Association of polybutadiene living anions in cyclohexane

Simultaneous measurements of static and dynamic light scattering were made for cyclohexane solutions of living polybutadiene (PB) anion to characterize PB components existing in the solutions. There were two relaxation modes in the relaxation time spectra obtained by dynamic light scattering. The static structure factor and hydrodynamic radius of the major fast relaxation component obtained are explained by the unimer‐tetramer equilibrium model. The same model is also consistent with the data of the propagation reaction rate of the PB living anion in cyclohexane. The slow relaxation component is only minor (less than 1 wt %), but has a large radius of gyration of ca. 200 nm, and is assigned to aggregates consisting of a huge number of PB living anion chains. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1401–1407, 2005     

Rapid analysis of polychlorinated biphenyls in the gas phase with resonance-enhanced two-photon ionization: optimal injection of ions into the ion-trap storage/time-of-flight mass spectrometer.

LI-IT-TOFMS (laser ionization/ion-trap storage/time-of-flight mass spectrometry) is expected to be a powerful tool for environmental monitoring. In the research reported here, real-time LI-IT-TOFMS measurements were carried out on gaseous 2-4 chlorinated PCBs in order to evaluate the applicability of an environmental monitoring method. With respect to ion-trap storage for PCBs, we found that the effect was due to the driving RF voltage on the ring electrode in the ion trap. For PCBs ions produced by laser irradiation, we observed that it was more efficient to reach the center of the ion trap by using a gated RF voltage rather than by using a continuous RF voltage. The ion trajectories in the ion trap were simulated by SIMION 7.0. We found that the voltage of the exit end cap electrode affected both the number of ions trapped and the orbit of ions inside the trap cell. Optimization of this parameter was performed using both simulated and experimental results. The achievable PCBs sensitivity for real-time (1 min) measurement using the LI-IT-TOFMS method was found to be in the pptV range (<0.01 mg/m3N) by means of a comparison with the conventional gas sampling/GS-MS method. A satisfactory proportional relationship was confirmed between the laser-based and conventional results.     

Iron Halide Species Produced by Laser-Evaporation

Iron halide species were produced by the reaction of laser-evaporated iron atoms with halogen-containing reactant gas, and isolated in low-temperature matrices to obtain their Mössbauer spectra. Iron fluoride (Fe₂F₆, FeF₃ and Fe₂F₄) and iron iodide (FeI₂ and Fe₂I₄) were produced by the reaction of laser-evaporated iron atoms with sulfur hexafluoride SF₆ and methyl iodide CH₃I, respectively. The yields of the products varied depending on the concentration of reactant gas in the Ar matrix. Molecular orbital calculations were performed in order to confirm their assignments.     

The de Haas-van Alphen effect of graphite intercalation compounds with SbCl5 and HNO3

The de Haas-van Alphen (dHvA) effect of SbCl₅-graphite intercalation compounds of stage 2, 3 and 4, and residual HNO₃-compound of stage 3 has been studied. The dHvA spectra are stage dependent, and no combination frequency relations are found, which are in disagreement with Batallan et al.'s report. The amount of charge transfer per intercalant estimated on the basis of the rigid band model is 0.44, 0.49 and 0.43 for stage 4, 3 and 2 SbCl₅-compounds and is 0.14 for stage 3 HNO₃-compound.     

A pH Scale for the Protic Ionic Liquid Ethylammonium Nitrate

To quantify the properties of protic ionic liquids (PILs) as acid–base reaction media, potentiometric titrations were carried out in a neat PIL, ethylammonium nitrate (EAN). A linear relationship was found between the 14 pK_a values of 12 compounds in EAN and in water. In other words, the pK_a value in EAN was found to be roughly one unit greater than that in water regardless of the charge and hydrophobicity of the compounds. It is possible that this could be explained by the stronger acidity of HNO₃ in EAN than that of H₃O⁺ in water and not by the difference in the solvation state of the ions. The pH value in EAN ranges from ?1 to 9 on the pH scale based on the pH value in water.     

Iron films deposited on porous alumina substrates

Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 – 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.