Alloying by high dose ion implantation of iron into magnesium and aluminium

Alloys of the systems Fe–Al (mixable over the whole concentration range) and Fe–Mg (insoluble with each other) were produced by implantation of Fe ions into Al and Mg, respectively. The implantation energy was 200 keV and the ion doses ranged from 1 × 10₁₄ to 9 × 10₁₇cm^-2The obtained implantation profiles were determined by Auger electron spectroscopy depth profiling. Maximum iron concentrations reached were up to 60 at.% for implantation into Al and 94 at.% for implantation into Mg. Phase analysis of the implanted layers was performed by conversion electron Mössbauer spectroscopy and X‐ray diffraction. For implantation into Mg, two different kinds of Mössbauer spectra were obtained: at low doses paramagnetic doublets indicating at least two different iron sites and at high doses a dominant ferromagnetic six‐line‐pattern with a small paramagnetic fraction. The X‐ray diffraction pattern concluded that in the latter case a dilated αiron lattice is formed. For implantation into Al, the Mössbauer spectra were doublet structures very similar to those obtained at amorphous Fe–Al alloys produced by rapid quenching methods. They also indicated at least two different main iron environments. For the highest implanted sample a ferromagnetic six‐line‐pattern with magnetic field values close to those of Fe₃Al appeared.     

Negative molecular ions of azafullerenes and their hydrogenated derivatives

The formation and decay of negative molecular ions of azafullerenes and their hydrogenated derivatives are investigated by mass spectrometry. The mechanisms of resonant electron capture and the lifetimes of negative molecular ions with respect to the electron autodetachment in azafullerene molecules are discussed. A comparative analysis of the data obtained for azafullerenes and hydrogenated fullerene derivatives is carried out.     

Quantification of Secondary Fe-Phases Formed During Sorption Experiments on Chlorites

Hyperfine Interactions - During batch sorption experiments of heavy metals on chlorite not only sorption reactions take place, but also reactions of chemical weathering leading to mineral...     

Magnetic structure of Fe−Si−Al films implanted with Al and N ions

Changes in the magnetic structure of Fe–Si–Al films due to Al and N ion implantation were studied by⁵⁷Fe Conversion Electron Mössbauer Spectrometry (CEMS). The peaks of the magnetic sextets due to the crystalline films became broader by implantation with 5×10¹⁶ Al/cm², suggesting the formation of amorphous phases. In the CEM spectrum of one sample with large grains implanted with 1×10¹⁷ Al/cm² a crystalline -Fe phase appeared. N implantation with the same dose did not amorphize the sample but the components with high magnetic hyperfine fields were enhanced.     

CEMS and DCEMS investigations of Al-implanted iron

-Fe surfaces were implanted with a nominal dose of 5×10¹⁷ Al ions/cm² at 50 keV and a current density of about 3.7 A/cm². Samples of different shapes and thicknesses have been used in order to test the influence of heat flow from specimen to target holder during implantation. Integral and energy differential (depth-selective)⁵⁷Fe conversion electron Mössbauer spectroscopy (CEMS and DCEMS) were employed. The spectra indicated a magnetic phase characterised by a broad hyperfine field distributionP(B _hf), a non-magnetic phase, and -Fe. The relative intensity of the non-magnetic phase was enhanced if the thermal contact during implantation became worse. An energy dependence of DCEM spectra in the L-electron range was observed. Model calculations using L-electron weight functions and experimental concentration profiles obtained by secondary neutral mass spectroscopy (SNMS) yielded fair agreement between calculated and experimental phase signals. The results demonstrate that the non-magnetic Fe-Al alloy phase with high Al concentration is located closer to the surface than the magnetic alloy phase, which extends to much larger depth than expected.     

Synthesis and modification of terrylenediimides as high-performance fluorescent dyes

Two new synthetic approaches to terrylenediimides, highly photostable fluorescent dyes, are described. For the first time terrylenediimide has been synthesised in a straightforward procedure that makes large quantities available. The second route includes an efficient cross-coupling reaction followed by a cyclodehydrogenation. Monofunctionalisation of the imide structure allows terrylenediimides now to be coupled with a variety of compounds, for example, by Suzuki cross-coupling, which can lead to an array of terrylenediimides with new functional groups such as hydroxy, amino, or carboxy groups needed to link up with other molecules. The functionalisation in the bay region is used to tune the properties of terrylenediimides and extend the range of applications, for example, by introducing water solubility. These tetrasubstituted terrylenediimides offer, depending on the substituents used, exciting features such as good solubility in common organic solvents, water solubility, or NIR absorption.     

Participation of Bao2* in chemiluminescence from low-pressure Ba(g) + O2 flames

New spectioscopic and vibronic population data support the essential correctness of BaO₂^* as the nascent polyatomic emitter and as the precursor to BaO (A ¹Σ⁺ → X¹Σ⁺) and (A' ¹Π → X¹Σ⁺) visible chemiluminescence from metal-rich Ba(g) + O₂ (+ Ar) diffusion flames at 2–350 mTorr- Absolute visible photon yields are reported over this pressure regime.     

Developments in synthesis,characterization, and self-assembly of polycarbodiimide systems

Described herein is a comprehensive survey on the most recent advancements in polycarbodiimide synthetic methodologies, structure determination, property design, and self-assembly. In particular, the ¹⁵N-isotopic enrichment of polycarbodiimides is detailed along with the use of ¹⁵N NMR to identify the regioregularity and mechanism of chiroptical switching in polycarbodiimides. Furthermore, the new Ni(II) mediated “living” polymerization is explained along with its utilization in the incorporation of polycarbodiimides into block copolymers, graft copolymers, and star polymers. Finally, we review the recent discoveries focusing on the highly tunable self-assembly behaviors of polycarbodiimide homopolymers and copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2915–2934