most favored through the fragmentation channels of 150 58 Ce+ 4 10 Be+ 40 100 Zr, 60 152 Nd+ 4 12 Be+ 38 96 Sr, 58 150 Ce+ 6 14 C+ 38 96 Sr, 58 148 Ce+ 6 16 C+ 38 96 Sr, 54 140 Xe+ 8 22 O+ 40 98 Zr, 42 106 Mo+ 18 48 Ar+ 42 106 Mo and 41 104 Nb+ 20 52 Ca+ 41 104 Nb. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to seek a surfactant or template-free, simple and green method to fabricate NiO nanobelts and to find an effective technique to detect the ethanol vapor at room temperature.Design/methodology/approach NiO nanobelts with high aspect ratio and dispersive distribution have been synthesized by a template-free hydrothermal reaction at 160°C for 12 h. The products are studied by X-ray diffraction (XRD), energy dispersive spectroscopY, scanning electron microscopy, atomic force microscopy, high-resolution transmission electron microscopy, selective area electron diffractio and X-ray photoelectron spectroscopy. In particular, the room-temperature ethanol sensitivity of NiO nanobelts is investigated by the surface photo voltage (SPV) technique.Findings The prepared NiO nanobelts is single crystalline bunsenite structure with the length of approximately 10 μm and the diameter of approximately 30 nm. The atomic ratio of “Ni” to “O” is 0.92:1. When the concentration of ethanol vapor reaches 100 ppm, the sensitivity of NiO nanobelts is 7, which can meet the commercial demanding of ethanol gas sensor.Originality/value The NiO nanobelts can be obtained by a template-free, simple and green hydrothermal reaction at 160°C for 12 h. The NiO nanobelts-based gas sensor is a promising candidate for the application in ethanol monitoring at room temperature by SPV technique. [ABSTRACT FROM AUTHOR]

We calculate properties of the ground and excited states of nuclei in the nobelium region for proton and neutron numbers of 92 ≤ Z ≤ 104 and 144 ≤ N ≤ 156 , respectively. We use three different energy-density-functional (EDF) approaches, based on covariant, Skyrme, and Gogny functionals, each with two different parameter sets. A comparative analysis of the results obtained for quasiparticle spectra, odd–even and two-particle mass staggering, and moments of inertia allows us to identify single-particle and shell effects that are characteristic to these different models and to illustrate possible systematic uncertainties related to using the EDF modelling. [ABSTRACT FROM AUTHOR]

Pulsing 15N18O onto an annealed 1% Mn16Ox/Ce16O2 catalyst resulted in very fast oxygen isotope exchange and 15N2 formation at 295 K. In the 1st 15N18O pulse, due to the presence of large number of surface oxygen defects, extensive 15N218O and 15N2 formations were observed. In subsequent pulses oxygen isotope exchange dominated as a result of highly labile oxygen in the oxide. [ABSTRACT FROM AUTHOR]

Pulsing 15N18O onto an annealed 1% Mn16Ox/Ce16O2 catalyst resulted in very fast oxygen isotope exchange and 15N2 formation at 295 K. In the 1st 15N18O pulse, due to the presence of large number of surface oxygen defects, extensive 15N218O and 15N2 formations were observed. In subsequent pulses oxygen isotope exchange dominated as a result of highly labile oxygen in the oxide. [ABSTRACT FROM AUTHOR]