High field phenomena in thin plasma nitrided SiO2 films

The effects of high field tunnel electron injection on the electrical properties of Al - thin plasma nitrided SiO₂ films - Si (p-type) structures are studied. Under high field injection, it has been observed that electron trapping, positive charge generation near the Si-SiO₂ interface (slow states) and fast state generation at the Si-SiO₂ interface have taken place. After high temperature N₂ annealing, the nitridation induced electron trap density is considerably decreased. Furthermore, under high field injection the generation rate of both the slow states and the interface states and consequently, the degradation rate of the nitrided oxide films have been also decreased after annealing.     

A wave function for the H center in LiF

A wave function for the H center in LiF is proposed, assuming a linear combination of appropriate molecular orbitals. The fitting of theoretical calculations for the hyperfine constants with experimental results shows that the proposed wave function can represent well this defect.     

Predicting points of zero charge of oxides and hydroxides

Pauling's electrostatic valence principle has been applied to describe the surface-charging mechanism of oxides in an aqueous environment. This approach has led to the development of an equation with which one can predict the points of zero charge (PZC) of oxides and hydroxides from crystallographic data. The equation proposed in the present work is an improved version of Parks' PZC equation. The improvements are the following: (i) The equation does not incorporate correction terms to take the cation coordination numbers into account; (ii) the PZC of a complex oxide can be predicted directly from crystallographic data instead of from “assumed” PZCs of its component oxides; and (iii) one can use the mean metal-oxygen bond distance of a crystal instead of the ionic radii tabulated by Parks, which are not consistent with the up-to-date values.     

Double-Resonance Decoupling for Resolution Enhancement of P Solid-State MAS and Al → P MQHETCOR NMR

²⁷Al decoupling has been used to remove residual J-coupling interactions between³¹ P and ²⁷Al in microporous aluminophosphates AlPO₄-14 and AlPO₄-40. In combination with ¹H high-power decoupling, ²⁷Al adapted decoupling yields ³¹P spectra with optimal sensitivity and resolution. The importance of double-resonance decoupling is further demonstrated by incorporating this technique in the MQHETCOR sequence. Unambiguous assignment of all the AlPO₄-14 nuclear magnetic resonances is achieved by combining multiple-quantum evolution in the ²⁷Al dimension and double-resonance decoupling in the ³¹P acquisition domain.     

Electronic distribution of SiO by x-ray spectroscopy

Si Kβ X-ray emission has been comparatively studied in Si, SiO and SiO₂. Taking into account the chemical shift of the inner K level, the position of the valence band of SiO relative to those of SiO₂ and Si has been obtained. The existence of silicon monoxide is confirmed.     

Comparison of heating extraction procedures for Al, Ca, Mg, and Mn in tea samples.

A focused-microwave-assisted procedure was adopted for the extraction of Al, Ca, Mg, and Mn in tea leaves. The efficiency of extraction was evaluated using diluted acids and a water-soluble alkaline tertiary-amines solution. The extraction procedure was implemented in 5 min. A conventional hot-plate digestion procedure was employed for a comparison. A colorless digest was obtained for all tea samples and the total contents determined for each analyte were employed for estimating the efficiency of extraction. Tea infusions were also prepared. Subsequent determinations of Al, Ca, Mg, and Mn were carried out using flame atomic absorption spectrophotometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). In most cases, quantitative, or at least semi-quantitative, extractions were attained for Ca, Mg, and Mn. Lower recoveries were attained to Al, which seems to be related to compounds that bind this element in the sample matrix. Large variations in the trace-element composition of teas were observed; these results are discussed with reference to both extraction media and type of tea.     

Backward elastic scattering and ϱ− production in π−p collisions at 10 GeV/c

The reactions π^?p → p π^? and π^?p → p?^? (?^? → π^?π⁰) at 10 GeV/c with the proton in the forward direction in the c.m.s. are discussed on the basis of 953 elastic scattering events and 2240 events of the reaction π^?p → pπ^?π⁰. The total backward cross sections are 0.52±0.10 and 1.52±0.28 μb, respectively. In both cases the production mechanism is compatible with the dominance of the baryonic Δ_δ Regge trajectory exchange. The ?^? decay angular distributions are studied in the u-channel helicity frame and the spin density matrix elements are presented as functions of u.     

Combined X-ray-Atomic Force Microscopy Tools at the ESRF: The First 10 Years

In the last 10 years, the Surface Science Lab of the ESRF has developed four Atomic Force Microscopes (AFM) compatible with the sample environments of several X-ray beamlines [1 http://www.esrf.eu/UsersAndScience/Experiments/SciInfra/SurfaceSciLab [Google Scholar]], the motivation being to combine many synchrotron-radiation-based techniques with in situ, real-time AFM. To this end, novel experimental techniques and operational schemes particularly adapted to the investigation of nano-sized materials were designed and tested. Several ESRF beamlines have been involved, including ID01, ID03, ID13, ID17, and BM05. This development was initially financed by the European X-Tip project STPR 505634-1 (2004–2008), and then by the French ANR-09-NANO-042 PIANHO Project (2009–2012).     

An in situ atomic force microscope for normal‐incidence nanofocus X‐ray experiments

A compact high‐speed X‐ray atomic force microscope has been developed for in situ use in normal‐incidence X‐ray experiments on synchrotron beamlines, allowing for simultaneous characterization of samples in direct space with nanometric lateral resolution while employing nanofocused X‐ray beams. In the present work the instrument is used to observe radiation damage effects produced by an intense X‐ray nanobeam on a semiconducting organic thin film. The formation of micrometric holes induced by the beam occurring on a timescale of seconds is characterized.     

<Superscript>57</Superscript>Fe Mössbauer,SEM/EDX,p-XRF and μ-XRF studies on a Dutch painting

The painting of a rich Jewish merchant “Bildnis eines jüdischen Kaufmanns” from the Netherlands is dated presumably to the 16^th century. After a vivid historical background, i.e. robbed by the Nazis by order of Hermann Göring, it was recently discovered on an Austrian flea market. Different analysis methods were combined to identify the time of the production of this historically interesting looted art. Non-destructive MIMOS II Fe-57 Mössbauer spectroscopy was utilised for mesurements in selected spots. This mainly revealed haematite (α-Fe₂O₃) in the red curtain. In spots of the brown jacket Mössbauer spectra indicated the presence of mainly Iron(III) in super-paramagnetic oxide or oxide-hydroxide. Consecutively SEM measurements revealed a restoration by partly over-painting. The elementary composition of the pigments was examined by a portable-X-ray fluorescence. μ-XRF analysis for element distribution at different areas was performed. The look into a crack showed Zinc-white at the bottom of the crack. Traces of Titanium-white could be found within some locations on the surface of the painting. In terms of provenance of the artwork, the presence of Zink-white suggests that the painting was painted around the 19^th century. Titanium-white indicates a reconstruction during the 20^th century, approximately between 1917 and 1958.