Electronic structure of A- and B-site doped lanthanum manganites: a combined X-ray spectroscopic study

The electronic properties of a series of colossal magnetoresistance (CMR) compounds, namely LaMnO3, La(1-x)Ba(x)(MnO3 (0.2 < or = x < or = 0.55), La(0.76)Ba(0.24)Mn(0.84)Co(0.16)O3, and La(0.76)Ba(0.24)Mn(0.78)Ni(0.22)O3, have been investigated in a detailed spectroscopic study. A combination of X-ray photoelectron spectroscopy (XPS), X-ray emission spectroscopy (XES), X-ray absorption spectroscopy (XAS), and resonant inelastic X-ray scattering (RIXS) was used to reveal a detailed picture of the electronic structure in the presence of Ba, Co, and Ni doping in different concentrations. The results are compared with available theory. The valence band of La(1-x)()Ba(x)MnO3 (0 < or = x < or = 0.55) is dominated by La 5p, Mn 3d, and O 2p states, and strong hybridization between Mn 3d and O 2p states is present over the whole range of Ba concentrations. Co-doping at the Mn site leads to an increased occupancy of the e(g) states near the Fermi energy and an increase in the XPS valence band intensity between 0.5 and 5 eV, whereas the Ni-doped sample shows a lower density of occupied states near the Fermi energy. The Ni d states are located in a band spanning the energy range of 1.5-5 eV. XAS spectra indicate that the hole doping leads to mixed Mn 3d-O 2p states. Furthermore, RIXS at the Mn L edge has been used to probe d-d transitions and charge-transfer excitations in La(1-x)Ba(x)MnO3.     

Meeting Report: Ten Years of Atomic and Molecular Science at Elettra

On the 31^st of May and the 1^st of June, 2007, a workshop to celebrate 10 years of atomic and molecular science was held at Elettra. The occasion marked the 10^th anniversary since the first beamtime was officially allocated to a user at the Gas Phase beamline, namely George King of Manchester University. As a satisfied user, King was not only present, but had beamtime during the workshop.     

Kinetics of carbon steel dissolution in ammonium chloride solution containing sodium thiosulfate

The dissolution behavior of carbon steel in ammonium chloride (NH₄Cl) solution containing sodium thiosulfate (Na₂S₂O₃) of various concentrations (0.01 and 0.1 M) was investigated using electrochemical impedance spectroscopy (EIS) and other nonelectrochemical techniques. The weight loss and polarization measurements indicate a significant increase in the NH₄Cl corrosion rate of carbon steel on addition of Na₂S₂O_3. The EIS measurements exhibited two capacitive loops at multiple direct current (dc) potentials for both the concentrations. Electrical equivalent circuit (EEC) and reaction mechanism analysis (RMA) were employed to analyze the impedance data. A four-step mechanism with two intermediate adsorbate species of same charge was proposed to explain the dissolution behavior of carbon steel in the given system. The surface coverage values enumerated that the surface was entirely covered with adsorbed species unlike in the pure NH₄Cl system. Charge transfer resistance and polarization resistance values estimated from RMA parameters indicate the increase in a dissolution rate with dc potential. The surface morphology was inspected via field emission scanning electron microscopy, and the corrosion products including surface state of carbon steel electrode were analyzed using energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.     

A New Route to the Synthesis of N-Formyl Lactams Using Vilsmeier Reagent

A convenient synthesis of N-formyl lactams from the corresponding tetralone and flavanone oximes using Vilsmeier reagent is described.     

Fifth Italian-Australian Workshop on Synchrotron Radiation X-ray Imaging for Life Sciences and Cultural Heritage

Italian and Australian synchrotron scientists came together May 14–15, 2012, at the International Centre for Theoretical Physics in Trieste, Italy, for the latest of a series of topical workshops, the Fifth Italian-Australian Workshop on Synchrotron Radiation X-ray Imaging for Life Sciences and Cultural Heritage. Both scientific communities are interested in applying synchrotron light to solve problems in medicine, zoology, archaeology, art conservation and analysis, palaeontology, and musical instruments.     

A Convenient Access to Chiral Sulfonic Acids

Neomenthyl and trans myrtanyl sulfonic acids are obtained, free from inorganic salts, starting from the corresponding chiral alcohols.     

Cerium oxide stoichiometry alteration via Sn deposition: Influence of temperature

Cerium oxide layers grown on Cu(1 1 1) were studied by conventional X-ray and resonant photoelectron spectroscopy with synchrotron radiation. A quantitative method of determining the cerium chemical state from the Ce 3d photoelectron spectra is described in detail. After the preparation of the ceria layer, Sn films of different thickness were evaporated onto the surface at temperatures of 120, 300 and 520 K. In all three cases, the deposited Sn was oxidized, CeO₂ was partially reduced, and a mixed Sn–Ce–O oxide was formed. The quantitative extent of these reactions was found to be determined by limited diffusion of the deposited Sn atoms into the ceria layer at low temperature. The excess of tin formed a metallic overlayer on the sample surface.     

Synthesis and Characterization of a New Series of Hydroxy Pyrazolines

3-Phenyl-1-(thiophen-2-yl)prop-2-en-1-one obtained by Claisen–Schmidt condensation of 2-acetyl thiophene with benzaldehyde was converted into 2,3-dibromo-3-phenyl-1-(thiophen-2-yl)propan-1-one, which on treatment with various thiosemicarbazides in the presence of triethylamine in absolute ethanol, yielded the corresponding hydroxy pyrazolines 3a–h. All the compounds were characterized by IR, ¹H NMR, and ¹³C NMR spectra.