Experimental system for X-ray magnetic diffraction under extreme conditions

An experimental system for X-ray magnetic diffraction (XMD) under extreme conditions was constructed on the beamline BL39XU at SPring-8. This system aims at studying magnetic properties of ferromagnets through the measurements of magnetic form factors under the conditions of low temperature (5 K), high magnetic field (6 T) and high pressure (10 GPa). This system consists of a superconducting magnet (SCM), a diamond anvil cell (DAC), a two-axis manipulator for the DAC, a five-axis goniometer for the SCM, and an X-ray polarizer with a phase plate. Details of this system are presented. Experimental results on uranium telluride are shown as a performance test with this instrumentation.     

μSR studies of low charge carrier density heavy‐fermion systems

We report on μSR studies in low charge carrier density heavy‐fermion systems with cubic symmetry. Whereas for Ce₃Au₃Sb_4 and for Sm₃Te₄ the μSR data point to the presence of some kind of spin‐glass‐like magnetic states at low temperature, for Yb₄As₃ preliminary μSR studies just show a slight increase of the depolarization rate which indicates a slight slowing down of the Yb‐moment fluctuations. Consequently for this latter system, the large linear term of the specific heat seems indeed to be connected to electronic excitations. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solvation effects on photochemically-induced electron transfer from tris(bipyridyl)ruthenium to methylviologen

Summary The effects of mixed solvent systems and anions on the rate of reaction of the title compounds were investigated. The results were shown to be best interpreted in terms of ion-pair formation and solvation-desolvation effects, in addition to the factors included in the outer-sphere electron transfer rate theory expounded by Marcus.     

Are heavy-fermion metals Fermi liquids?

We present the results of specific-heat and resistivity measurements as a function of temperature, magnetic field and hydrostatic pressure on the Kondo lattice CeNi₂Ge₂, the heavy-fermion superconductors CeCu₂Si₂ and UBe₁₃ as well as the low-carrier-density system Yb₄As₃. “Non-Fermi-liquid” effects in the low-temperature normalstate properties of the three former systems are consistent with the existence of a “nearby” quantum critical point, presumably of antiferromagnetic type. Yb₄As₃, though showing the outward appearance of a Landau-type heavy-fermion metal, behaves very differently, i.e. as an extreme two-fluid system.     

Generation of 2-Carboethoxyethylzinc iodide and 3-carboethoxypropylzinc iodide and their application to the synthesis of γ- and δ-keto esters

2-Carboethoxyethylzinc iodide and 3-carboethoxypropylzinc iodide are generated by the reaction of the corresponding iodoesters with Zn-Cu couple and utilized for the palladium catalyzed coupling reaction with acid chloride to quantitatively provide gamma- and delta- keto esters, respectively.     

Nature of the magnetic excitation spectrum in (Sm,Y)S: CEF effects or an exciton?

The dynamic magnetic susceptibility spectrum in a single-crystal sample of the intermediate-valence compound Sm_0.67Y_0.33S is studied by inelastic neutron scattering with neutron momentum transfer and sample temperatures varying over wide ranges. Two coupled collective modes have been found in the spectrum. Unlike the higher energy mode, whose intensity approximately follows the form factor of Sm²⁺, the lower energy mode exhibits a stronger angular dependence than could be expected from the form factor for the localized f electrons. The total intensity of the inelastic component of the magnetic response decreases with increasing temperature; this is accompanied by the appearance of a broad quasi-elastic signal of a magnetic nature at significantly lower temperatures than follows from the calculated intensities of the transitions within the excited multiplet of the Sm²⁺ ion. An analysis of the observed features allows the suggestion to be made that the fine structure of the magnetic excitation spectrum in (Sm,Y)S is associated with the formation of an exciton-like intermediate-valence state on Sm ions rather than with the crystal-electric-field effects.     

Thermal and photochemical solvolysis of (E)- and (Z)-2-phenyl-1-propenyl(phenyl)iodonium tetrafluoroborate: benzenium and primary vinylic cation intermediates

The thermal and photochemical solvolysis of the two stereoisomeric 2-phenyl-1-propenyl(phenyl)iodonium tetrafluoroborates has been investigated in alcoholic solvents of varying nucleophilicity. The product profiles and rates of product formation in the thermal reaction are all compatible with a mechanism involving cleavage of the vinylic C-I bond assisted by the group in the trans position (methyl or phenyl), always leading to rearranged products. Depending on the nucleophilicity of the solvent, the primarily formed cations may or may not further rearrange to more stable isomers. The less reactive Z compound also yields some unrearranged vinyl ether product in the more nucleophilic solvents via an in-plane S(N)2 mechanism. The mechanism of the photolysis involves direct, unassisted cleavage of the vinylic, and aromatic, C-I bond in an S(N)1 mechanism. This produces a primary vinyl cation, which is partially trapped prior to rearrangement in methanol. The unrearranged vinyl ethers are mainly formed with retention of configuration via a lambda3-iodonium/solvent complex in an S(N)i mechanism. Thermal and photochemical solvolyses of iodonium salts are complementary techniques for the generation of different cation intermediates from the same substrate.     

Synthesis and properties of novel polysulfone bearing exomethylene structure

A novel polysulfone bearing exomethylene structure in the main chain was obtained by oxidation of polysulfide prepared by radical ring-opening polymerization of an eight-membered cyclic allyl sulfide, although the corresponding sulfone monomer was not polymerized at all. The thermal behaviors and the crystalline characters of the polysulfone and polysulfide are compared.