NMRON studies of ferromagnetic hcp and fcc Co

The high resolution hyperfine spectroscopy, modulated adiabatic passage of oriented nuclei (MAPON), has been applied for the first time to high purity, elemental systems. Detailed comparisons between the electric quadrupole hyperfine interactions (EQI’s) and, in particular, their distributions, are obtained for⁶⁰CoCo where the hosts are a single crystal of hcp cobalt and a polycrystalline cobalt foil of predominantly fcc character. For hcp Co, with the electronic magnetization, M, parallel to the c-axis, the mode value P/h=3e²qQ/4I(2I−1)h=−48.5(5) kHz. This fractional distribution implies the sharpest electric field gradient (efg) measured in a metal to date, using MAPON spectroscopy, in excess of two times sharper than that of the most dilute impurity efg in a crystallographically cubic ferromagnetic host. The mode efg is V_zz=−27.3(32)×10¹⁹ Vm⁻². For the polycrystalline, predominantly fcc foil, prepared by quenching, the EQI mode value is P/h=−6.2(4) kHz with a FWHM of 12.0(7) kHz yielding a mode efg of V_zz=−3.5(5)×10¹⁹ Vm⁻².     

Synthesis of a novel methacrylic monomer iniferter and its application in surface photografting on crosslinked polymer substrates

(Methacryloyl ethylenedioxycarbonyl) benzyl N,N‐diethyldithiocarbamate (HEMA‐E‐In) was synthesized and used as a monomer iniferter to develop a novel, photopatternable grafting technology. This molecule functions as both a methacrylic monomer and a photoiniferter (photoinitiator–transfer agent–terminator). The structure of HEMA‐E‐In was characterized by ¹H NMR, Fourier transform infrared, and ultraviolet–visible spectroscopies. In the presence of the monomer iniferter, methyl methacrylate was polymerized by exposure to 365‐nm ultraviolet radiation, confirming the initiation capability of HEMA‐E‐In. After the copolymerization of HEMA‐E‐In into a methacrylate‐based polymer, attenuated total reflectance Fourier transform infrared spectra revealed that the photoiniferter functionality was present at the surface of this polymeric substrate. Photografting of poly(ethylene glycol) monomethacrylate monomer from the surface caused a significant change in the hydrophobicity of the surface as demonstrated by contact angle measurements. The novel monomer photoiniferter HEMA‐E‐In initiates the polymerization of bulk monomer and provides a reactive functionality that facilitates further initiation and polymer modification by the polymerization of different monomers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1885–1891, 2002     

Titanium production in a plasma reactor: A feasibility investigation

The feasibility of producing titanium metal from titanium tetrachloride in a thermal plasma under equilibrium and adiabatic expansion conditions has been theoretically investigated. Free energy minimization and adiabatic expansion calculations to simulate a nozzle expansion were used to study the practicality of production. The crucial requirements for the production of titanium powder from TiCl₄ and H₂ appear to be rapid quenching of the plasma gas at high temperature (e.g., 3700 K) and appropriate reactant concentrations. Quenching of tire plasma gas and production of titanium powder can be achieved by adiabatic expansion through a nozzle. Preliminary experimental data indicate that titanium powder of approximately 5 nm in size can be produced in an argon plasma rising a nozzle expansion approach.     

Pulsed NMRON oscillatory free induction decay signals in the angular distribution of gamma radiation from plated60CoFe

Results for an inhomogeneously broadened⁶⁰CoFe NMRON sample have been obtained for gamma detected single pulse (nutation) and two pulse (free induction decay) experiments in the region of intermediate-to-lowR(=₁/). Here ₁ is the angular frequency measure of the strength of the ferromagnetically enhanced RF field at the nucleus and is the HWHM of the inhomogeneously broadened line. Comparisons of the oscillatory FID signals obtained are made with the theoretical predictions of the following paper [6].     

Rapid method to determine 89/90Sr in steel samples

The sorption and diffusion behavior of cesium was studied to support the interpretation of the ongoing in-situ experiments in the Olkiluoto test site. The distribution coefficients of cesium in the Olkiluoto pegmatitic granite, veined gneiss and their main minerals were obtained by batch sorption experiments and the diffusion of cesium was studied in rock cubes. The results were modelled with PHREEQC and Comsol Multiphysics. The distribution coefficients of cesium were largest in biotite and veined gneiss. The effective diffusion coefficients of cesium from the diffusion model were 3 × 10⁻¹³ m² s⁻¹ for veined gneiss and 4 × 10⁻¹³ m² s⁻¹ for pegmatitic granite.